Mono and multifaceted inhalant and/or food allergen reduction interventions for preventing asthma in children at high risk of developing asthma

 

Abstract

Background

Allergen exposure is one of the environmental factors seemingly associated with the development of asthma. If asthma is a multi-factorial disease, it is hypothesised that prevention might only prove effective if most or all relevant environmental factors are simultaneously avoided.

Objectives

To assess effect(s) of monofaceted and multifaceted interventions compared with control interventions in preventing asthma and asthma symptoms in high risk children.

Search methods

We searched the Cochrane Airways Trials Register (January 2011).

Selection criteria

Randomised controlled trials of allergen exposure reduction for the primary prevention of asthma in children. Interventions were multifaceted (reducing exposure to both inhalant and food allergens) or monofaceted (reducing exposure to either inhalant or food allergens) Follow up had to be from birth (or during pregnancy) up to a minimum of two years of age.

Data collection and analysis

We included in the analysis studies assessing the primary outcome (current diagnosis: asthma) and/or one of the secondary outcomes (current respiratory symptoms: wheezing, nocturnal coughing and dyspnoea). We pooled multifaceted and monofaceted intervention trials separately. We made an indirect comparison of their effects using tests for interaction to calculate relative odds ratios.

Main results

We included three multifaceted and six monofaceted intervention studies (3271 children). Physician diagnosed asthma in children less than five years, and asthma as defined by respiratory symptoms and lung function criteria in children aged five years and older, both favoured treatment with a multifaceted intervention compared to usual care (< 5 years: odds ratio (OR) 0.72, 95% confidence interval (CI) 0.54 to 0.96, and > 5 years: OR 0.52, 95% CI 0.32 to 0.85). However, there was no significant difference in outcome between monofaceted intervention and control interventions (< 5 years: OR 1.12, 95% CI 0.76 to 1.64, and > 5 years: OR 0.83, 95% CI 0.59 to 1.16). Indirect comparison between these treatments did not demonstrate a significant difference between multiple interventions and mono-interventions in reducing the frequency of asthma diagnosis in children under five years (relative OR 0.64 (95% CI 0.40 to 1.04, P = 0.07) or five years and older (relative OR 0.63, 95% CI 0.35 to 1.13, P = 0.12). There was also no significant difference between either mono- and multifaceted intervention and control in reducing the likelihood of symptoms of nocturnal coughing at follow up. Wheezing, however, showed a significant difference between multifaceted and mono-interventions (relative OR 0.59, 95% CI 0.35 to 0.99, P = 0.04), but the significance was lost when data on treatment only was analysed.

Authors' conclusions

The available evidence suggests that the reduction of exposure to multiple allergens compared to usual care reduces the likelihood of a current diagnosis of asthma in children (at ages < 5 years and 5 years and older). Mono-intervention studies have not produced effects which are statistically significant compared with control. In children who are at risk of developing childhood asthma, multifaceted interventions, characterised by dietary allergen reduction and environmental remediation, reduce the odds of a physician diagnosis of asthma later in childhood by half. This translates to a number needed to treat (NNT) of 17. The effect of multi-faceted interventions on parent reported wheeze was inconsistent and had no significant impact on nocturnal coughing or dyspnoea. Data from monofaceted intervention exposed children studies were not significantly different from those of control groups for all outcomes. There remains uncertainty as to whether multiple interventions are more effective than mono-component interventions. The comparisons made were indirect, making the conclusions drawn uncertain. To our knowledge there are no ongoing studies in which both intervention strategies are randomly compared. The findings, however, warrant further direct comparison between multiple- and monofaceted interventions aimed at reducing the prevalence of asthma in children.

 

Plain language summary

Mono and multifaceted allergen reducing interventions for the primary prevention of asthma in children at high risk of developing asthma

It is possible that early exposure to allergens (substances which cause allergy) may lead to development of asthma in high risk children. This review asks whether the risk of developing asthma, which is a disease caused by many factors, can be decreased by reducing single allergen levels in children with genetic susceptibility, or whether the reduction of more than one type of allergen exposure simultaneously will lead to a better outcome. As a direct comparison could not be made using current research we made indirect comparisons using trials that had compared single or multiple interventions with a control. In children who are at risk of developing childhood asthma 'multifaceted' interventions, which involve both dietary allergen reduction and environmental change to reduce exposure to inhaled allergens, reduce the odds of a doctor diagnosing asthma later in childhood by half. However, the effect of these multifaceted interventions on wheeze reported by parents was inconsistent and there was no beneficial effect on night-time coughing or breathlessness. Single ('monofaceted') interventions were not significantly more effective than controls in the reduction of all outcomes, but there remains uncertainty as to whether multiple interventions are more effective than single component interventions.

 

摘要

背景

採用單一手段(減少暴露於吸入過敏物質或引起過敏食物)與多重手段(同時減少暴露於吸入過敏物質與引起過敏食物)預防具有高度氣喘風險幼童氣喘發作

暴露於過敏原之下似乎是與引發氣喘有關的環境因子，如果氣喘是一種多重原因引發的疾病，可以假設同時迴避大多數或全部相關的環境因子可能可以有效的預防過敏。

目標

評估單一手段或多重手段的介入治療和對照治療對於預防高風險幼童氣喘發作和氣喘症狀的成效。

搜尋策略

我們檢索了Cochrane Airways Trials Register資料庫(檢索時間為2008年9月)。

選擇標準

納入針對氣喘幼童以降低暴露於過敏原為主要防護措施的隨機對照試驗，介入性治療可能是透過多重手段(同時降低暴露於吸入劑與食物過敏原之下)，或單一手段(降低暴露於吸入劑或食物過敏原之下)，所有的追蹤都是由出生(或是懷孕期間)持續至幼童至少2歲。

資料收集與分析

納入了分析試驗來評估初期成果(近期診斷：氣喘)和/或次級成果(近期呼吸症狀：喘氣、晚間咳嗽和呼吸困難)，其中集結了多手段和單一手段的介入治療試驗。並使用測試交互作用來計算相對OR值以針對不同的治療方法進行間接評估。

主要結論

納入了3個多重手段和6個單一手段的介入性治療試驗(受試者為3271位幼童)，醫師診斷幼童患有氣喘5年以下，氣喘的定義為發生在5歲以上幼童的呼吸道症狀和肺部功能症狀，兩種治療成果都傾向於多重手段的介入性治療，並且跟一般照護的效果進行比較(5歲以下的組別，OR值為0.72，95％的CI介於0.54至0.96之間，5歲以上的組別，OR值為0.52，95％的CI介於0.32至0.85之間)，在試驗成果上並沒有發現顯著差異(5歲以下的組別，OR值為0.12，95％的CI介於0.76至1.64之間，5歲以上的組別，OR值為0.83，95％的CI介於0.59至1.16之間)，針對這些方法進行直接比較並無法證明在多重介入和單一介入方法之間，對於降低5歲以下(相對OR值為0.64，95％的CI介於0.40至1.04之間，P值為0.07)或5歲以上(相對OR值為0.63，95％的CI介於0.35至1.13之間，P值為0.12)患者被診斷出患有氣喘的頻率上具有明顯差異，在將單一手段或多重手段介入與對照進行比較時發現，對於降低疑似夜間咳嗽症狀的影響也沒有顯著差異，然而，在喘氣這項數值上，兩組之間呈現顯著差異(相對OR值為0.59，95％的CI介於0.35至0.99之間，P值為0.04)，但是若只有對試驗的數據進行分析時，這樣的顯著性便會消失。

作者結論

依據可取得的數據顯示，降低暴露於多種過敏原下會比一般照護更可以降低幼童被診斷患有氣喘的可能性(在5歲以下，5歲和5歲以上)。相對於對照組來說，單一性介入治療試驗產生的效用在統計學上並不具有顯著性，在具有罹患幼年氣喘風險的幼童身上，使用降低暴露於日常過敏原或是調整環境等多手段介入性治療可以降低一半在日後幼童時期被診斷患有過敏的機率，換言之，需要針對17位受試者進行治療來減少一個受試者過敏發作，多重手段介入治療對於雙親回報出現喘氣症狀的影響並不一致，此外對於夜間咳嗽或是呼吸困難的改善也沒有顯著的影響，由單一手段介入治療的數據可以發現，在所有試驗成果上，暴露於過敏原下的幼童組和對照組並出現明顯差異的情況，因此目前對於多重手段介入治療是否比單一手段介入治療更為有效能有所疑慮，在我們的瞭解中，目前並沒有正在進行中且針對兩種介入治療策略進行隨機比較的試驗，因此應該對於多重手段和單一手段介入治療進行直接的比較，並瞭解這兩種策略對於降低幼童氣喘的盛行率的功效。

翻譯人

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

早期暴露於過敏原下可能有引發幼童氣喘的高風險。本研究探討引發氣喘發作的風險，氣喘是一種會由很多原因引發的疾病，可以藉由降低具有易感性基因(genetic susceptibility)的幼童與單一過敏原的接觸來降低幼童氣喘發作的機率，同時降低暴露於一個以上的過敏原之下可能可以獲得較佳的預防成果，因為無法利用近期的檢索資料進行直接性的比較，所以我們利用單一手段和多重手段與對照組差異的試驗來進行間接性的比較，對於具有氣喘發作風險的幼童給予同時兼顧降低日常過敏原和改變環境以降低暴露於吸入性過敏原下的多重手段介入治療可以降低一半之後醫生診斷幼童氣喘的機率，但是這些多重手段的介入性治療對於雙親回報其喘氣症狀的影響結果並不一致，此外這樣的治療方法對於夜間性咳嗽和呼吸困難的症狀也沒有幫助，單一性(單一手段)的介入治療在所有治療成果上也不會比對照組具有更顯著的效果，但是對於多重手段介入治療是否比單一手段介入治療更來得有效目前仍存有疑問。