House dust mite reduction and avoidance measures for treating eczema

  • Review
  • Intervention

Authors


Abstract

Background

Eczema is an inflammatory skin disease that tends to involve skin creases, such as the folds of the elbows or knees; it is an intensely itchy skin condition, which can relapse and remit over time. As many as a third of people with eczema who have a positive test for allergy to house dust mite have reported worsening of eczema or respiratory symptoms when exposed to dust.

Objectives

To assess the effects of all house dust mite reduction and avoidance measures for the treatment of eczema.

Search methods

We searched the following databases up to 14 August 2014: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2014, Issue 8), MEDLINE (from 1946), Embase (from 1974), LILACS (from 1982), and the GREAT database. We also searched five trials registers and checked the reference lists of included and excluded studies for further references to relevant studies. We handsearched abstracts from international eczema and allergy meetings.

Selection criteria

Randomised controlled trials (RCTs) of any of the house dust mite reduction and avoidance measures for the treatment of eczema, which included participants of any age diagnosed by a clinician with eczema as defined by the World Allergy Organization. We included all non-pharmacological and pharmacological interventions that sought to reduce or avoid exposure to house dust mite and their allergenic faeces. The comparators were any active treatment, no treatment, placebo, or standard care only.

Data collection and analysis

Two authors independently checked the titles and abstracts identified, and there were no disagreements. We contacted authors of included studies for additional information. We assessed the risk of bias using Cochrane methodology.

Main results

We included seven studies of 324 adults and children with eczema. Overall, the included studies had a high risk of bias. Four of the seven trials tested interventions with multiple components, and three tested a single intervention. Two of the seven trials included only children, four included children and adults, and one included only adults. Interventions to reduce or avoid exposure to house dust mite included covers for mattresses and bedding, increased or high-quality vacuuming of carpets and mattresses, and sprays that kill house dust mites.

Four studies assessed our first primary outcome of 'Clinician-assessed eczema severity using a named scale'. Of these, one study (n = 20) did not show any significant short-term benefit from allergen impermeable polyurethane mattress encasings and acaricide spray versus allergen permeable cotton mattress encasings and placebo acaricide spray. One study (n = 60) found a modest statistically significant benefit in the Six Area, Six Sign Atopic Dermatitis (SASSAD) scale over six months (mean difference of 4.2 (95% confidence interval 1.7 to 6.7), P = 0.008) in favour of a mite impermeable bedding system combined with benzyltannate spray and high-filtration vacuuming versus mite permeable cotton encasings, water with a trace of alcohol spray, and a low-filtration vacuum cleaner. The third study (n = 41) did not compare the change in severity of eczema between the two treatment groups. The fourth study (n = 86) reported no evidence of a difference between the treatment groups.

With regard to the secondary outcomes 'Participant- or caregiver-assessed global eczema severity score' and the 'Amount and frequency of topical treatment required', one study (n = 20) assessed these outcomes with similar results being reported for these outcomes in both groups. Four studies (n = 159) assessed 'Sensitivity to house dust mite allergen using a marker'; there was no clear evidence of a difference in sensitivity levels reported between treatments in any of the four trials.

None of the seven included studies assessed our second primary outcome 'Participant- or caregiver-assessed eczema-related quality of life using a named instrument' or the secondary outcome of 'Adverse effects'.

We were unable to combine any of our results because of variability in the interventions and paucity of data.

Authors' conclusions

We were unable to determine clear implications to inform clinical practice from the very low-quality evidence currently available. The modest treatment responses reported were in people with atopic eczema, specifically with sensitivity to one or more aeroallergens. Thus, their use in the eczema population as a whole is unknown. High-quality long-term trials of single, easy-to-administer house dust mite reduction or avoidance measures are worth pursuing.

Résumé scientifique

Mesures de réduction et d'éviction des acariens dans le traitement de l'eczéma

Contexte

L'eczéma est une maladie inflammatoire de la peau qui a tendance à impliquer les plis de la peau, comme les plis des coudes ou des genoux ; c'est une affection intensément prurigineuse, avec de possibles rechutes et rémissions au fil du temps. Jusqu'à un tiers des personnes atteintes d'eczéma avec un test positif pour l'allergie aux acariens ont signalé l'aggravation de l'eczéma ou des symptômes respiratoires lorsqu'elles sont exposées à la poussière.

Objectifs

Évaluer les effets de toute mesure de réduction et d'éviction des acariens dans le traitement de l'eczéma.

Stratégie de recherche documentaire

Nous avons cherché dans les bases de données suivantes jusqu'au 14 août 2014 : le registre spécialisé du groupe Cochrane sur les affections dermatologiques, CENTRAL dans la Bibliothèque Cochrane (2014, Numéro 8), MEDLINE (depuis 1946), Embase (depuis 1974), LILACS (depuis 1982), et la base de données GREAT. Nous avons également fait des recherches dans cinq registres d'essais et vérifié des listes bibliographiques d'études incluses et exclues pour d'autres références à des études pertinentes. Nous avons fait des recherches manuelles dans les résumés de congrès internationaux sur l'eczéma et les allergies.

Critères de sélection

Les essais comparatifs randomisés (ECR) de toute mesure de réduction ou d'éviction des acariens pour le traitement de l'eczéma incluant des participants de tout âge avec un diagnostic d'eczéma posé par un clinicien selon la définition de la World Allergy Organization. Nous avons inclus toutes les interventions pharmacologiques et non pharmacologiques qui cherchaient à réduire ou à éviter l'exposition aux acariens et à leurs particules fécales allergisantes. La comparaison se faisait avec un traitement actif, l'absence de traitement, un placebo, ou le traitement standard seul.

Recueil et analyse des données

Deux auteurs ont indépendamment vérifié les titres et les résumés identifiés, il n'y a pas eu de désaccord. Nous avons contacté des auteurs des études incluses pour des renseignements supplémentaires. Nous avons évalué le risque de biais avec la méthodologie Cochrane.

Résultats principaux

Nous avons inclus sept études comportant 324 adultes et enfants atteints d'eczéma. Globalement, les études incluses avaient un risque élevé de biais. Quatre des sept études ont testé des intervention à multiples composants et trois une intervention unique. Deux des sept études ont inclus seulement des enfants, quatre des enfants et des adultes et une seulement des adultes. Les interventions pour réduire ou éviter l'exposition aux acariens incluaient les housses de matelas et de literie, le passage d'aspirateur plus fréquent ou de grande qualité sur les tapis et matelas et de sprays tuant les acariens.

Quatre études ont évalué notre critère de jugement principal « sévérité d'un eczéma évaluée par un clinicien suivant une échelle identifiée ». Parmi ces études, l'une (n=20) ne montrait aucun bénéfice significatif à court terme des housses de matelas en polyuréthane imperméables aux allergènes et d'un spray acaricide par comparaison à des housses de matelas en coton perméables aux allergènes et un spray acaricide placebo. Une étude (n=60) a trouvé un bénéfice modeste statistiquement significatif du score SASSAD (Six Area, Six Sign Atopic Dermatitis) sur six mois (différence moyenne de 4,2 (intervalle de confiance à 95 % 1,7 à 6,7), p=0,008 en faveur d'un système de literie imperméable aux acariens associé à un spray au tannate de benzyle et à un passage d'aspirateur muni d'un filtre de haute efficacité de filtration, par comparaison à des housses en coton perméables aux acariens, d'un spray d'eau avec des traces d'alcool et d'un aspirateur muni d'un filtre de basse efficacité de filtration. La troisième étude (n=41) n'a pas comparé la modification de la sévérité de l'eczéma entre les deux groupes de traitement. La quatrième étude (n=86) n'a rapporté aucune preuve d'une différence entre les groupes de traitement.

En ce qui concerne les critères de jugement secondaires « score d'évaluation de la sévérité globale de l'eczéma par le participant ou le soignant » et « quantité et fréquence du traitement topique requis », une étude (n=20) a évalué ces critères et a consigné des résultats similaires pour ces critères dans les deux groupes. Quatre études (n=159) ont évalué la « sensibilité à l'allergène d'acarien en utilisant un marqueur » ; dans aucun des quatre essais, il n'était rapporté de preuves claires d'une différence des niveaux de sensibilité entre les traitements.

Aucun des sept essais inclus n'a évalué notre critère de jugement secondaire « qualité de vie liée à l'eczéma évaluée par le participant ou le soignant à l'aide d'un instrument de mesure identifié » ou le critère de jugement secondaire « effets indésirables ».

Nous n'avons pu combiner aucun de nos résultats à cause de la diversité des interventions et de la pauvreté des données.

Conclusions des auteurs

Nous n'avons pas pu déterminer des implications claires pour aviser la pratique clinique à partir des données de très faible qualité actuellement disponibles. Les réponses modestes au traitement rapportées étaient retrouvées chez des personnes affectées d'un eczéma atopique, spécifiquement avec une sensibilité à un ou plusieurs allergènes aériens. Aussi, l'utilisation de ces traitements dans la population générale des personnes atteintes d'eczéma est inconnue. Des essais de long terme et de qualité élevée portant sur des mesures isolées et faciles à administrer de réduction ou d'éviction des acariens valent la peine d'être menés.

Notes de traduction

Traduction réalisée par le Centre Cochrane Français

Plain language summary

House dust mite reduction and avoidance measures for treating eczema

Background

Eczema is an intensely itchy skin disease that tends to involve skin creases, such as the folds of the elbows or knees. It is a worldwide problem affecting 5% to 20% of children. Around 2% of adults have the condition, and many have a more chronic and severe form. As many as a third of people with eczema who have a positive test for allergy to house dust mite have reported worsening of eczema or respiratory symptoms when exposed to dust. Ways to reduce or avoid exposure to house dust mite, such as covers for mattresses and bedding, increased or high-quality vacuuming of carpets and mattresses, or sprays that kill the mites, could lessen the severity of eczema for those who are sensitive to house dust mite. In this review, we aimed to assess the effects of all house dust mite reduction and avoidance measures for the treatment of eczema.

Review question

Do house dust reduction and avoidance measures provide a successful way to treat eczema?

Study characteristics

We found seven randomised controlled trials, which included 324 adults and children with eczema. We conducted the search up to 14 August 2014. Two of the seven trials included only children; four included children and adults; and one only included adults. Four of the seven trials compared treatments made up of multiple different house dust mite reduction and avoidance measures, and three trials tested a single treatment. The treatments were compared against other house dust mite reduction or avoidance treatments, no treatment, a placebo intervention (e.g., cotton bed covers), or standard care only.

Key results

We did not find any evidence to inform clinical practice. Some small treatment responses reported were in people with atopic eczema who were sensitive to one or more airborne allergens. We found no evidence of benefit in the other six included studies. Therefore, their use in the eczema population as a whole is unknown. High-quality longer trials of single, easy-to-use house dust mite reduction or avoidance measures should be performed.

Quality of the evidence

These seven very low-quality (Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach) small trials do not provide enough evidence to recommend any of the house dust mite reduction and avoidance measures tested.

Résumé simplifié

Mesures de réduction et d'éviction des acariens dans le traitement de l'eczéma

Contexte

L'eczéma est une maladie de la peau qui provoque d'intenses démangeaisons et qui a tendance à impliquer les plis de la peau, comme les plis des coudes ou des genoux. C'est un problème mondial affectant 5 % à 20 % des enfants. Environ 2 % des adultes en sont atteints et beaucoup ont une forme plus chronique et sévère. Jusqu'à un tiers des personnes atteintes d'eczéma qui ont un test positif pour l'allergie aux acariens ont signalé l'aggravation de l'eczéma ou des symptômes respiratoires lorsqu'elles étaient exposées à la poussière. Des moyens de réduire ou d'éviter l'exposition aux acariens, tels que des housses pour matelas et literie, un passage de l'aspirateur plus fréquent ou de haute qualité sur les tapis et matelas, ou des sprays qui tuent les acariens, pourraient diminuer la sévérité de l'eczéma pour ceux qui sont sensibles aux acariens. Dans cette revue, nous avons cherché à évaluer les effets de toutes les mesures de réduction et d'éviction des acariens pour le traitement de l'eczéma.

Objectif de la revue

Est-ce que des mesures de réduction et d'éviction des poussières de maison fournissent un moyen efficace pour traiter l'eczéma ?

Caractéristiques des études

Nous avons trouvé sept essais contrôlés randomisés, comprenant 324 adultes et enfants atteints d'eczéma. Nous avons effectué la recherche jusqu'au 14 août 2014. Deux des sept essais ont inclus seulement des enfants ; quatre des enfants et des adultes ; et un que des adultes. Quatre des sept essais ont comparé des traitements constitués de plusieurs mesures différentes de réduction et d'éviction des acariens, et trois essais ont testé un traitement unique. Les traitements ont été comparés à d'autres traitements de réduction ou d'éviction des acariens, ou à aucun traitement, ou à une intervention placebo (par exemple, couvre-lits en coton), ou à des soins standards.

Principaux résultats

Nous n'avons trouvé aucune preuve pour éclairer la pratique clinique. Certaines petites réponses au traitement rapportées l'ont été chez des personnes souffrant d'un eczéma atopique qui étaient sensibles à un ou plusieurs allergènes dans l'air. Nous n'avons trouvé aucune preuve d'un bénéfice dans les six autres études incluses. Par conséquent, leur utilisation dans la population atteinte d'eczéma, dans son ensemble, est inconnue. Des essais de haute qualité et de plus longue durée concernant des mesures faciles à utiliser de réduction ou d'éviction des acariens devraient être effectués.

Qualité des preuves

Ces sept petits essais de très faible qualité (approche GRADE - Grading of Recommendations Assessment, Development and Evaluation) ne fournissent pas suffisamment de preuves pour recommander l'une des mesures testées de réduction ou d'éviction des acariens.

Notes de traduction

Traduction réalisée par le Centre Cochrane Français

Laički sažetak

Mjere za smanjenje i izbjegavanja grinja iz kućne prašine u liječenju ekcema

Dosadašnje spoznaje

Ekcem je bolest intenzivnog svrbeža kože koja često uključuje kožne nabore, poput nabora na laktovima ili koljenima. Radi se o zdravstvenom problemu koji se javlja širom svijeta i pogađa od 5% do 20% djece. Oko 2% odraslih ima ekcem s time da se u njih većinom radi o kroničnom i teškom obliku. Trećina ljudi s ekcemom koji imaju pozitivan test na alergiju za grinje iz kućne prašine opisuje pogoršanje ekcema ili respiratornih simptoma kada su izloženi prašini. Postupci za smanjenje ili izbjegavanje izlaganja grinjama iz kućne prašine, kao što su navlake za madrace i posteljinu, povećano ili visoko-kvalitetno usisavanje tepiha i madraca, ili sprejevi koji ubijaju grinje, može smanjiti intenzitet ekcema kod osoba koje su osjetljive na grinje iz kućne prašine. U ovom Cochrane sustavnom pregledu cilj je bio procijeniti učinke svih načina smanjenja i mjera izbjegavanja grinja iz kućne prašine na liječenje ekcema.

Istraživačko pitanje

Da li postupci za smanjenje i izbjegavanje grinja iz kućne prašine omogućuju uspješan način liječenja ekcema?

Obilježja istraživanja

Nađeno je 7 randomiziranih kliničkih studija koje su obuhvatile 324 osobe odrasle i dječje dobi s ekcemom. Literatura je pretražena zaključno s datumom 14. kolovoza 2014. Dvije od sedam studija je uključivalo samo djecu; četiri su uključivala djecu i odrasle; i samo je jedno uključivalo isključivo odrasle osobe. Četiri od sedam studija uspoređivale su tretmane koji su uključivali različite načine smanjenja i izbjegavanja grinja iz kućne prašine, a ostale tri studije su se ograničile na samo jedan način liječenja. Predloženi načini liječenja su se uspoređivali s ostalim načinima smanjenja i izbjegavanja kućnih grinja, nikakvim liječenjem, placebo intervencijom (npr. pamučni pokrivači za krevet) ili samo standardnom skrbi.

Ključni rezultati

Nisu nađeni nikakvi dokazi koji bi omogućili donošenje zaključaka za kliničku praksu. Mali broj ljudi s atopijskim ekcemom koji su bili osjetljivi na jednu ili više vrsti alergena u zraku odgovorio je na terapiju. Nisu nađeni nikakvi dokazi ili koristi u ostalih šest uključenih studija. Prema tome, njihova primjena u populaciji ljudi s ekcemom u cjelini je nepoznata. Potrebno je provesti duža visoko-kvalitetna istraživanja pojedinačnih, lako upotrebljivih mjera smanjenja ili izbjegavanja grinja iz kućne prašine.

Kvaliteta dokaza

Sedam navedenih malih studija niske kvalitete nisu pružile dovoljno dokaza kako bi se preporučila ijedna mjera smanjivanja i izbjegavanja grinja iz kućne prašine koja se testirala.

Bilješke prijevoda

Cochrane Hrvatska
Prevela: Ivana Novak
Ovaj sažetak preveden je u okviru volonterskog projekta prevođenja Cochrane sažetaka. Uključite se u projekt i pomozite nam u prevođenju brojnih preostalih Cochrane sažetaka koji su još uvijek dostupni samo na engleskom jeziku. Kontakt: cochrane_croatia@mefst.hr

Laienverständliche Zusammenfassung

Maßnahmen zur Verminderung und Vermeidung von Hausstaubmilben zur Ekzembehandlung

Hintergrund

Ekzem ist eine stark juckende Hauterkrankung, die vor allem an Hautfalten, wie Armbeugen oder Kniekehlen auftritt. Es handelt sich um ein weltweites Problem, das bei 5% bis 20% aller Kinder auftritt. Rund 2% der Erwachsenen leiden an der Krankheit, darunter viele an einer chronischen und schweren Form. Nicht weniger als ein Drittel der an Ekzem leidenden Menschen mit positivem Hausstauballergietest berichten über eine Verschlimmerung des Ekzems oder der Atemwegsbeschwerden, wenn sie Staub ausgesetzt sind. Verfahren zur Reduzierung oder Vermeidung der Exposition gegenüber Hausstaubmilben wie Bezüge für Matratzen und Bettzeug, vermehrte und qualitativ hochwertige Behandlung von Teppichen und Matratzen mit dem Staubsauger oder milbenabtötende Sprays könnten das Ekzem bei Menschen, die sensibel auf Hausstaubmilben reagieren lindern. Mit diesem Review sollte die Wirkung aller Maßnahmen zur Reduzierung und Vermeidung von Hausstaubmilben für die Ekzembehandlung bewertet werden.

Reviewfrage

Sind Maßnahmen zur Reduzierung und Vermeidung von Hausstaubmilben eine wirksame Art der Ekzembehandlung?

Studienmerkmale

Wir fanden sieben randomisierte kontrollierte Studien, die insgesamt 324 Erwachsene und Kinder mit Ekzem einschlossen. Unsere Suche ist auf dem Stand vom 14. August 2014. Zwei von den sieben Studien schlossen nur Kinder ein, vier schlossen Kinder und Erwachsene ein und nur eine Studie Erwachsene allein. In vier der sieben Studien wurden Behandlungen verglichen, die aus mehreren verschiedenen Maßnahmen zur Reduzierung und Vermeidung von Hausstaubmilben bestanden, und drei Studien testeten eine einzige Behandlung. Die Behandlungen wurden mit anderen Behandlungen zur Reduzierung und Vermeidung von Hausstaubmilben, einer Situation ohne Behandlung, einer Placebo-Intervention (z.B. baumwollene Bettlaken) und reiner Standard-Pflege verglichen.

Hauptergebnisse

Wir fanden keine Evidenz, die die klinische Praxis beeinflusst. Es wurde über kleine Behandlungserfolge bei Personen mit atopischem Ekzem berichtet, die auf ein oder mehrere luftgetragene Allergene reagieren. In den anderen sechs betrachteten Studien fanden wir keine Evidenz für einen Nutzen. Demnach ist ihr Nutzen bei der Gesamtpopulation mit Ekzem unbekannt. Es sollten hochwertige längere Studien zu einzelnen, leicht anzuwendenden Maßnahmen zur Reduzierung oder Vermeidung von Hausstaubmilben durchgeführt werden.

Qualität der Evidenz

Diese sieben kleinen Studien von sehr niedriger Qualität (GRADE-System zur Bewertung der Evidenz und Formulierung von Empfehlungen) liefern keine ausreichende Evidenz, um eine der getesteten Maßnahmen zur Reduzierung und Vermeidung von Hausstaubmilben empfehlen zu können.

Anmerkungen zur Übersetzung

Koordination durch Cochrane Schweiz.

Резюме на простом языке

Меры по снижению и предотвращению воздействия клещей домашней пыли при лечении экземы

Актуальность

Экзема это кожное заболевание с интенсивным зудом, с тенденцией поражения складок кожи, например сгибов локтей или коленей. Это всемирная проблема, затрагивающая от 5% до 20% детей. Около 2% взрослых страдают этим заболеванием, и многие из них имеют хроническую и тяжелую форму заболевания. Около трети людей с экземой, у которых был положительный тест на аллергию на клеща домашней пыли, сообщили об обострении экземы или респираторных симптомов при воздействии пыли. Различные способы, позволяющие уменьшить воздействие клещей домашней пыли или избежать его, такие как покрытия для матрасов и постельных принадлежностей, улучшенная или высококачественная чистка ковров и матрасов пылесосом, или убивающие клещей спреи, могут уменьшить тяжесть экземы у людей, чувствительных к клещам домашней пыли. В этом обзоре мы стремились оценить влияние всех мер по предотвращению и снижению воздействия клещей домашней пыли при лечении экземы.

Вопрос обзора

Являются ли меры по снижению и предотвращению воздействия домашней пыли успешным способом лечения экземы?

Характеристика исследований

Мы нашли семь рандомизированных контролируемых испытаний, которые включали 324 взрослых и детей с экземой. Мы провели поиск по 14 августа 2014 года. Два из семи клинических испытаний включали только детей; четыре клинических испытания включали детей и взрослых; и одно клиническое испытание включало только взрослых. В четырех из семи клинических испытаний сравнивали виды лечения с применением множества различных мер по снижению и предотвращению воздействия клещей домашней пыли, и в трех клинических испытаниях проверяли только один вид лечения. Виды лечения сравнивали с другими видами лечения с применением мер по уменьшению или предотвращению воздействия клещей домашней пыли, отсутствием лечения, плацебо (например, хлопковое постельное белье), или только со стандартным уходом.

Основные результаты

Мы не нашли каких-либо доказательств, чтобы информировать клиническую практику. Сообщали о некоторых небольших ответах на лечение у людей с атопической экземой, чувствительных к одному или более ингаляционных/воздушных аллергенов. Мы обнаружили отсутствие доказательств пользы в шести других включенных исследованиях. Поэтому место этих мер в применении у населения с экземой,в целом, неизвестно. Необходимо проведение более длительных клинических испытаний высокого качества с единичными, простыми в использовании мерами по уменьшению или предотвращению воздействия домашней пыли.

Качество доказательств

Эти семь небольших клинических испытаний очень низкого качества (по GRADE; Градация Рекомендаций, Анализ, Разработка и Оценка) не предоставляют достаточных доказательств, чтобы рекомендовать какой-либо из протестированных способов уменьшения и предотвращения воздействия клещей домашней пыли.

Заметки по переводу

Перевод: Раззакова Чинара Маратовна. Редактирование: Юдина Екатерина Викторовна. Координация проекта по переводу на русский язык: Казанский федеральный университет - аффилированный центр в Татарстане Северного Кокрейновского Центра. По вопросам, связанным с этим переводом, пожалуйста, обращайтесь к нам по адресу: lezign@gmail.com

Summary of findings(Explanation)

Summary of findings for the main comparison. 
  1. aReasons for a rating of very low quality: moderate proportions of participants not analysed (losses to follow up); not clear whether the severity of eczema outcome assessors were blinded or not; severity of eczema was not analysed between treatment groups; the total Leicester Sign Score (LSS) data not reported, including no analyses.
    bReasons for a rating of very low quality: big differential in the proportions of participants who were not included in the analyses, small numbers of participants, baseline severity scores are very different, with the active treatment group having a higher baseline severity and it is unclear whether this was adjusted for in the analyses.
    cReasons for a rating of very low quality: differences in baseline severity, with the active group being more severe, for which it is unclear whether this was adjusted for in the analyses; small numbers of participants in both trials.
    ¹Oosting 2002
    Active interventions: mite impermeable encasings for mattress, pillow, and duvet.
    Control interventions: mite permeable encasings for mattress, pillow, and duvet.
    Results: active treatment group (LSS disease activity 17 (6 to 60) to 13 (0 to 55), P = 0.017) (LSS extent 19.5 (3 to 88) to 14.5 (0 to 87), P = 0.038) (LSS itching score mm 73.5 (0 to 100) to 63 (4 to 100), P = 0.045), but did not report the total LSS scores. The trial report mentioned that there were no significant between-group differences, but did not report any more detail.
    ²Tan 1996
    Active interventions: mite impermeable encasings, acaricide spray on carpets, and high-filtration vacuum cleaner.
    Control interventions: mite permeable encasings, water with a trace of alcohol spray on carpets, and standard-filtration vacuum cleaner.
    Results: mean differences in the mean severity scores were -12.6 in the active treatment group and -4.2 in the control group. The analysis of the differences in the reduction in severity scores between groups used analysis of covariance with initial eczema scores and logs of the initial mattress dust weight and bedroom carpet Der p1 (Dermatophagoides pteronyssinus) concentration as covariates and reported a mean difference of 4.2 (95% confidence interval (Cl) 1.7 to 6.7), P = 0.008 (unpaired student's t-test) in favour of the GORE-TEX® bedding system, benzyltannate spray, and high-filtration vacuuming.
    ³Gutgesell 2001
    Active interventions: allergen impermeable encasings, acaricide spray (tannic acid and benzyl benzoate).
    Control interventions: allergen permeable encasings, water with a trace of ethanol spray.
    Results: no statistically significant difference in reduction of severity after one year (P = 0.901) (non-parametric tests for tests of repeated measures) between the treatment groups. The active encasings group had a reduction in SCORing Atopic Dermatitis (SCORAD) from a median (interquartile range) of 46 (37 to 55) to 40 (32 to 63), and the control encasings had a change from 35 (24 to 46) to 37 (30 to 45). This study did not provide many details; the SCORAD scores were abstracted from a graph.
    Ricci 2000
    Active interventions: mite impermeable encasings for mattresses and pillows, weekly hot wash of bedding, frequent vacuuming of living room and bedroom, soft toys and carpets regularly cleaned or removed, no pets allowed.
    Control interventions: no recommendations for changing cleaning patterns given (no treatment).
    Results: The reduction in severity was recorded within the group using the dust mite avoidance measures (a reduction from a mean of 33 to 26 SCORAD points) and the group who used normal cleaning patterns (a reduction from a mean of 27 to 24 SCORAD points); however, the change in severity of eczema was not compared between the two groups.

House dust mite reduction and avoidance measures for treating eczema

Patient or population: children and adults with eczema with proven sensitivity to house dust mite

Settings: participant's home

Intervention: active

Comparison: control

OutcomesNumber of Participants
(studies)
Quality of the evidence
(GRADE)
Comments
Clinician-assessed global eczema severity using a named scale (Leicester Sign Score)86 (1)⊕⊝⊝⊝ very low a Oosting 2002¹
Clinician-assessed global eczema severity using a named scale (SASSAD)60 (1)⊕⊝⊝⊝ very low b Tan 1996²
Clinician-assessed global eczema severity using a named scale (SCORAD)61 (2)⊕⊝⊝⊝ very low c Gutgesell 2001³; Ricci 2000
Participant- or caregiver-assessed eczema-related quality of life (named instrument)0 (0)N/A-
GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

Background

Description of the condition

Disease definition

Eczema is an inflammatory skin disease that tends to involve flexural skin creases, such as the folds of the elbows or knees. Eczema is an intensely itchy skin condition, which can relapse and remit over time (Williams 1994).

Eczema is also often called atopic dermatitis or atopic eczema. The nomenclature for allergy (Johansson 2001) has been revised and is now based on the mechanisms by which allergic reactions are initiated and mediated, although this nomenclature has not yet been universally adopted. The term atopic eczema can only be used when sensitisation to common allergens has been verified by identifying immunoglobulin E (IgE) antibodies in the blood or by a positive skin prick test (Johansson 2004). We have used the term eczema in this review throughout to refer to what is usually described as atopic dermatitis or atopic eczema. We have only used the terms atopic eczema and atopic dermatitis when IgE sensitisation has been confirmed. No clinical relevance for diagnosis between proven atopic eczema and non-atopic eczema has yet been found (Flohr 2004).

See Figure 1 for an example of this condition.

Figure 1.

Acute atopic eczema in a child. Copyright © 1991 Professor Hywel Williams: reproduced with permission

Epidemiology and causes

Eczema is a worldwide problem affecting 5% to 20% of children (Williams 1999). Many of the approximately 2% of adults with eczema have to cope with a more severe and longer lasting form of the condition (Charman 2000a). The prevalence of eczema varies considerably between and within countries (Williams 1999). Of the children with eczema in the UK under the age of five years old, around 2% have severe disease, and 84% have mild disease (Emerson 1998).

Eczema is a complex disease, which probably depends on a complex interaction between several genetic and environmental factors. Recently, a genetic defect that affects the production of a key protein for skin barrier function (filaggrin gene mutation) has been linked to an increased risk of atopic eczema (eczema with IgE sensitisation) (Muller 2009; van den Oord 2009). External factors, including house dust mites (Van Bever 2002), microbes (Bjorksten 2001), climate, stress, and air pollution (Brauer 2007; Penard -Mornard 2005), have all been associated with an altered risk of developing eczema (Langan 2006). People with severe eczema tend to be sensitive to multiple indoor and outdoor allergens.

Clinical features

Acute (short-term) eczema often presents as mainly redness, collections of fluid in the top layers of the skin in the form of 'water blisters' (vesicles), and oozing. Chronic (long-term) eczema has scaling, skin thickening, altered pigmentation, and exaggerated surface markings as the predominant signs. Mild eczema often presents as localised mild scaling, ranging through to severe eczema, which generally involves the whole body, with redness, oozing, and secondary infection (Birnie 2008). Eczema mainly affects the flexural creases of the elbows and knees and the face and neck, although any part of the body can be affected. The main symptom is itching, which will often lead to a vicious cycle of scratching, damage, and more itching: the so called "itch scratch itch" cycle (Bath-Hextall 2008; Boyle 2008).

Natural history

Eczema usually develops early in childhood, with 60% of cases being seen before the age of one year old and 85% of cases seen before the age of five years old (Emerson 2001). The majority (60% to 70%) of children who have eczema will be clear by 15 years old, although some later relapse. People with eczema are also more likely to have other atopic diseases, such as asthma, rhinitis, and food allergy (Beck 2000). The tendency for people who have or have had eczema to go on to develop asthma and allergies has become known as the 'atopic march'. Whether this 'march' from one allergic disease to another exists is the subject of much speculation (Curtiss 2007; Williams 2006).

Impact

Eczema varies in severity, often from one hour to the next (Bath-Hextall 2008; Boyle 2008). Chronic sleep disturbance due to itching and scratching can result in a poor quality of life (Meltzer 2008). The social and emotional impact on the family of a child with eczema can be in excess of the impact of type I diabetes (Su 1997). Bacterial and viral infections can often present as complications of eczema (McHenry 1995). A child with eczema can have their confidence affected by greasy ointments making the skin look unsightly and making them less likely to join in with sports or social events. Adults with eczema often have low self-esteem, and relationships can be hard to initiate and sustain. Everyday tasks become difficult when the skin of the hands becomes very dry, sore, and broken. (Bath-Hextall 2008; Boyle 2008). Severe eczema in childhood may lead to delayed development and puberty (Baum 2002).

Families of people with eczema (Kemp 2003) as well as a country's health service can incur substantial economic costs (Mancini 2008; Verboom 2002). Eczema has been shown to have similar healthcare costs to other diseases (Ellis 2002).

Families often pay a large proportion of the costs (some estimates put this at a third of the total costs for children under five), such as for special clothing; washing extra laundry; and (especially) house dust mite control measures, such as mattress protectors (Emerson 2001). Indirect costs for families are also important, such as through lost working days when parents are looking after a child with eczema. The costs to society include the health professional's costs; parents who cannot seek employment; and the child who, as a result of missing school, may face employment limitations (Su 1997).

Description of the intervention

The effectiveness of interventions that reduce or avoid exposure to house dust mites has been the subject of much uncertainty. A possible link between reduction of house dust mite exposure and improvement in asthma has been the subject of intensive research, but many of the trials have shown conflicting results, and there is debate about how the evidence should be interpreted (Gotzsche 2008; Platts-Mills 2008). The same effect has been proposed for eczema, as evidence has shown a link between mite sensitisation, exposure, and the severity of atopic dermatitis (Mitchell 1982; Platts-Mills 1983).

House dust mites

There are many different species of mite in house dust; however, only three of these are very common in homes throughout the world: Dermatophagoides farinae,Dermatophagoides pteronyssinus, andEuroglyphus maynei, which are found in temperate climates. In tropical climates, the mite Blomia tropicalis is often more common (Arlian 2001).

As well as the live mites, their dead bodies and faeces have also been shown to produce allergic reactions. House dust mites are dependant on the atmospheric humidity as they are 70% to 75% water by weight and maintain this by absorbing water from the air (Arlian 2001). Some of the interventions to reduce their numbers are therefore aimed at reducing the indoor humidity of dwellings.

See Figure 2 for a picture of a house dust mite.

Figure 2.

A house dust mite. Copyright © 2013 Professor Thomas Platts-Millls: reproduced with permission

Ways to reduce or avoid exposure

There are many different interventions used to attempt to reduce or avoid exposure to house dust mites, dead or alive, and their faeces. These can be divided into physical and chemical interventions. Physical interventions include physical barriers (e.g., mattress encasings), reducing indoor relative humidity (e.g., ventilation), changing floor covering, removing soft furnishings, vacuuming, air filters, ionisers, removal of fluffy or soft toys, heat exchangers, freezing, and washing (55 degrees Celsius or higher). Chemical interventions include acaricide sprays (Arlian 2001; Friedmann 1999) and antifungal agents that appear to reduce mite numbers because of the apparent symbiotic relationship between mites and fungi (Koren 1993).

Nearly all interventions to reduce or avoid exposure to house dust mite are used in the home. This effort is usually centred around the bedroom of the person affected, as a large percentage of house dust mite exposure is related to close contact with the bed and associated bedding. A regimen with many methods may be used, especially where the house dust mite levels are high or where the person affected experiences severe allergic reactions (Arlian 2001). The significance of any exposure to house dust mites outside the home is not well studied, but is an important consideration, especially as a large proportion of people with eczema will spend many hours each week in another environment, such as school or work.

How the intervention might work

As many as a third of people with eczema who have a positive test for allergy to house dust mite have reported worsening of eczema or respiratory symptoms when exposed to dust (Hallai 2009). The research into the relationship between house dust mite allergens and eczema has a long history. In 1949, Tuft showed that reducing the levels of house dust mite in the home could benefit people with eczema (Tuft 1949). The exact mechanism by which exposure to house dust mite results in worsening of eczema is unclear; however, when people with eczema are patch tested with house dust mite, CD4 positive T cells specific to house dust mite are found in the patch of skin that has developed eczematous characteristics (Friedmann 1999; van Reijsen 1992).

Why it is important to do this review

Eczema often follows a chronic, relapsing course (Williams 1994), and people with eczema frequently end up using many different topical and sometimes systemic treatments. Some of these treatments, such as topical corticosteroids, have potentially serious side-effects (e.g., skin thinning), which although they are rare with appropriate treatment, can lead to low levels of treatment compliance because of an inappropriate level of fear of using the treatment (Charman 2000b).

Many of the interventions that aim to reduce or avoid house dust mite exposure often have few or no known adverse effects. In particular, because of families spending a significant percentage of the total cost of managing eczema on house dust mite control measures (Emerson 2001), it is important that the evidence for these interventions is summarised to highlight any potential benefit or harm. This will enable people with eczema or their caregivers and policy-makers to make more informed decisions.

Objectives

To assess the effects of all house dust mite reduction and avoidance measures for the treatment of eczema.

Methods

Criteria for considering studies for this review

Types of studies

Randomised controlled trials (RCTs) that assess the efficacy of any of the house dust mite reduction and avoidance measures for the treatment of eczema. We included trials that allowed co-treatments. We excluded quasi-randomised trials. We would have included cross-over trials, only if the data at the end of the first period were available, because of the possibility of treatment carry-over effects, but we did not identify any for inclusion. We would have included cluster-randomised trials but identified none for inclusion.

We excluded trials on house dust mite reduction and avoidance measures for the prevention of eczema.

Types of participants

Anyone of any age diagnosed with eczema as defined by the World Allergy Organization, or atopic eczema, childhood eczema, or atopic dermatitis by a clinician. We would have included a diagnosis of Besnier's prurigo or neurodermatitis if there was evidence of eczema in the flexures before inclusion, but we identified none for inclusion. We excluded participants with skin comorbidities, such as psoriasis, ichthyosis vulgaris, or skin infections, including infected eczema. We accepted diagnosis using the Hanifin and Rajka criteria (Hanifin 1980) or the UK diagnostic criteria (Williams 1994).

Types of interventions

All non-pharmacological and pharmacological interventions that seek to reduce or avoid exposure to house dust mite and their faeces (which are also allergenic). The comparators were any active treatment, no treatment, placebo, or standard care only. They are broadly divided into the following categories.

Educational
  • Information on ways to reduce and avoid house dust mite

Environmental manipulation
  • Mattress encasings

  • Duvet and pillow encasings

  • Removal of soft floor covering (e.g., carpets, rugs)

  • Vacuuming (e.g., different number of times, higher filtration)

  • Ventilation systems

  • Removing people with eczema from their environment for a defined period (e.g., removing children from a school in a lower altitude to a school in a high altitude area)

  • Ultraviolet C (UVC) light sources

Pharmacological
  • Acaricide sprays

Types of outcome measures

Primary outcomes
  1. Clinician-assessed global eczema severity using a named scale (e.g., SCORing Atopic Dermatitis (SCORAD)) or modification of such a scale.

  2. Participant- or caregiver-assessed eczema-related quality of life using a named instrument.

Secondary outcomes
  1. Participant- or caregiver-assessed global eczema severity score.

  2. Amount and frequency of topical treatment required.

  3. Sensitivity to house dust mite allergen using a marker (e.g., specific IgE).

  4. Adverse effects.

Main outcomes for 'Summary of findings' table

We have provided data in the 'Summary of findings' table for the primary outcome Clinician-assessed global eczema severity using a named scale (e.g., SCORAD) or modification of such a scale. We decided that attempting to include only those severity measurements that were validated was too restrictive and that acceptable validation was difficult to quantify.

Timing of outcome assessment

Short-term outcomes were six months or less, and long-term outcomes were over six months. Long-term outcomes were of primary importance because of the need to assess whether the treatment effects were sustained over a useful length of time for people with eczema.

Adverse outcomes

We reported all adverse events from the included and excluded studies and the separate search for rare but potentially serious side-effects.

Economic data

We did not consider economic factors in this review.

Search methods for identification of studies

We aimed to identify all relevant RCTs regardless of language or publication status (published, unpublished, in press, or in progress).

Electronic searches

We searched the following databases up to 14 August 2014:

  • the Cochrane Skin Group Specialised Register using the following search terms: ((atopic and dermatitis) or (atopic and eczema*) or eczema* or neurodermatitis or (infant* and eczema*) or (child* and eczema*) or (besnier* and prurigo)) AND ((house and dust and mite*) or (dust and mite*) or (pyroglyphidae or dermatophagoide* or euroglyphus or blomia));

  • the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Issue 1), in The Cochrane Library using the search strategy in Appendix 1;

  • MEDLINE via Ovid (from 1946) using the strategy in Appendix 2;

  • Embase via Ovid (from 1974) using the strategy in Appendix 3; and

  • LILACS (Latin American & Caribbean Health Sciences Literature, from 1982) using the strategy in Appendix 4; and

  • The Global Resource of EczemA Trials (GREAT database). Centre of Evidence Based Dermatology. Accessed at www.greatdatabase.org.uk on 2 September 2014 using the search strategy 'house' OR 'dust' OR 'mite' across all fields.

Trials databases

We searched the following trials registers up to 2 September 2014 using the terms 'eczema' and 'house dust mite':

Searching other resources

References from published studies

We checked the bibliographies of included and excluded studies for further references to relevant RCTs.

Unpublished literature

We planned to obtain unpublished ongoing trials information via correspondence with trial authors.

Conference proceedings

We scanned for further RCTs the abstracts from the International Research Workshops on eczema and major dermatology and allergy conference proceedings not already recorded in the Cochrane Skin Group Specialised Register.

Adverse effects

We did not perform a separate search for adverse effects of the target interventions. We did examine data on adverse effects of all of the reduction and avoidance measures used for the treatment of eczema from the included studies.

Data collection and analysis

Selection of studies

Two authors (HN and EP) independently checked the titles and abstracts identified from the searches. We excluded studies where it was clear that they did not refer to a randomised controlled trial on house dust mite avoidance or reduction measures for the treatment of eczema. When it was unclear, then we obtained the full text of the study, which two authors (HN and EP) independently assessed. The authors decided which trials fitted the inclusion criteria. A third author (RB or HW) would have resolved any disagreement by discussion, but there were no disagreements. We recorded the reasons for exclusion in the 'Characteristics of excluded studies' tables.

Data extraction and management

Two authors (HN and EP) independently extracted data using a specially designed data extraction form and checked and entered the data into RevMan (Review Manager 2014). Data extracted included participant numbers, characteristics, interventions, outcomes, and results. The same two authors resolved discrepancies between them, with discussion with a third author (RB or HW) if necessary. We obtained missing data from trial authors where possible. We were not blinded to the names of trial authors, journals, or institutions.

Assessment of risk of bias in included studies

The quality assessment included an evaluation of the following components for each included study, since there is some evidence that these are associated with biased estimates of treatment effect (Higgins 2011):
(a) the method of generation of the randomisation sequence;
(b) the method of allocation concealment - we considered it 'adequate' if the assignment could not have been foreseen;
(c) who was blinded or not blinded (participants, clinicians, outcome assessors); and
(d) how many participants were lost to follow up in each arm (split into postrandomisation exclusions and later losses if possible) and whether participants were analysed in the groups to which they were originally randomised (intention-to-treat).

In addition, we assessed the following:
(e) degree of certainty that participants had eczema;
(f) baseline comparison for severity of disease;
(g) whether outcomes and any subgroup analyses were clearly defined; and
(h) treatment compliance - whether or not measurements were taken and, if so, whether they were high.

Measures of treatment effect

We were unable to combine any of our results because of variability in the interventions and paucity of data. If in future updates of this review it is possible to carry out quantitative analyses, we will do the following: For dichotomous outcomes, we will express the results as risk ratios (RR) and 95% confidence intervals (CI); we will not express these as odds ratios as the event rates are common and we do not wish to overestimate the treatment effect. We will express the continuous outcomes as mean differences (MD) and 95% CI. For dichotomous outcomes, we will express the results as number needed to treat (NNT) with 95% confidence intervals and the baseline risk to which it applies.

Unit of analysis issues

Cross-over trials

If we had identified cross-over trials, we would have conducted a paired analysis according to the guidance given in the Cochrane Handbook for Systematic reviews of Interventions, chapter 16 (Higgins 2011). We would have analysed these trials separately to the parallel group studies or studies of other designs.

Cluster trials

If we had identified cluster trials, we would have analysed these appropriately using the interclass correlation coefficient, and we would have synthesised these with the parallel group.

Within-person trials

If we had identified within-person trials, we would have abstracted the paired analysis results from the original paper and reported these. We would have analysed these separately from the parallel group and cross-over trials.

Multiple treatment group trials

One included trial, Colloff 1989, had more than one active intervention arm. If we had had sufficient numbers of studies to carry out a meta-analysis, we would have followed the advice in the Cochrane Handbook for Systematic Reviews of Interventions, chapter 16 (Higgins 2011), and considered, for example, whether any of the arms could be sensibly combined, or whether we should include only the arms which were compatible with other trials.

Dealing with missing data

We contacted study authors for clarification of missing data and summary statistics.

Assessment of heterogeneity

If we had assessed heterogeneity, we would have used the I² statistic. If substantial (I² statistic > 50%) heterogeneity had existed between trials for any of the outcomes, we would have explored the reasons for the heterogeneity, such as differences in participant factors or treatment factors. We described the findings narratively, as it was not possible to perform a meta-analysis.

Assessment of reporting biases

If we could have pooled together 10 or more studies, we would have performed funnel plots to assess possible reporting biases.

Data synthesis

If trials with similar types of intervention had been available, we would have used a fixed-effect model in the first instance and tested for heterogeneity. We would then have used a random-effects model for further analyses if we had found significant heterogeneity.

Subgroup analysis and investigation of heterogeneity

If the number of studies allowed, we would have explored the effect of potential confounding variables and effect modifiers of the meta-risk estimate using meta-regression methods, including, for example, severity of eczema, age, length of intervention, sensitivity to house dust mite allergens, and house dust mite allergen levels if the appropriate data had been available.

Sensitivity analysis

We had planned to explore reasons for heterogeneity between trials and, if necessary, perform sensitivity analyses examining the effects of excluding subgroups, such as very low- or low-quality (GRADE) trials.

Results

Description of studies

Results of the search

The searches of the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library, MEDLINE, Embase, LILACS, and GREAT databases retrieved 308 unique records. We identified one record through searching other sources, making 309 records in total. Of these 309 records, we excluded 290 after scrutinising the titles and abstracts. We obtained the full texts of the remaining 19 records. From these 19 records, we excluded eight references. The remaining 11 references referred to seven different studies, which we included (see Figure 3). We did not identify any studies that needed further information regarding classification or any ongoing studies.

Figure 3.

Study flow diagram

Included studies

In this review, we included seven studies of 324 adult and child participants with eczema. Eleven references reported these seven studies.

Design

Six out of the seven included studies divided the participants into two separate groups and performed what was either reported to be or appeared to be from the description a parallel group study (Endo 1997; Gutgesell 2001; Oosting 2002; Ricci 2000; Tan 1996; Terreehorst 2005). The remaining study (Colloff 1989) randomised the participants into four groups.

We did not identify any cross-over trials, cluster trials, or within-person trials.

Sample sizes

All seven included studies were small (Colloff 1989; Endo 1997; Gutgesell 2001; Oosting 2002; Ricci 2000; Tan 1996; Terreehorst 2005), ranging from 20 to 86 participants per study. Colloff 1989 randomised 23 participants into four groups, resulting in only four to six participants per group. Eczema is a relatively common condition, especially in childhood, so it is surprising not to have found a larger study on house dust mite reduction and avoidance measures for the treatment of eczema.

Setting

Details about the setting for the use of the interventions in the studies was very clear and was the same for all seven: The study interventions were all used in the participant's own homes.

Five out of the seven studies reported details of the setting of recruitment and the location of follow-up assessments (Colloff 1989; Endo 1997; Oosting 2002; Tan 1996; Terreehorst 2005). Four studies recruited from secondary care, and one study recruited from both the community (primary care), using an article in the press, and secondary care (Oosting 2002).

Participants

All of the seven studies gave details about the age of the included participants, which ranged from two to 65 years old. Two of the studies were on children from three to 12 years old and two to 10 years old (Endo 1997; Ricci 2000, respectively); one study, Gutgesell 2001, looked at adults aged 18 to 30 years old; and four studies looked at children and adults aged seven to 65 years old (Tan 1996), eight to 50 years old (Oosting 2002; Terreehorst 2005), and 12 to 47 years old (Colloff 1989). All of the seven studies stated that the participants must have atopic eczema, but only five studies reported the method of diagnosis (Colloff 1989; Endo 1997; Oosting 2002; Ricci 2000; Terreehorst 2005); three of these trials required the participants to fulfil the criteria of Hanifin and Rajka.

Outcomes

Six of the seven included studies reported outcomes that measured the severity of eczema (Colloff 1989; Endo 1997; Gutgesell 2001; Oosting 2002; Ricci 2000; Tan 1996), but only four of them used a named severity scale (SCORAD; Six Area, Six Sign Atopic Dermatitis (SASSAD); or the Leicester Sign Score (LSS)) (Gutgesell 2001; Oosting 2002; Ricci 2000; Tan 1996). Only one study (Terreehorst 2005) measured quality of life; however, as this study used the SF-36 form (which measures generic quality of life), we could not analyse the data for this review. Four studies out of the seven measured specific serum IgE to house dust mite (Colloff 1989; Endo 1997; Gutgesell 2001; Oosting 2002). One study, Gutgesell 2001, recorded both the amount of topical corticosteroids used and participant-rated global eczema severity.

Interventions

Of the seven included studies, four looked at complex house dust mite reduction and avoidance interventions (Colloff 1989; Gutgesell 2001; Ricci 2000; Tan 1996), with most interventions aiming to reduce the numbers of house dust mites. Two studies studied bedding encasings only (Oosting 2002; Terreehorst 2005), and one study, Endo 1997, compared different levels of vacuum suction power as the only variable. In total, five of the seven studies included bedding or mattress encasings as part of a complex intervention or on their own (Gutgesell 2001; Oosting 2002; Ricci 2000; Tan 1996; Terreehorst 2005). Four studies included vacuuming (Colloff 1989; Endo 1997; Ricci 2000; Tan 1996). Three studies looked at the use of mite-killing (acaricide) sprays, one containing natamycin (Colloff 1989) and the other two containing tannic acid and benzyl benzoate (Gutgesell 2001; Tan 1996). One study (Ricci 2000) compared a strict routine of dust reduction and avoidance measures, which comprised the use of mattress and pillow encasings, vacuuming of the bedroom and living room carpets twice a week, other carpets vacuumed once a week or removed, removal or washing of soft toys once a week, and hot washing of bedding once a week compared with normal cleaning habits. Another study, Endo 1997, used some standardised house dust mite reduction measures for both groups.

Excluded studies

We excluded 290 studies from the review by screening the title or abstract. Most of these assessed house dust mite reduction and avoidance measures but did not involve people with eczema. Of the 19 full papers that we obtained and scrutinised, we excluded eight. The reasons for exclusion were as follows: no randomisation, no comparative intervention, and not testing house dust mite reduction and avoidance measures (see the 'Characteristics of excluded studies' tables).

We eventually excluded Holm 2001 because although the study fitted all the review inclusion criteria, it did not mention whether it had randomised the participants. Contact from the authors confirmed that they had not randomised participants to treatment (Acknowledgements). Therefore, we excluded the study.

Risk of bias in included studies

Please see Figure 4 for the 'Risk of bias' summary. This gives our judgements about each 'Risk of bias' item for each included study. Overall, the included studies have a high risk of bias.

Figure 4.

'Risk of bias' summary: review authors' judgements about each 'Risk of bias' item for each included study

Allocation

None of the seven included studies provided details about the method of generating the allocation sequence.

Only one of the seven studies, Terreehorst 2005, gave any information at all about the concealment allocation sequence. This study described a process of remote randomisation and dispensing of the intervention to the participants, which makes it highly unlikely that any of the study personnel or participants could have known or predicted the allocation sequence. With so little information about the concealment of allocation to treatment for the other six studies, the risk of selection bias was judged unclear for this domain.

Blinding

All seven included studies reported that blinding took place; however, information about the methods of blinding and who were blinded are all missing or so brief that it was impossible to make a judgement on the potential for performance bias. Considering that the participants of the studies nearly always had to perform the intervention themselves or have encasings on their bed, it would seem highly unlikely that they were truly blinded in any of the included studies, even if this had been attempted. Only three studies reported that they blinded the person who assessed the eczema severity outcome to the treatment allocation and therefore had a lower risk of detection bias (Gutgesell 2001; Ricci 2000; Tan 1996).

Incomplete outcome data

None of the included studies reported using intention-to-treat principles for the analysis, and four studies reported a lower number of participants analysed compared with the number of participants randomised (Colloff 1989; Endo 1997; Oosting 2002; Tan 1996). Of particular concern was the difference in the number of withdrawals between the intervention groups in one study (Tan 1996), where 2/30 withdrew from the active intervention group using mite impermeable encasings, acaricide spray, and high-filtration vacuuming compared with 10/30 for the comparative intervention of cotton encasings, placebo spray, and low-filtration vacuuming. Only those that completed this study were analysed.

Selective reporting

Most of the trials had a high risk of bias for selective reporting, such as outcomes not being compared between groups, subgroup results being given inappropriate prominence, or stated outcomes not being reported in the results.

Other potential sources of bias

We attempted to contact authors of all the included studies, but were only successful in obtaining additional information for Terreehorst 2005 and Tan 1996.

The data on many of the participants in Terreehorst 2005 had previously been published in 2003, which we listed as a secondary reference to this included study. This previous trial report had stated that all participants were encouraged to hot wash the bedding weekly, which could have masked any beneficial effects of the encasings.

We were able to find additional information about Oosting 2002 in a letter to the editor and a subsequent reply in 2003, which we listed as secondary references to this included study.

In the trial by Colloff 1989, the definition of eczema 'classic clinical features and chronic relapsing course of atopic dermatitis' was very wide, raising the possibility that not all participants had eczema. Endo 1997 diagnosed atopic eczema according to the criteria of Hanifin and Rajka, and baseline severity of eczema was comparable between groups. Gutgesell 2001 did not report any details of the definition of eczema. Ricci 2000 described the inclusion criterion as 'the extrinsic variant of AD, i.e. raised serum total IgE antibodies and/or the presence of specific IgE antibodies to foods or inhalant allergens'. Tan 1996 did not state the method of diagnosis of eczema. It was also stated that there were more participants with severe eczema in one group than the other. Terreehorst 2005 and Oosting 2002 defined eczema according to the Hanifin and Rajka criteria.

Effects of interventions

See: Summary of findings for the main comparison

As many of the included studies looked at differing complex interventions, we discuss the results of all the seven included studies narratively. As none of the studies looked at the same outcomes for the same or similar interventions, it was not possible to combine studies in a meta-analysis. Four included studies assessed our primary outcome, 'Clinician-assessed global eczema severity using a named scale (e.g., SCORing Atopic Dermatitis (SCORAD)) or modification of such a scale', and one included study assessed our primary outcome of 'Participant- or caregiver-assessed eczema-related quality of life using a named instrument'.

One included study assessed our secondary outcome of 'Participant- or caregiver-assessed global eczema severity score'. One included study assessed our secondary outcome of 'Amount and frequency of topical treatment required'. Four included studies assessed our secondary outcome of 'Sensitivity to house dust mite allergen using a marker (e.g., specific IgE)'. We did not find any adverse events associated with house dust mite reduction and avoidance methods in the included studies, so we could not address our secondary outcome of 'Adverse effects'.

Primary outcomes

Clinician-assessed global eczema severity using a named scale (e.g., SCORing Atopic Dermatitis (SCORAD)) or modification of such a scale

Two studies measured the severity of eczema using SCORAD. Gutgesell 2001 found no statistically significant difference in reduction of severity after one year (P = 0.901) (non-parametric tests for tests of repeated measures) between the use of allergen impermeable polyurethane encasings and acaricide spray consisting of tannic acid and benzyl benzoate versus allergen permeable cotton encasings and placebo acaricide spray consisting of water and a trace of ethanol. The active encasings group had a reduction in SCORAD from a median (interquartile range) of 46 (37 to 55) to 40 (32 to 63), and the control encasings had a change in SCORAD from 35 (24 to 46) to 37 (30 to 45). This study did not provide many details; we abstracted the SCORAD scores from a graph, and the trial only had 20 participants in total.

The second study by Ricci and colleagues, involving 41 participants (Ricci 2000), only used comparative groups for two months. The study recorded reduction in severity within the group using the dust mite avoidance measures (a reduction from a mean of 33 to 26 SCORAD points) and also the group who used normal cleaning patterns (a reduction from a mean of 27 to 24 SCORAD points). However, despite measuring the reduction in severity, there was no comparison between the two groups.

The paper by Friedmann and colleagues, which was an additional report of the included study by Tan and colleagues involving 60 participants (Tan 1996), reported eczema severity over six months measured using the Six Area, Six Sign Atopic Dermatitis (SASSAD) severity scale, which runs from 0 to 108. A significant benefit for a complex intervention of a GORE-TEX® bedding system combined with benzyltannate spray and high-filtration vacuuming was reported. The mean difference in the mean severity scores were -12.6 in the active treatment group and -4.2 in the control group. The analysis of the differences in the reduction in severity scores between groups used analysis of covariance with initial eczema scores and logs of the initial mattress dust weight and bedroom carpet Dermatophagoides pteronyssinus (Der) p1 concentration as covariates and reported a mean difference of 4.2 (95% confidence interval (Cl) 1.7 to 6.7), P = 0.008 (unpaired student's t-test), in favour of the GORE-TEX® bedding system, benzyltannate spray, and high-filtration vacuuming.

The trial by Oosting and colleagues, involving 86 participants (Oosting 2002), measured eczema severity using the Leicester Sign Score (LSS) (median and range) over one year and found significant reductions in severity, extent, and itching scales of the LSS within the active treatment group (LSS disease activity 17 (6 to 60) to 13 (0 to 55), P = 0.017) (LSS extent 19.5 (3 to 88) to 14.5 (0 to 87), P = 0.038) (LSS itching score mm 73.5 (0 to 100) to 63 (4 to 100), P = 0.045), but did not report the total LSS scores. The trial report mentions that there were no significant between-group differences, but does not report any more detail.

Participant- or caregiver-assessed eczema-related quality of life using a named instrument

Only one study, involving 64 participants (Terreehorst 2005), measured quality of life. As a generic self assessment of physical and emotional health scale, SF-36 was used, which does not specifically ask about eczema-related quality of life; it was not directly relevant to this review. No significant differences were found between using mite impermeable encasings or permeable encasings.

Secondary outcomes

Participant- or caregiver-assessed global eczema severity score

One study, Gutgesell 2001, recorded participant-assessed skin status using a visual analogue scale. The study found no significant statistical difference between allergen impermeable encasings and acaricide spray consisting of tannic acid and benzyl benzoate compared with allergen permeable cotton encasings and placebo acaricide spray of water with a trace of ethanol. There were only 20 participants. There were no detailed data for this outcome, and there is not enough information to be sure if the participants were blinded in the report.

Amount and frequency of topical treatment required

Again, only one study, Gutgesell 2001, recorded the amount of topical corticosteroid used. This was recorded by weighing the amount of cream or ointment left in the participant's steroid containers at the end of the study. No significant difference was found between the amount of topical corticosteroid used in each group (P = 0.624) (exact Wilcoxon test), but the study did not report detailed data.

Sensitivity to house dust mite allergen using a validated marker (e.g., specific IgE)

Four of the seven studies assessed sensitivity to house dust mite using different methods (Colloff 1989; Endo 1997; Gutgesell 2001; Oosting 2002).

One study, involving 23 participants (Colloff 1989), did not analyse between-group differences. Within-group analyses showed statistically significant reductions in serum house dust mite (Dermatophagoides pteronyssinus (D. pteronyssinus))-specific IgE for vacuuming in combination with natamycin treatment (P < 0.05). Vacuuming in combination with placebo treatment also provided significant reductions in serum total IgE (P < 0.05) and serum house dust mite (D. pteronyssinus)-specific immunoglobulin G (IgG) (P < 0.01) after 12 weeks. Analysis of the treatment effects were carried out using t-tests.

One study, involving 30 participants (Endo 1997), did not find any significant differences (no between-group statistical tests reported) between the intervention groups, which compared full power vacuuming against half power vacuuming for both total and house dust mite (D. pteronyssinus and Dermatophagoides farina)-specific IgE levels after one year.

Oosting 2002, which included 86 participants, did not show any significant difference between the intervention groups for house dust mite-specific IgE levels after one year (-2.15, -58.5 to 44.6 for placebo compared with -2.15, -30.2 to 33.9). No statistical comparison between the groups was reported, but the difference was described as not significant. The final study, involving 20 participants (Gutgesell 2001), also did not find any significant difference in the house dust mite-specific IgE levels (statistical data were not reported) between the intervention groups after one year.

Adverse effects

None of the seven included studies reported recording adverse events. We managed to contact one author, who confirmed that no adverse events related to the use of encasings had occurred.

Discussion

Summary of main results

The small amount of data on the severity of eczema measured using SCORAD in two studies do not present any evidence for a significant benefit of the use of mite impermeable mattress encasings and acaricide spray over placebo (mite permeable encasings) and house dust mite reduction-cleaning practices compared with normal cleaning patterns. One study, involving 60 participants (Tan 1996), which measured the change in eczema severity using SASSAD over six months, found a modest but statistically significant benefit of a GORE-TEX® bedding system combined with benzyltannate spray and high-filtration vacuuming. This study also reported a 98% reduction in the number of mites in the active treatment group.

None of the included studies reported investigator-assessed global measures of eczema severity. There were little data on participant-assessed eczema severity, with one small study of 20 participants, Gutgesell 2001, finding no significant difference between allergen impermeable encasings and acaricide spray versus placebo (cotton encasings and water spray with a trace of ethanol) after two months.

There is no evidence of benefit through reduction in sensitivity to house dust mite, with four studies (159 participants) finding no significant difference in the level of sensitisation to house dust mite between treatment groups. Two out of four trials did not statistically compare the results between treatment groups for this outcome.

None of the included studies looked at eczema-related quality of life.

Overall completeness and applicability of evidence

All the included studies found for this review are lacking some information about trial methodology and detailed data for some of the reported outcomes, especially numbers of participants included in the analyses. Several did not compare the outcome data between the two treatment groups, leaving readers guessing as to the clinical meaning of the results. The relevance of the change in level of house dust mite sensitivity levels in individuals compared with clinical benefits is obscure.

Quality of the evidence

Nearly all of the included studies were for an unacceptably short period of time for a long-term chronic condition like eczema. However, as they were mostly investigating interventions with previous evidence of benefit in eczema, it is likely that only short-term studies would have received ethical approval. There is mostly not enough detail about the interventions carried out to reproduce them, and for most of the trials, there was not enough information about the study population, especially in terms of the details of the eczema diagnosis and severity. Collectively, these factors mean that the evidence is of very low quality. Although the small studies in this review do not seem to provide much evidence to suggest that house dust mite reduction has any beneficial effect on eczema or atopic eczema, they also do not provide much evidence of no benefit. There have not yet been any studies that are both methodologically robust and long enough to be reasonably sure of seeing any beneficial effects, which may be slow to develop.

Potential biases in the review process

We have taken care to try and eliminate bias from this review; however, it is always possible, although unlikely, that one or more trials have been missed, buried in journals not covered by the review search or buried in a journal's correspondence section. With such little data in the review at present, any missing trials have a greater potential to change the review conclusions.

Agreements and disagreements with other studies or reviews

Three clinical guidelines and two systematic reviews have looked at whether house dust mite reduction and avoidance measures are effective for the treatment of eczema (AAD 2003; Hoare 2000; Langan 2006; NICE 2007; SIGN 2011). A review of the potential 'flare factors' for eczema, Langan 2006, briefly summarised the RCTs that have assessed the efficacy of house dust mite reduction and avoidance measures. This review concluded that there was not enough high-quality evidence to determine whether house dust mite reduction and avoidance measures are effective. The NICE guidelines concluded that there was some evidence of benefit from house dust mite reduction measures in adults and children after two to six months of treatment (NICE 2007), although it does point out that there is still room to ask about both the effectiveness and cost-effectiveness of such intensive interventions given the potential degree of clinical improvement. The American Academy of Dermatology (AAD) technical report summarised trials of house dust mite reduction (AAD 2003), and AAD guidelines based on the technical report (Hanifin 2004) stated that there was not enough evidence to make recommendations about avoidance of house dust mite. The systematic review by Hoare and colleagues reported that the small, poorly reported trials found did not provide any convincing evidence about reduction of house dust mite measures and recommended pragmatic single intervention trials for future research (Hoare 2000).

Authors' conclusions

Implications for practice

There can be little confidence in the observed beneficial effect on severity of eczema (measured using SASSAD) in one small, very low-quality (GRADE approach) trial. As this treatment response has only been seen in those with atopic eczema, with specific sensitivity to one or more aeroallergens, its use in the eczema population as a whole is unknown. This trial also reported a high reduction in the level of mites in the treatment group, which agrees with suggestions from trials in allergic rhinitis (Nurmatov 2012): that it is only a very significant eradication of house dust mites that produces a clinically significant effect for eczema. The potential benefit from a small magnitude of effect needs to be weighed against the impact of sustaining the intervention regimen over long periods of time.

As none of the trials included in this review measured participant- or physician-assessed eczema-related quality of life, there is currently no evidence about the impact of house dust mite reduction and avoidance measures on people with eczema.

As many as a third of people with eczema who have a positive test for allergy to house dust mite have reported worsening of eczema or respiratory symptoms when exposed to dust. Four trials, three of which had atopic participants and a fourth that did not require sensitivity to allergens as an inclusion criterion, did not find any evidence of a reduction in the specific sensitivity to house dust mites over one year. This evidence hints that a 'home only' approach to dust mite eradication or reduction is ineffective with regard to the reduction of sensitivity to house dust mite in the eczema population. It is also not clear whether this reduction in a positive reaction to a skin prick test is a poor predictor of a clinically relevant allergy to house dust mite.

Many of the included trials used multiple different interventions simultaneously; however, the separate tasks themselves were not particularly onerous. It is plausible that families would be willing to use these interventions to see improvements in eczema. Where the interventions are particularly complex or intensive for parents and carers, there is potential for difficulties, such as lack of compliance and pressure on time, finances, and emotional energy.

The evidence available for house dust mite reduction and avoidance measures falls far short of a basis for influencing clinical practice.

Implications for research

No significant clinical benefit of any house dust mite reduction or avoidance interventions lasting long enough to be satisfactory to those with a long-term chronic condition such as eczema has yet been shown. The included studies have so far lacked methodological clarity, which leads to a lack of certainty about the modest positive results shown. Any future trials on reduction of house dust mite need to address the impact on eczema-related quality of life. Future trials on reduction or avoidance of house dust mite for treating eczema are worth pursuing. Such trials should test a clearly reported single intervention against an appropriate comparator, such as a standard care package, only in order to be clear about which of the many candidate interventions are worth testing further. The eczema trial populations should be well characterised, and trials should provide at least a year of treatment with additional long-term follow up.

Acknowledgements

This review presents independent research commissioned by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research funding scheme (RP-PG-0407-10177). The views expressed in this review are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.

The authors wish to thank Annika Scheynius, personal communication 10 January 2013, with regard to the study by Holm 2001; Peter Friedmann, personal communication 23 May 2012, with regard to the study by Tan 1996; and Ingrid Terreehorst, personal communication, with regard to her study published in 2005 (Terreehorst 2005).

The Cochrane Skin Group editorial base wishes to thank Michael Bigby, who was the Cochrane Dermatology Editor for this review; Jo Leonardi-Bee, who was the Statistical Editor; Philippa Middleton, who was Methods Editor; the clinical referees, Peter Lio and Eric Simpson; and the consumer referee, Anjna Rani.

CRG Funding Acknowledgement

The National Institute for Health Research (NIHR) is the largest single funder of the Cochrane Skin Group. 

Data and analyses

Download statistical data

This review has no analyses.

Appendices

Appendix 1. CENTRAL (The Cochrane Library) search strategy

#1 atopic dermatitis OR atopic eczema OR eczema* OR neurodermatitis OR infantile eczema
#2 child* eczema* OR Besnier's prurigo
#3 MeSH descriptor: [Neurodermatitis] explode all trees
#4 MeSH descriptor: [Eczema] explode all trees
#5 (dust mite*) or (Dermatophagoide* or Euroglyphus or Blomia or Pyroglyphidae)
#6 MeSH descriptor: [Pyroglyphidae] explode all trees
#7 MeSH descriptor: [Dermatitis, Atopic] 1 tree(s) exploded
#8 SR-SKIN
#9 #5 or #6
#10 #1 or #2 or #3 or #4 or #7
#11 #9 and #10
#12 #11 and not #8

Appendix 2. MEDLINE (Ovid) search strategy

1. randomized controlled trial.pt.
2. controlled clinical trial.pt.
3. randomized.ab.
4. placebo.ab.
5. clinical trials as topic.sh.
6. randomly.ab.
7. trial.ti.
8. 1 or 2 or 3 or 4 or 5 or 6 or 7
9. (animals not (human and animals)).sh.
10. 8 not 9
11. exp Dermatitis, Atopic/
12. atopic dermatitis.mp.
13. atopic eczema.mp.
14. exp NEURODERMATITIS/
15. neurodermatitis.mp.
16. infantile eczema.mp.
17. childhood eczema.mp.
18. Besniers' Prurigo.mp.
19. exp Eczema/ or eczema.mp.
20. 16 or 11 or 19 or 14 or 13 or 17 or 12 or 15 or 18
21. 10 and 20
22. exp Pyroglyphidae/
23. (house dust mite$ or housedust mite$).mp.
24. Dermatophagoide$.mp.
25. Euroglyphus.mp.
26. Blomia.mp.
27. dust mite$.mp.
28. exp Mites/
29. 22 or 23 or 24 or 25 or 26 or 27 or 28
30. 21 and 29

Appendix 3. Embase (Ovid) search strategy

1. random$.mp.
2. factorial$.mp.
3. (crossover$ or cross-over$).mp.
4. placebo$.mp. or PLACEBO/
5. (doubl$ adj blind$).mp.
6. (singl$ adj blind$).mp.
7. (assign$ or allocat$).mp.
8. volunteer$.mp. or VOLUNTEER/
9. Crossover Procedure/
10. Double Blind Procedure/
11. Randomized Controlled Trial/
12. Single Blind Procedure/
13. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12
14. exp Dermatitis, Atopic/
15. atopic dermatitis.mp.
16. atopic eczema.mp.
17. exp NEURODERMATITIS/
18. neurodermatitis.mp.
19. infantile eczema.mp.
20. childhood eczema.mp.
21. Besniers' Prurigo.mp.
22. exp Eczema/ or eczema.mp.
23. 19 or 14 or 22 or 17 or 16 or 20 or 15 or 18 or 21
24. exp Pyroglyphidae/
25. (house dust mite$ or housedust mite$).mp.
26. Dermatophagoide$.mp.
27. Euroglyphus.mp.
28. Blomia.mp.
29. dust mite$.mp.
30. exp Mites/
31. 24 or 25 or 26 or 27 or 28 or 29 or 30
32. 13 and 23 and 31

Appendix 4. LILACS search strategy

(atopic$ or eczema$ or eccema or neurodermatitis or prurigo) and (dust or mite$ or acaro or acarido)

What's new

DateEventDescription
18 May 2016AmendedSearches of CENTRAL, MEDLINE, PubMed and Embase in May 2016 did not find any relevant new trials. Thus, an update has not been considered necessary at this time. Our Information Specialist will run a new search in 2017 to re-assess whether an update is needed.

History

Protocol first published: Issue 3, 2010
Review first published: Issue 1, 2015

DateEventDescription
3 February 2016AmendedAuthor information (affiliation) updated.

Contributions of authors

Link with editorial base and co-ordination of contributions from co-reviewers (HN)
Draft protocol (HN, with contributions from all)
Run search (HN)
Identify relevant titles and abstracts from searches (HN and EP)
Obtain copies of trials (HN, EP, with contributions from all)
Selection of trials (HN, EP, RB, and HW)
Extract data from trials (HN, and EP)
Enter data into RevMan (HN, and EP)
Carry out analysis (HN, LR, and EP)
Interpret data (HN, EP, RB, LR, and HW)
Draft final review (HN, with contribution from all)
Update review (HN)

Disclaimer

The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the NIHR, NHS or the Department of Health, UK.

Declarations of interest

Helen Nankervis: nothing to declare.
Emma V Pynn: nothing to declare.
Robert J Boyle: "I am a co-investigator on a new trial of temperature controlled laminar airflow for treating atopic eczema http://www.hra.nhs.uk/news/research-summaries/temperature-controlled-laminar-airflow-in-severe-paediatric-eczema/. This is an allergen avoidance study taking place at Imperial College, in children and adolescents with severe eczema."
Lesley Rushton: nothing to declare.
Hywel C Williams: nothing to declare.
Deanne M Hewson: nothing to declare.
Thomas Platts-Mills: nothing to declare.

Sources of support

Internal sources

  • Centre of Evidence Based Dermatology, UK.

    Support and guidance

External sources

  • The National Institute for Health Research (NIHR), UK.

    The NIHR, UK, is the largest single funder of the Cochrane Skin Group.

Differences between protocol and review

The primary outcomes both stated in the protocol that the severity scales used had to be named and validated. The reality is that with so little data available for the primary outcomes and the difficulty with defining whether an outcome severity scale has been suitably validated, we removed the requirement for validated severity scales.

In the protocol, we had stated that we would search excluded studies for adverse effects. We removed this statement as by definition, they would not be relevant for this review.

Notes

Searches of CENTRAL, MEDLINE, PubMed and Embase in May 2016 did not find any relevant new trials. Thus, an update has not been considered necessary at this time. Our Information Specialist will run a new search in 2017 to re-assess whether an update is needed.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Colloff 1989

MethodsRandomised parallel group (4-arm)
Participants

Inclusion criteria

  • people with clinical features and chronic, relapsing course of atopic dermatitis

  • with a positive immediate skin prick response to house dust mite extract

  • confirmed positive by RAST to anti-HDM

  • elevated total IgE

The study randomised 23 participants, but did not report how many were randomised to each group

Interventions
  • only in bedrooms, only 1 pillow per bed - vacuuming of upper surfaces of mattress and both sides of the pillow just before natamycin spray; natamycin spray (625 mg for a single bed, 1250 mg for a double bed) on upper surfaces of mattresses and both sides of the pillow; placebo

  • The combinations of interventions in the 4 arms of the trial were as follows: natamycin and vacuuming; natamycin and no vacuuming; placebo spray and vacuuming; placebo spray and no vacuuming

Duration: 4 months

Outcomes
  • Eczema severity (scale not named or validated)

  • RAST for IgE or IgG to house dust mite (D. pteronyssinus)

Notes-
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe study gave no details beyond "randomly allocated"
Allocation concealment (selection bias)Unclear riskThe study gave no details about whether this was done
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskThe study provided no details about the blinding of participants or personnel
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskThe study gave no details about the blinding of outcome assessments
Incomplete outcome data (attrition bias)
All outcomes
High riskThe study did not include participants who withdrew in the final analysis. (20/23 participants were included in the analysis: natamycin and vacuuming group = 6; natamycin and no vacuuming group = 4; placebo spray and vacuuming group = 5; placebo spray and no vacuuming = 5)
Selective reporting (reporting bias)Unclear riskThere were no details of any prespecified outcomes reported
Other biasHigh riskThe definition of eczema, 'classic clinical features and chronic relapsing course of atopic dermatitis', was very wide, raising the possibility that not all participants had eczema

Endo 1997

MethodsRandomised, blinded parallel group (2-arm), single-centre
Participants

Inclusion criteria

  • children with moderate stable atopic eczema based on the Hanafin and Rajka criteria for more than 1 month

  • a positive (more than class 2) RAST to house dust mite

The study randomised 30 participants in total

Interventions
  • full power vacuuming (n = 15) versus low power (40% to 55% of full power) vacuuming (n = 15) of floors, quilt covers, and mattresses performed every day by the participants and every 3 weeks by study investigators

Duration: for a period of 1 year

Outcomes
  • Eczema severity (trial authors' own scoring system)

  • Serum-specific IgE to house dust mite (Der f, Der p)

  • Total serum IgE, mite counts in floors, quilts, and mattresses

NotesThe report was written in Japanese
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe study gave no information about this
Allocation concealment (selection bias)Unclear riskThe study gave insufficient details
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskThe report stated that the doctors and participants did not know to which group the participants were allocated
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskThe study gave no details
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskThe study did not include in the analyses outcome data for 2/30 (7%) participants lost to follow up
Selective reporting (reporting bias)High riskThe study did not compare the data from the groups, only the data within each group
Other biasLow riskThe study diagnosed atopic eczema according to the criteria of Hanifin and Rajka; baseline severity of eczema was comparable

Gutgesell 2001

MethodsRandomised parallel group (2-arm)
Participants

Inclusion criteria

  • aged 18 to 30

  • moderate to severe atopic eczema (method of diagnosis not stated)

  • positive RAST class 3 or above

  • specific IgE to Der p

  • more than 2 mg per g of dust in the mattress

The study randomised 20 participants in total

Interventions
  • allergen impermeable polyurethane encasings and acaricide spray versus cotton permeable encasings and water spray with traces of ethanol

The study did not report the number of participants randomised to each group

Outcomes
  • Severity of eczema (SCORAD)

  • Participant-assessed skin status (visual analogue scale)

  • Specific IgE to Der p

  • Amount of corticosteroid used (weight of treatment tubes)

Notes-
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe study gave no information about the generation of the randomisation sequence
Allocation concealment (selection bias)Unclear riskThe study gave no information about concealment of the allocation sequence
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskThere were no details about who was blinded, except for the evaluating physician
Blinding of outcome assessment (detection bias)
All outcomes
Low riskThe evaluating physician was not aware of the allocation of treatment to the participants
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants completed the study and were included in the analysis
Selective reporting (reporting bias)Low riskAll planned outcomes had their results reported
Other biasUnclear riskThe study reported no details of the definition of eczema

Oosting 2002

MethodsRandomised parallel group (2-arm)
Participants

Inclusion criteria

  • atopic eczema diagnosis according to criteria of Hanifin and Rajka

  • 0.7 or above RAST for house dust mite, skin test index, or both

  • 200 ng per gram or over of dust in the mattress (Der p1 or Der f1)

The study randomised 86 participants to treatment

Interventions
  • GORE-TEX® bedding system (mattress, pillow, and duvet encasings), placebo (cotton) bedding system (mattress, pillow, and duvet encasings)

  • The frequency with which the interventions were performed was not reported

Duration: The interventions were given for 1 year

Outcomes
  • Severity of eczema (Leicester Sign Score)

  • Participant-assessed itching and sleeplessness (VAS)

  • Sensitivity to house dust mite allergen (intradermal test, serum-specific IgE to Der p1, atopy patch test)

  • Total serum IgE

  • Total eosinophil count

NotesThe study measured levels of dust and Der p1, but they did not appear to be prespecified outcomes
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe study gave no information about generation of the randomisation sequence
Allocation concealment (selection bias)Unclear riskThe study reported no information about allocation concealment
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskThe study gave no information except that the nurses taking the dust samples were blinded to treatment allocation. The study stated double-blind, but did not report details reported
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskThe study gave no information about blinding the outcome assessment
Incomplete outcome data (attrition bias)
All outcomes
High riskThe numbers for the analysis were lower than the number of participants randomised (73/86 participants)
Selective reporting (reporting bias)High riskPlacebo outcome changes were greater in some instances, but the trial report did not mention this
Other biasLow riskEczema definition was according to the criteria of Hanifin and Rajka

Ricci 2000

MethodsRandomised 2-arm trial (design not clear)
Participants

Inclusion criteria

  • aged 2 to 10 years

  • diagnosed with atopic eczema according to the Hanifin and Rajka criteria

  • all had raised total IgE antibodies to food or inhalant allergens or a positive skin prick test for food or inhalant allergens

The study randomised 41 participants in total

Interventions
  • 1 group (n = 21) were instructed to clean as per the following list: mattress and pillow encasings, hot wash of bedding once a week, living room and bedroom vacuumed at least twice a week, soft toys taken out of the bedroom or washed at least once a week, carpets vacuumed at least once a week/removed, no pets

  • Another group (n = 20) were given no specific instructions for 2 months, then they were instructed to follow the same protocol as the other group (as above)

Outcomes
  • Severity of eczema (SCORAD)

Notes-
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe study gave no information about generation of the randomisation sequence
Allocation concealment (selection bias)Unclear riskThe study reported no information about allocation concealment
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskIt would probably have been impossible to blind the participants
Blinding of outcome assessment (detection bias)
All outcomes
Low riskThe study blinded investigators doing clinical assessments. The personnel who took the dust samples were not told about the trial
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskThe study did not report the final numbers of participants analysed
Selective reporting (reporting bias)High riskThe study did not perform between-group analyses, only within groups
Other biasUnclear riskThe study described the inclusion criterion as 'the extrinsic variant of AD, i.e. raised serum total IgE antibodies and/or the presence of specific IgE antibodies to foods or inhalant allergens'

Tan 1996

MethodsRandomised, blinded parallel (2-arm) group
Participants

Inclusion criteria

  • atopic eczema

  • aged 7 to 65 years

  • at least 1 positive immediate response to aeroallergen prick test (Der p1, cat, or grass)

The study randomised 60 participants in total

Interventions
  • allergen impermeable GORE-TEX® encasings, a tannic acid and benzoate acaricide spray and high-filtration vacuum cleaner (n = 30) versus mite permeable cotton encasings, water with a trace of alcohol spray, and a low-filtration vacuum cleaner (n = 30)

Outcomes
  • Severity of dermatitis score (description matched SASSAD, but not named as such)

  • Body surface area affected

Notes-
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe study gave no information
Allocation concealment (selection bias)Unclear riskThe study gave no information
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskThe report stated 'double blind', but gave no information about whether this included participants, personnel (other than the outcome assessor), or both
Blinding of outcome assessment (detection bias)
All outcomes
Low riskThe study reported that the evaluating physician (severity of eczema) was not aware of the randomisation status of the participants
Incomplete outcome data (attrition bias)
All outcomes
High riskThe study only included in the final analyses participants who finished the study. Therefore, 28/30 in the mite impermeable encasing group and 20/30 in the mite permeable encasings group were analysed
Selective reporting (reporting bias)High riskThe groups differed in severity at baseline, but this was not really dealt with in the analysis. The study gave much weight to the results of a subgroup analysis, but it is not clear whether this was stated a priori. Also, the study reports analysis of the difference between groups for this subgroup analysis as significant, but the confidence interval crosses 0
Other biasUnclear riskThe study did not state the method of diagnosis of eczema, but stated there were more participants with severe eczema in one group than the other

Terreehorst 2005

  1. a

    anti-HDM = anti-house dust mite.
    Der f/f1 = Dermatophagoides farinae.
    Der p/p1 = Dermatophagoides pteronyssinus.
    IgE = immunoglobulin E.
    IgG = immunoglobulin G.
    n = number.
    RAST = radioallergosorbent test.
    VAS = visual analogue scale.

MethodsRandomised, blinded parallel (2-arm) group
Participants

Inclusion criteria

  • atopic eczema/dermatitis syndrome diagnosed according to the criteria of Hanifin and Rajka

  • aged 8 to 50

  • RAST test of 2 or more, intracutaneous skin test of 0.7 of more for house dust mite, or both

  • mattress must contain at least 200 ng Der p1 in a dust sample

The study randomised a total of 64 participants with eczema. It was not clear how many participants with eczema were in each group

Interventions
  • mite impermeable encasings for mattress, pillow, and duvet and mite permeable encasings for mattress, pillow, and duvet

Outcomes
  • Quality of life (SF 36) generic self assessment of physical and emotional health

Notes-
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe paper reported no details
Allocation concealment (selection bias)Low riskThere was a clear description of a remote procedure that prevented the physicians and participants being able to gain access to or predict the randomisation sequence
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskThe paper provided a description of 'double blind', but reported very little detail
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskThe study blinded the clinician, but did not provide enough information in the trial report to assess whether the participants, who recorded the data for the subjective outcomes, were also blinded, and because of the nature of the different interventions, it seems likely that this was not possible
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskThe study analysed only 89/113 and 93/111 participants from each group and did not report how many had eczema
Selective reporting (reporting bias)High riskThe study did not specify any time periods for the outcomes, so it is unclear whether the time period that the study reported for each of the outcomes matched the original trial protocol
Other biasLow riskThe eczema definition was according to the Hanifin and Rajka criteria

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
Adham 2011There was only 1 intervention group
Corver 2006This was a prevention of eczema study
D'Souza 1973This review did not cover the intervention of immunotherapy
Holm 2001The paper did not report this as being randomised, which we confirmed via contact with the senior author (Annika Scheynius)
Kim 2005The paper did not report this as being randomised
Norris 1987The intervention was not reduction or avoidance of house dust mite
Sanda 1992The paper did not report this as being randomised
Weber-Chrysochoou 2007This was not a treatment trial

Ancillary