Subcutaneous closure versus no subcutaneous closure after non-caesarean surgical procedures

  • Review
  • Intervention

Authors


Abstract

Background

Most surgical procedures involve a cut in the skin that allows the surgeon to gain access to the surgical site. Most surgical wounds are closed fully at the end of the procedure, and this review focuses on these. The human body has multiple layers of tissues, and the skin is the outermost of these layers. The loose connective tissue just beneath the skin is called subcutaneous tissue, and this generally contains fat. There is uncertainty about closure of subcutaneous tissue after surgery: some surgeons advocate closure of subcutaneous tissue, as they consider this closes dead space and leads to a decrease in wound complications; others consider closure of subcutaneous tissue to be an unnecessary step that increases operating time and involves the use of additional suture material without offering any benefit.

Objectives

To compare the benefits (such as decreased wound-related complications) and consequences (such as increased operating time) of subcutaneous closure compared with no subcutaneous closure in participants undergoing non-caesarean surgical procedures.

Search methods

In August 2013 we searched the following databases: Cochrane Wounds Group Specialised Register (searched 29 August, 2013); The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 7); Ovid MEDLINE (1946 to August Week 3 2013); Ovid MEDLINE (In-Process & Other Non-Indexed Citations August 28, 2013); Ovid EMBASE (1974 to 2013 Week 34); and EBSCO CINAHL (1982 to 23 August 2013). We did not restrict studies with respect to language, date of publication or study setting.

Selection criteria

We included only randomised controlled trials (RCTs) comparing subcutaneous closure with no subcutaneous closure irrespective of the nature of the suture material(s) or whether continuous or interrupted sutures were used. We included all RCTs in the analysis, regardless of language, publication status, publication year, or sample size.

Data collection and analysis

Two review authors independently identified the trials and extracted data. We calculated the risk ratio (RR) with 95% confidence intervals (CI) for comparing binary (dichotomous) outcomes between the groups and calculated the mean difference (MD) with 95% CI for continuous outcomes. We performed meta-analysis using the fixed-effect model and random-effects model. We performed intention-to-treat analysis whenever possible.

Main results

Eight RCTs met the inclusion criteria. Six of the trials provided data for this review and all of these were at high risk of bias. Six trials randomised a total of 815 participants to subcutaneous closure (410 participants) or no subcutaneous closure (405 participants). Overall, 7.7% of participants (63/815 of participants) developed superficial surgical site infections and there was no clear evidence of a difference between the two intervention groups (RR 0.84; 95% CI 0.53 to 1.33; very low quality evidence). Only two trials reported superficial wound dehiscence, with 7.9% (17/215) of participants developing the problem. It is not clear whether the lack of reporting of this outcome in other trials was because it did not occur, or was not measured. There was no clear evidence of a between-group difference in the proportion of participants who developed superficial wound dehiscence in the trials that reported this outcome (RR 0.56; 95% CI 0.22 to 1.41; very low quality evidence). Only one trial reported deep wound dehiscence, which occurred in 8.3% (5/60) of participants. There was no clear evidence of a difference in the proportion of participants who developed deep wound dehiscence between the two groups (RR 0.25; 95% CI 0.03 to 2.11; very low quality evidence). Three trials reported the length of hospital stay and found no significant difference between groups (MD 0.10 days; 95% CI -0.45 to 0.64; very low quality evidence). We do not know whether this review reveals a lack of effect or lack of evidence of effect. The confidence intervals for these outcomes were wide, and significant benefits or harms from subcutaneous closure cannot be ruled out. In addition, none of the trials assessed the impact of subcutaneous closure on quality of life, long-term patient outcomes (the follow-up period in the trials varied between one week and two months after surgery) or financial implications to the healthcare provider.

Authors' conclusions

There is currently evidence of very low quality which is insufficient to support or refute subcutaneous closure after non-caesarean operations. The use of subcutaneous closure has the potential to affect patient outcomes and utilisation of healthcare resources. Further well-designed trials at low risk of bias are necessary.

Résumé scientifique

Fermeture sous-cutanée par rapport à l'absence de fermeture sous-cutanée suite à une procédure chirurgicale autre que la césarienne

Contexte

La plupart des procédures chirurgicales impliquent une incision dans la peau qui permet au chirurgien d'accéder au site chirurgical. La plupart des plaies chirurgicales sont refermées entièrement à la fin de la procédure et cette revue se concentre sur ces procédures. Le corps humain possède plusieurs couches de tissus et la peau est la couche la plus supérieure. Le tissu conjonctif lâche situé juste au-dessous de la peau est connu sous le nom de tissu sous-cutané et il contient généralement de la matière grasse. Il existe une incertitude quant à la fermeture du tissu sous-cutané après l'opération : certains chirurgiens préconisent la fermeture du tissu sous-cutané, comme ils considèrent que cela referme l’espace mort et conduit à une diminution des complications; d'autres considèrent que la fermeture du tissu sous-cutané est une étape inutile qui augmente la durée de l'opération et implique l'utilisation de matériaux de suture supplémentaires sans offrir aucun bénéfice.

Objectifs

Comparer les bénéfices (tels qu'une réduction de complications de la plaie) et les conséquences (telles qu’une augmentation de la durée de l'opération) de la fermeture sous-cutanée par rapport à l'absence de fermeture sous-cutanée chez des participants subissant des procédures chirurgicales autres que la césarienne.

Stratégie de recherche documentaire

En août 2013, nous avons effectué des recherches dans les bases de données suivantes : le registre spécialisé du groupe Cochrane sur les plaies et contusions (recherche effectuée le 29 août 2013) ; le registre Cochrane des essais contrôlés (CENTRAL) (La Bibliothèque Cochrane 2013, numéro 7) ; Ovid MEDLINE (de 1946 à la 3ème semaine d'août 2013) ; Ovid MEDLINE (les citations en cours et non-indexées, 28 août 2013) ; Ovid EMBASE (de 1974 à la 34ème semaine de 2013) et EBSCO CINAHL (de 1982 au 23 août 2013). Aucune restriction n’a été appliquée concernant la langue, la date de publication ou le contexte de l'étude.

Critères de sélection

Nous avons uniquement inclus des essais contrôlés randomisés (ECR) comparant la fermeture sous-cutanée à l'absence de fermeture sous-cutanée, indépendamment de la nature du matériel (ou des matériaux) de suture ou si les sutures continues ou discontinues étaient utilisées. Nous avons inclus tous les ECR dans l'analyse, indépendamment de la langue, du statut de publication, de l’année de publication ou de la taille des échantillons.

Recueil et analyse des données

Deux auteurs de la revue ont indépendamment identifié les essais et extrait les données. Nous avons calculé le risque relatif (RR) avec un intervalle de confiance (IC) à 95% pour la comparaison des critères de jugement binaires (dichotomiques) entre les groupes et calculé la différence moyenne (DM) avec un IC à 95% pour les résultats continus. Nous avons effectué une méta-analyse en utilisant un modèle à effets fixes et un modèle à effets aléatoires. Nous avons effectué une analyse en intention de traiter lorsque cela était possible.

Résultats principaux

Huit ECR remplissaient les critères d'inclusion. Six des essais ont fourni des données pour cette revue et tous étaient à risque de biais élevé. Six essais ont randomisé un total de 815 participants pour la fermeture sous-cutanée (410 participants) ou l'absence de fermeture sous-cutanée (405 participants). Dans l'ensemble, 7,7% des participants (63/815 participants) ont développé des infections superficielles du site opératoire et il n'y avait aucune preuve probante d'une différence entre les deux groupes d'intervention (RR 0,84 ; IC à 95% 0,53 à 1,33; preuves de très faible qualité). Seuls deux essais rapportaient la déhiscence de la plaie superficielle, avec 7,9% (17/215) des participants développant le problème. Il n'est pas clair si le manque de notification de ce critère de jugement dans d'autres essais était dû au fait que le problème ne s’était pas produit ou n'avait pas été mesuré. Il n'y avait aucune preuve probante d'une différence entre les groupes dans la proportion de participants ayant développé une déhiscence superficielle de la plaie dans les essais qui rapportaient ce critère de jugement (RR 0,56 ; IC à 95 % 0,22 à 1,41 ; preuves de très faible qualité). Un seul essai rapportait une déhiscence profonde des plaies qui était survenue chez 8,3% (5/60) des participants. Il n'y avait aucune preuve probante d'une différence dans la proportion de participants ayant développé une déhiscence profonde des plaies entre les deux groupes (RR 0,25 ; IC à 95% 0,03 à 2,11; preuves de qualité très médiocre). Trois essais rapportaient la durée du séjour à l'hôpital et n'ont trouvé aucune différence significative entre les groupes (DM 0,10 jours ; IC à 95% -0,45 à 0,64 ; preuves de très faible qualité). Nous ne savons pas si cette revue révèle une absence d'effet ou un manque de preuves de l'effet. Les intervalles de confiance pour ces critères de jugement étaient larges et les effets significatifs bénéfiques ou délétères de la fermeture sous-cutanée ne peuvent pas être exclus. De plus, aucun de ces essais n’évaluait l'impact de la fermeture sous-cutanée sur la qualité de vie, les résultats des patients à long terme (la période de suivi dans les essais variait entre une semaine et deux mois après l'opération) ou les implications financières pour les donneurs de soins.

Conclusions des auteurs

Il existe actuellement des preuves de très faible qualité qui sont insuffisantes pour soutenir ou réfuter la fermeture sous-cutanée après une opération autre que la césarienne. L'utilisation de la fermeture sous-cutanée peut affecter les résultats des patients et l'utilisation des ressources médicales. D'autres essais bien conçus à faible risque de biais sont nécessaires.

Plain language summary

Stitching versus no stitching of the tissue beneath the skin (subcutaneous tissue) for non-childbirth surgery

Surgeons cut the skin in most surgical operations. Most surgical wounds are sewn up at the end of the procedure. The skin is the outermost of many layers of tissue in the human body, with subcutaneous tissue just beneath. Stitching (suturing) subcutaneous tissue after surgery is controversial. Some surgeons recommend it, claiming this decreases wound complications, while others think it is unnecessary and may increase wound complications. We investigated whether subcutaneous tissue should be sutured after non-childbirth surgery by searching the medical literature thoroughly (up to August 2013) for studies that compared subcutaneous suturing against no subcutaneous suturing. We included only randomised controlled trials - which provide the best information - reported in any language, published in any year, and with any number of participants. Two review authors independently identified trials and extracted information.

We identified six randomised controlled trials that reported one or more of the outcomes we thought were important. There may have been flaws in trial conduct that could produce incorrect results. The six trials that provided data for this review included 815 participants (410 participants had subcutaneous closure of incisions and 405 participants did not). In the trials that reported the outcomes, overall 7% of participants developed superficial wound infection, 8% of participants developed superficial separation of wounds, and 8% of participants developed deeper separation of layers in both the groups but there was no clear evidence of a difference in incidence between the subcutaneous closure group and the no subcutaneous closure group. There was no clear evidence of a difference in the length of hospital stay between the groups. We do not know whether these results indicate that there is really no difference between subcutaneous closure and no subcutaneous closure, or that there are problems with study design that make it difficult to identify true differences between the two techniques. So significant benefits or harms of subcutaneous closure cannot be ruled out. Furthermore, no trial assessed the impact of subcutaneous closure on quality of life, long-term patient outcomes (trial follow-up periods varied between one week and two months after surgery) or financial implications to healthcare providers. There is currently no evidence to support or condemn subcutaneous closure after non-childbirth surgery. Further well-designed trials are necessary.

Résumé simplifié

La suture par rapport à l'absence de suture du tissu sous la peau (tissu sous-cutané) pour la chirurgie autre que la césarienne

Les chirurgiens incisent la peau dans la plupart des opérations chirurgicales. La plupart des plaies chirurgicales sont recousues à la fin de la procédure. La peau est la couche de tissu la plus extérieure de nombreuses couches de tissu dans le corps humain, avec un tissu sous-cutané juste au-dessous. Suturer le tissu sous-cutané après la chirurgie est controversé. Certains chirurgiens le recommandent, affirmant que cela réduit les complications des plaies, alors que d'autres estiment que cela est inutile et peut accroître les complications des plaies. Nous avons tenté de déterminer si un tissu sous-cutané devrait être suturé après une chirurgie autre que la césarienne par une recherche exhaustive dans la littérature médicale (jusqu'en août 2013) pour les études qui comparaient la suture sous-cutanée à une absence de suture sous-cutanée. Nous avons uniquement inclus des essais contrôlés randomisés, qui fournissent les meilleures informations – sans restriction de langue, d’années de publication ou du nombre de participants. Deux auteurs de la revue ont indépendamment identifié les essais et extrait les informations.

Nous avons identifié six essais contrôlés randomisés qui ont rapporté un ou plusieurs critères de jugement que nous avons considéré être importants. Le déroulement des essais peut avoir certaines imperfections qui ont pu produire des résultats incorrects. Les six essais qui ont fourni des données pour cette revue incluaient 815 participants (410 participants recevaient une fermeture sous-cutanée des incisions et 405 participants n’en recevaient pas). Dans les essais qui avaient rendu compte de critères de jugement, globalement 7% des participants développaient une infection superficielle de la plaie, 8% des participants développaient une séparation superficielle de la plaie et 8 % des participants développaient une séparation plus profonde de couches, ceci dans les deux groupes, mais il n'y avait aucune preuve probante d'une différence d'incidence entre le groupe de fermeture sous-cutanée et le groupe sans fermeture sous-cutanée. Il n'y avait aucune preuve probante d'une différence dans la durée d'hospitalisation entre les groupes. Nous ne savons pas si ces résultats indiquent qu'il n’existe réellement aucune différence entre la fermeture sous-cutanée et l'absence de fermeture sous-cutanée, ou que des problèmes de plan d’étude rendent difficiles à identifier une réelle différence entre les deux techniques. Des effets bénéfiques ou délétères significatifs de fermeture sous-cutanée ne peuvent donc pas être exclus. De plus, aucun essai n'a évalué l'impact de la fermeture sous-cutanée sur la qualité de vie, les résultats des patients à long terme (les périodes de suivi des essais variaient entre une semaine et deux mois après l'opération) ou les implications financières pour les prestataires de santé. Il n'existe actuellement aucune preuve permettant d'étayer ou de réfuter la fermeture sous-cutanée après une chirurgie autre que la césarienne. D'autres essais bien conçus sont nécessaires.

Notes de traduction

Traduit par: French Cochrane Centre 15th June, 2014
Traduction financée par: Financeurs pour le Canada : Instituts de Recherche en Santé du Canada, Ministère de la Santé et des Services Sociaux du Québec, Fonds de recherche du Québec-Santé et Institut National d'Excellence en Santé et en Services Sociaux; pour la France : Ministère en charge de la Santé

Summary of findings(Explanation)

Summary of findings for the main comparison. Subcutaneous closure compared to no subcutaneous closure for non-caesarean surgery
  1. 1 The trial(s) was (were) of high risk of bias
    2 The confidence intervals overlapped 1 and either 0.75 or 1.25 or both. The number of events in the intervention and control group was fewer than 300
    3 There was severe heterogeneity as noted by the I2 statistic and the lack of overlap of confidence intervals

Subcutaneous closure compared to no subcutaneous closure for non-caesarean surgery
Patient or population: participants having non-caesarean surgery
Settings: secondary
Intervention: subcutaneous closure of incision
Comparison: no subcutaneous closure of incision
OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of participants
(studies)
Quality of the evidence
(GRADE)
Assumed riskCorresponding risk
No subcutaneous closure Subcutaneous closure
Superficial surgical site infection 83 per 1000 70 per 1000
(44 to 110)
RR 0.84
(0.53 to 1.33)
815
(6 studies)
⊕⊝⊝⊝
very low 1,2
Superficial wound dehiscence 103 per 1000 58 per 1000
(23 to 145)
RR 0.56
(0.22 to 1.41)
215
(2 studies)
⊕⊝⊝⊝
very low 1,2
Deep wound dehiscence 133 per 1000 33 per 1000
(4 to 281)
RR 0.25
(0.03 to 2.11)
60
(1 study)
⊕⊝⊝⊝
very low 1,2
Hospital stayThe mean hospital stay in the control groups was
6 days
The mean hospital stay in the intervention groups was
0.1 higher
(0.45 lower to 0.64 higher)
 434
(3 studies)
⊕⊝⊝⊝
very low 1,3
*The basis for the assumed risk is the median control group risk across studies. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: confidence interval; RR: risk ratio
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

Many people undergo surgical operations during their lives. Worldwide, an estimated 234 million surgical procedures are performed each year (Weiser 2008). In most surgical procedures, the surgeons make a cut (incision) to enable access to the tissue in which the operation is performed. Most surgical wounds are closed fully at the end of the procedure, and this review focuses on this type of wound.

The human body has multiple layers of tissues, with the skin as the outermost layer. The loose connective tissue just beneath the skin is called subcutaneous tissue, and this generally contains fat. Depending upon the depth and location of the surgical incision, other layers disrupted by surgery may include fascia (fibrous sheaths lining the muscles), muscles, the lining of body cavities, or the lining of bones.

The incidence of wound healing complications, such as surgical site infection (SSI) and wound dehiscence (wound breakdown along the incision), depends upon a variety of factors including the type of surgery, method of wound closure, underlying (systemic) illnesses of the person involved, their medications (including antibiotics to prevent wound infections and other drugs that may impair wound healing), antiseptic measures taken to prevent wound complications, and the length of follow-up (Garner 1986; Guo 2010; Le 2007; Mannien 2011; Reilly 2006; Woodfield 2009). The incidence of SSI also varies according to the classification of surgical wounds. Surgical wounds can be classified in different ways. One accepted classification that has been adopted by the Centers for Disease Prevention and Control (CDC) is to define wounds as clean, clean-contaminated, contaminated, and dirty or infected (Garner 1986). This classification is shown in Appendix 1. Postoperative surgical site infections can increase length of hospital stay and result in increased costs of healthcare (Herwaldt 2006). Impaired wound healing can lead to poor cosmesis (appearance of the wound) due to either hypertrophic scarring (enlargement and overgrowth of scar tissues) (NCBI-MeSH-Cicatrix-Hypertrophic 1993), or keloid scarring (sharply elevated, irregularly shaped, scarring that progressively enlarges and spreads to surrounding tissues) (NCBI-MeSH-keloid 2012). Impaired wound healing may also result in a decreased quality of life.

Description of the intervention

Closing the surgical wound may involve closing different layers of tissue. While it is intuitive to know that closure of the skin is necessary to ensure a closed surgical wound, the subcutaneous tissue may, or may not, be closed. If closed, the subcutaneous tissue is usually closed using absorbable sutures that are either continuous (stitches on the same thread) or interrupted (multiple, individual stitches) (Cetin 1997; Naumann 1995). Subcutaneous sutures may be used either alone, or in combination with a subcutaneous drain.

How the intervention might work

Some surgeons advocate closure of subcutaneous tissue, as they consider this results in closure of dead space, and decreases the likelihood of wound infection (Nygaard 1996) by preventing fluid collections.

Why it is important to do this review

Currently, there is no consensus, or systematic review available, regarding the method of skin closure for surgical wounds other than in caesarean sections. Systematic reviews on the method of closure of caesarean-section abdominal-wall wounds found that wound complications were reduced after closure of subcutaneous tissue (Anderson 2004; Chelmow 2004). Clearly, subcutaneous closure increases the operating time and involves the use of additional suture material. On the other hand, for caesarean sections subcutaneous closure can decrease the complications related to wound healing. The utility of subcutaneous closure, however, has not been established in non-caesarean-section surgical wounds.This review will provide guidance to the surgeons regarding the utility of subcutaneous tissue closure in non-caesarean-section surgical wounds.

Objectives

To compare the benefits (such as decreased wound-related complications) and consequences (such as longer hospital stay or increased use of suture material) of subcutaneous closure compared with no subcutaneous closure in participants undergoing non-caesarean surgical procedures.

Methods

Criteria for considering studies for this review

Types of studies

We included randomised controlled trials (RCTs), irrespective of their use of blinding, language of publication, publication status, date of publication, study setting, or sample size. We planned to include cluster-randomised controlled trials, provided that the effect estimate (risk ratio, odds ratio, or mean differences) was adjusted for the clustering effect (correlation of outcomes between subjects belonging to the same cluster). We planned to include trials in which multiple incisions in the same participant were randomised to different groups if appropriate analysis was undertaken by taking the within-subject correlation (clustering) into account, or, if it was possible to perform such an analysis from the available data. We excluded quasi-randomised studies (where the methods of allocating participants to a treatment are not strictly random, for example, date of birth, hospital record number, alternation), and other study designs.

Types of participants

People, of any age and sex, undergoing non-caesarean surgery. We have excluded caesarean operations because there is already a Cochrane review on the utility of subcutaneous closure in caesarean operations (Anderson 2004). Surgery that does not involve skin approximation (e.g. oral surgery which may involve only mucosal approximation) was also excluded.

Types of interventions

We included trials that compared subcutaneous closure with no subcutaneous closure, irrespective of the suture material (such as polyglactin, polydioxanone, polygelcaprone) or technique used (continuous or interrupted suturing). Subcutaneous drains can be used to supplement or replace subcutaneous closure to prevent fluid collecting in the dead space (Baier 2010; Cardosi 2006). Since this review is not an overview of all the possible interventions available for the management of subcutaneous tissue, we excluded trials that compared subcutaneous closure with subcutaneous drains and those that compared two different suture materials or techniques of subcutaneous closure.

Types of outcome measures

Primary outcomes
  • Surgical site infections within 30-days of surgery (we attempted to use the Centers for Disease Control and Prevention (CDC) definition, if possible (Horan 1992), or any other definition used by the trial authors). Infections were classed as:

    • superficial;

    • deep; or

    • organ space infection.

  • Wound dehiscence within 30-days of surgery (i.e. partial or complete disruption of the layers of a surgical wound (NCBI-MeSH-Surgical-Wound-Dehiscence 1965), or as defined by the trial authors). Wound dehiscence was classed as:

    • superficial (dehiscence involving skin and subcutaneous tissue); or

    • deep (dehiscence involving fascia or deeper layers, for example, burst abdomen).

  • Quality of life (short-term and long-term, as defined by the trial authors).

Secondary outcomes
  • Hypertrophic scarring at maximal follow-up.

  • Keloid scarring at maximal follow-up.

  • Incisional hernia (for abdominal surgery).

  • Hospital stay (for inpatient surgery: this will include any readmissions for wound-related complications for a period of one year, or as defined by the trial authors).

  • Impact to the patient (in terms of return to activity and return to work) and to the healthcare funder (in terms of costs related to dressings or treatment related to wound complications).

We included trials that satisfied all criteria - with the exception of outcomes - in the review, but considered these to have selective outcome reporting bias (see below).

Search methods for identification of studies

Electronic searches

In August 2013 we searched the following electronic databases to identify reports of relevant randomised clinical trials:

  • Cochrane Wounds Group Specialised Register (searched 29 August, 2013);

  • The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 7);

  • Ovid MEDLINE (1946 to August Week 3 2013);

  • Ovid MEDLINE (In-Process & Other Non-Indexed Citations August 28, 2013);

  • Ovid EMBASE (1974 to 2013 Week 34);

  • EBSCO CINAHL (1982 to 23 August 2013).

We used the following search strategy in The Cochrane Central Register of Controlled Trials (CENTRAL):

#1 MeSH descriptor Wound Closure Techniques explode all trees
#2 MeSH descriptor Sutures explode all trees
#3 (closure or close or closing or sutur*):ti,ab,kw
#4 (#1 OR #2 OR #3)
#5 MeSH descriptor Subcutaneous Tissue explode all trees
#6 (((subcutaneous or sub-cutaneous) NEAR/5 (fat or adipose or tissue*)) or "superficial fascia" or hypdermis):ti,ab,kw
#7 (#5 OR #6)
#8 (#4 AND #7)

The search strategies for Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL can be found in Appendix 2. We combined the Ovid MEDLINE search with the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity- and precision-maximising version (2008 revision) (Lefebvre 2011). We combined the EMBASE search with the Ovid EMBASE filter developed by the UK Cochrane Centre (Lefebvre 2011). We combined the CINAHL searches with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN 2010). We did not restrict studies with respect to language, date of publication or study setting.

We searched the The metaRegister of Controlled Trials (mRCT) (http://www.controlled-trials.com/mrct/) and ICTRP (International Clinical Trials Registry Platform) (http://apps.who.int/trialsearch/). The meta-register includes ISRCTN Register and NIH ClinicalTrials.gov Register as well as other registers. The ICRTP portal includes these trial registers along with trial registry data from a number of countries.

Searching other resources

We searched the reference sections of included trials to identify further relevant trials. We contacted suture manufacturers, Ethicon and Dolphin sutures, to enquire whether they were aware of any other published, unpublished or ongoing trials.

Data collection and analysis

We performed the systematic review according to instructions in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011a).

Selection of studies

Two review authors (KSG and CT) identified the trials for inclusion independently. We screened the titles and abstracts of the identified references and sought full text for references identified as potentially relevant by at least one of the review authors. Final decisions on inclusion or exclusion of studies were based on reading the full text. We have listed the excluded studies (i.e. those excluded after retrieval of the full text), with reasons for their exclusion. We resolved any differences in opinion through discussion.

Data extraction and management

Both review authors extracted the following data independently using a standardised data extraction form.

  • Year and language of publication.

  • Country of conduct of the trial.

  • Year of conduct of the trial.

  • Inclusion and exclusion criteria.

  • Sample size (total number of participants included in the trial and the number allocated to each group).

  • Details about the surgery (including location and contamination level).

  • Details of suture material and surgical technique, if the subcutaneous tissue was closed.

  • Outcomes (as described above).

  • Risk of bias (as described below).

  • Duration of follow-up.

  • Number of withdrawals (by group).

Where multiple reports exist for a trial, we planned to examine all the reports for information, but this was not necessary. We sought clarification for any unclear or missing information by contacting the authors of the individual trials. If there was any doubt about whether the trials shared the same participants - completely or partially (by identifying common authors and centres) - we planned to contact the study authors of the trials to check whether the trial report had been duplicated. We resolved any differences in opinion through discussion amongst the review authors.

Assessment of risk of bias in included studies

We followed the instructions in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011b). According to empirical evidence (Kjaergard 2001; Moher 1998; Schulz 1995; Wood 2008), the risk of bias of included trials was assessed on the basis of the following risk of bias domains.

Sequence generation
  • Low risk of bias: the method used was either adequate (e.g. computer-generated random numbers, table of random numbers), or unlikely to introduce confounding.

  • Uncertain risk of bias: there was insufficient information to assess whether the method used was likely to introduce confounding.

  • High risk of bias (the method used was improper and likely to introduce confounding (e.g. quasi-randomised studies). Such studies were excluded.

Allocation concealment
  • Low risk of bias: the method used was unlikely to induce bias on the final observed effect (e.g. central allocation).

  • Uncertain risk of bias: there was insufficient information to assess whether the method used was likely to induce bias on the estimate of effect.

  • High risk of bias: the method used was likely to induce bias on the final observed effect (e.g. open random allocation schedule).

Blinding of participants and personnel

It is impossible to blind healthcare personnel who suture (or do not suture) wounds. This is unlikely, however, to result in bias, provided that these personnel are not involved in any other aspect of patient care apart from suturing (or not suturing) the subcutaneous layer of the wound. Blinding of personnel refers to healthcare personnel involved in all other patient care apart from suturing, or not, the subcutaneous layer of the wound.

  • Low risk of bias: blinding was performed adequately, or the outcome measurement was not likely to be influenced by lack of blinding.

  • Uncertain risk of bias: there was insufficient information to assess whether the type of blinding used was likely to induce bias on the estimate of effect.

  • High risk of bias: no blinding or incomplete blinding, and the outcome or the outcome measurement was likely to be influenced by lack of blinding.

Blinding of outcome assessors
  • Low risk of bias: blinding was performed adequately, or the outcome measurement was not likely to be influenced by lack of blinding.

  • Uncertain risk of bias: there was insufficient information to assess whether the type of blinding used was likely to induce bias on the estimate of effect.

  • High risk of bias: no blinding or incomplete blinding, and the outcome or the outcome measurement was likely to be influenced by lack of blinding.

Incomplete outcome data
  • Low risk of bias: if there was no missing data, or if the underlying reasons for missing data were unlikely to make treatment effects depart from plausible values, or the proportion of missing information compared to complete information was too small to make a clinically significant difference in the treatment effect, or proper methods have been employed to handle missing data.

  • Uncertain risk of bias: there was insufficient information to assess whether, when the missing data were combined using a method to handle missing data, it was likely to induce bias on the estimate of effect.

  • High risk of bias: the crude estimate of effects clearly will be biased due to the underlying reasons for missing data, or the proportion of missing information compared to complete information is large enough to make a clinically significant difference in the treatment effect, and the methods used to handle missing data were unsatisfactory (e.g. complete case estimate).

Selective outcome reporting
  • Low risk of bias: the trial protocol was available and all of the pre-specified outcomes in the trial protocol that were of interest in the review have been reported; if the trial protocol was not available, all the primary outcomes in this review were reported.

  • Uncertain risk of bias: there was insufficient information to assess whether the magnitude and direction of the observed effect was related to selective outcome reporting.

  • High risk of bias: not all of the pre-specified outcomes in the trial protocol that were of interest in the review have been reported; if the trial protocol was not available, all the primary outcomes in this review have not been reported.

We considered trials classified as being at low risk of bias in all the above domains to be 'low risk of bias trials'. We considered the other trials to be 'high risk of bias trials'.

Measures of treatment effect

For dichotomous variables, we calculated the risk ratio (RR) with 95% confidence intervals (CI). For continuous variables that can be quantified on a common scale, such as hospital stay, we calculated the mean difference (MD) with 95% CI; for continuous variables where different assessment scales might be used, such as quality of life, we planned to calculate the standardised mean difference (SMD) with 95% CI.

Unit of analysis issues

The unit of analysis was the surgical wound subject to the method of closure being investigated. While we accepted the results from trials in which multiple incisions were randomised to different groups, we did not accept trials in which part of the surgical incision was randomised to one group and the remaining part to the other group. If multiple incisions were randomised to different groups, we included the trial only if appropriate analysis was undertaken by taking the within-subject correlation (clustering) into account, or, if it was possible to perform such an analysis from the available data.

Dealing with missing data

We performed an intention-to-treat analysis whenever possible (Newell 1992). We planned to impute missing data for binary outcomes using various scenarios such as best-best, best-worst, worst-best, worst-worst scenarios (Gurusamy 2009). In the best-best scenario, the outcomes of people with missing data in both groups were assumed to be good. In the best-worst scenario, the outcomes for people with missing data in the intervention group were assumed to be good, and assumed to be bad for those with missing data in the control group. The worst-best scenario is the opposite of the best-worst scenario, with the outcomes for people with missing data in the intervention group assumed to be bad, and assumed to be good for people with missing data in the control group. In the worst-worst scenario, the outcomes for people with missing data in both groups were assumed to be bad.

For continuous outcomes, we used available-case analysis. We imputed the standard deviation from P values according to instructions in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011c), and we used the median for the meta-analysis when the mean was not available. If it was not possible to calculate the standard deviation from the P value or the confidence intervals, we imputed the standard deviation as the highest standard deviation in the other trials included under that outcome, fully recognising that this form of imputation would decrease the weight of the study for calculation of mean differences and bias the effect estimate to no effect in case of standardised mean difference (Higgins 2011d).

Assessment of heterogeneity

We explored heterogeneity by the Chi2 test, with significance set at P value 0.10, and measured the quantity of heterogeneity by I2 (Higgins 2002).

Thresholds for the interpretation of I2 can be misleading. A rough guide to interpretation follows (Deeks 2011):

  • 0 to 40%: might not be important;

  • 30% to 60%: may represent moderate heterogeneity;

  • 50% to 90%: may represent substantial heterogeneity;

  • 75% to 100%: represents considerable heterogeneity.

The measure of heterogeneity was used to grade the level of evidence for the 'Summary of findings' table (Schünemann 2011).

Assessment of reporting biases

Had we included 10 or more trials, we planned to explore reporting bias using visual asymmetry on the funnel plot (Egger 1997; Macaskill 2001). We planned to perform linear regression, as described by Egger 1997, to determine funnel plot asymmetry.

Data synthesis

We performed the meta-analysis using Review Manager 5 software (RevMan 2011), and following the recommendations of The Cochrane Collaboration (Deeks 2011). We used both a random-effects model (DerSimonian 1986), and a fixed-effect model (DeMets 1987), for meta-analyses. In case of discrepancy between the two models, identified from the pooled estimates and their CIs (which results in an alteration in the interpretation of information), we planned to report both results; otherwise we have reported the results of the fixed-effect model. With regard to dichotomous outcomes: risk ratio (RR) calculations do not include trials in which no events occurred in either group in the meta-analysis, whereas risk difference calculations do. We planned to report the risk difference (RD) if the results using this association measure were different from risk ratio in terms of statistical significance. Risk ratio, however, was the measure that we used to arrive at conclusions, since risk ratios perform better when there are differences in the control event rate (proportion of participants who develop the event in the control group). We used an inverse variance approach for the continuous outcomes.

Summary of findings

We have presented all the primary and secondary outcomes for which data were available in a 'Summary of findings' table (Schünemann 2011). The quality of evidence was based on various parameters, namely: risk of bias, inconsistency, indirectness, imprecision, and reporting bias, and based on the recommendations of the GRADE Working Group (Schünemann 2011).

Subgroup analysis and investigation of heterogeneity

We planned to perform the following subgroup analyses.

  • Different types of suture material.

  • Different types of operations (trunk versus limb surgeries).

  • Classification of wounds (clean, clean contaminated, contaminated, dirty or infected wounds) (Garner 1986).

  • Trials with adult participants compared to trials with child participants.

We planned to use a P value of less than 0.05 for the Chi2 test for subgroup differences in order to identify the differences between subgroups.

Sensitivity analysis

We planned to perform sensitivity analysis by imputing data for dichotomous outcomes using various scenarios, including best-best scenario, worst-worst scenario, best-worst scenario, and worst-best scenario (Gurusamy 2009). We also planned to perform sensitivity analysis by excluding the trials at high risk of bias, and performed a sensitivity analysis by excluding trials in which the mean and the standard deviation were imputed.

Results

Description of studies

Results of the search

We identified a total of 172 unique references through electronic searches. We excluded 158 clearly irrelevant references through reading titles and abstracts. We sought 14 references in full text for further assessment. We did not identify any additional references to trials by scanning reference lists of included trials. We identified an ongoing trial by searching the trial registry (ChiCTR-TRC-11001152). We excluded six references because of the reasons mentioned in the Characteristics of excluded studies and Excluded studies. One other reference had two trials, the first of which we included, and the second of which we excluded (el Gamel 1994; el Gamel 1994a). Eight trials (eight citations) met the inclusion criteria and were included in this review (Cardosi 2006; el Gamel 1994; Hussain 1990; Kong 1993; Kore 2000; Paral 2007; Tamelis 2005; Tiryakioglu 2010). The reference flow is shown in Figure 1.

Figure 1.

Study flow diagram

Included studies

A total of eight references describing eight trials were included in this review (Cardosi 2006; el Gamel 1994; Hussain 1990; Kong 1993; Kore 2000; Paral 2007; Tamelis 2005; Tiryakioglu 2010). Six references described six two-armed trials (Hussain 1990; Kong 1993; Kore 2000; Paral 2007; Tamelis 2005; Tiryakioglu 2010). One reference described a three-armed parallel randomised controlled trial (Cardosi 2006), but only two of the arms in this trial were eligible for inclusion in this review. One reference described two trials (el Gamel 1994; el Gamel 1994a). As mentioned earlier, only one of the trials was included in this review (el Gamel 1994). In total, 1318 participants were randomised in the eight trials included in the review. Two trials (recruiting 491 participants) did not contribute any data for this review, either because they did not report any of the outcomes included in the review, or because these outcomes were not reported adequately (Kong 1993; Paral 2007). Therefore, 827 participants were randomised in the six trials contributing data to the review, of which 12 withdrew post-randomisation, leaving a total of 815 participants. Of these, 410 were randomised to subcutaneous closure and 405 to no subcutaneous closure (Cardosi 2006; el Gamel 1994; Hussain 1990; Kore 2000; Tamelis 2005; Tiryakioglu 2010).

Two trials included people undergoing gynaecological operations that required skin closure (Cardosi 2006; Kore 2000). Two trials included people undergoing saphenous venous graft excisions (el Gamel 1994; Tiryakioglu 2010). One trial included people undergoing elective open cholecystectomy operations (removal of gallbladder) (Hussain 1990). One trial included people who underwent colorectal operations that might have been contaminated or dirty (Tamelis 2005). All operations in the remaining trials were performed in the elective setting, and were either clean or clean-contaminated. Continuous sutures were used for suturing the subcutaneous tissue in three trials (Cardosi 2006; Kore 2000; Tiryakioglu 2010); interrupted sutures were used for suturing the subcutaneous tissue in one trial (Hussain 1990; Kong 1993; Paral 2007); and the method of subcutaneous tissue closure was not reported in two trials (el Gamel 1994; Tamelis 2005). Participants were followed for a period of one week to two months after surgery (Characteristics of included studies). Four trials followed up participants for more than 30 days (Cardosi 2006; el Gamel 1994; Kong 1993; Tiryakioglu 2010); while the remaining four trials followed the participants for 30 days or less (Hussain 1990; Kore 2000; Paral 2007; Tamelis 2005).

Excluded studies

A total of seven full-text articles were excluded. One study was a quasi-randomised study (Milewski 1980). One study was not a comparison of subcutaneous versus no subcutaneous closure (Deliaert 2009). In two studies, a single-layer method of wound closure was compared with a two-layered method of wound closure. However, it was not clear whether the subcutaneous fat was included in the single-layer closure method (Nouraei 2010; Singer 2005). In two studies, it was not clear whether the skin closure was performed using the same method in the two groups (Stenvik 2006; Teebken 2000). In one trial, participants had bilateral operations (vein excision from the legs), then one wound was randomised to subcutaneous closure and the other to no subcutaneous closure (el Gamel 1994a). The trial analysis did not take intra-participant correlation into account, and the trial report did not provide details that allowed us to take the intra-participant correlation into account during meta-analysis (el Gamel 1994a).

Risk of bias in included studies

All the trials were at high risk of bias as shown in Figure 2 and Figure 3.

Figure 2.

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies

Figure 3.

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

Allocation

Two trials were free from selection bias (Paral 2007; Tamelis 2005).  These trial had low risk of bias in random sequence generation and allocation concealment. The remaining trials had unclear risks of bias.

Blinding

One trial reported that participants and outcome assessors were blinded (Tamelis 2005). However, the surgeons were aware of group allocation prior to surgery, and so this trial was classified as being at high risk of bias due to lack of blinding of healthcare providers, but at low risk of bias due to lack of blinding of outcome assessors (Tamelis 2005). None of the remaining trials reported whether blinding of participants, healthcare providers involved in management of participants, or outcome assessors was done.

Incomplete outcome data

The participant flow was available in three trials (Paral 2007; Tamelis 2005; Tiryakioglu 2010); there were post-randomisation drop-outs in these trials, and in one trial, the post-randomisation drop-outs were significant (5.9% of randomised participants) (Paral 2007). Since none of the outcomes of interest for this review was reported in this trial, it was not possible to assess the impact this had, but it is likely that the treatment effects would have been modified because of these post-randomisation drop-outs. So, this trial was classified as being at high risk of bias (Paral 2007). In another trial, fewer than 5% of participants were excluded after randomisation (Tiryakioglu 2010), however, information concerning the group(s) to which these participants belonged was not available, and we were unable to assess the impact of these post-randomisation drop-outs on the treatment effect. This trial was classified as being at unclear risk of bias (Tiryakioglu 2010). In the third trial, the post-randomisation drop-outs did not make a clinically significant difference to the treatment effects when the outcomes were imputed under different scenarios (Tamelis 2005) (Analysis 1.5), so this trial was considered to be at low risk of attrition bias (Tamelis 2005). The participant flow was not reported adequately for the remaining trials, so it was not possible to determine whether they had any post-randomisation drop-outs, or to assess their risk of bias due to incomplete outcome data.

Selective reporting

Trial protocols were not available for any of the trials, and none of the included studies reported all the primary outcomes of this review. So, all eight trials were considered to be at high risk of bias for selective outcome reporting.

Other potential sources of bias

We did not look for any other sources of bias in the trials.

Effects of interventions

See: Summary of findings for the main comparison Subcutaneous closure compared to no subcutaneous closure for non-caesarean surgery

Six trials randomised a total of 815 participants to either subcutaneous closure (410 participants) or no subcutaneous closure (405 participants) (Cardosi 2006; el Gamel 1994; Hussain 1990; Kore 2000; Tamelis 2005; Tiryakioglu 2010). The only outcomes reported were superficial SSI, superficial and deep wound dehiscence, and length of hospital stay. The remaining outcomes of interest in the review, deep SSI, organ space infection, quality of life, hypertrophic scarring, keloid scarring, incisional hernia and impact to the patient and to the healthcare funder, were not reported in any of the trials.

The results are summarised in Summary of findings for the main comparison.

Superficial surgical site infection (SSI)

Six trials reported superficial SSI (Cardosi 2006; el Gamel 1994; Hussain 1990; Kore 2000; Tamelis 2005; Tiryakioglu 2010). The trials were pooled using a fixed-effect model.There was no significant difference in the proportion of participants with superficial SSI between the two groups (RR 0.84; 95% CI 0.53 to 1.33; I2 = 0%) (Analysis 1.1). There was no change to the conclusions when the random-effects model was used, or when the risk difference was calculated.

Superficial wound dehiscence

Two trials reported superficial wound dehiscence (Cardosi 2006; Kore 2000). The trials were pooled using a fixed-effect model. There was no significant difference in the proportion of participants with superficial wound dehiscence between the two groups (RR 0.56; 95% CI 0.22 to 1.41; I2 = 0%) (Analysis 1.2). There was no change to the conclusions when the random-effects model was used, or when the risk difference was calculated.

Deep wound dehiscence

One trial reported deep wound dehiscence (Kore 2000). The authors reported this as deep wound disruption and complete wound dehiscence (Kore 2000). There was no significant difference in the proportion of participants with deep wound dehiscence between the two groups (RR 0.25; 95% CI 0.03 to 2.11) (Analysis 1.3). Since only one trial reported this outcome, the issue of fixed-effect model versus random-effects model did not arise. There was no change in the conclusions when risk difference was used as the effect measure.

Hospital stay

Three trials reported on length of hospital stay (Cardosi 2006; Hussain 1990; Tiryakioglu 2010). There was no significant difference in the length of hospital stay between the two groups (MD 0.10 days; 95% CI -0.45 to 0.64; I2 = 75%) (Analysis 1.4). There was no change to the results when the random-effects model was used.

Subgroup analysis

We did not perform any subgroup analysis because too few trials were included in this review.

Sensitivity analysis

Only two of the trials that contributed data to this review had post-randomisation drop-outs mentioned (Tamelis 2005; Tiryakioglu 2010). One trial did not report the number of post-randomisation drop-outs from each group individually (Tiryakioglu 2010), so we were unable to perform the planned sensitivity analysis for this trial where we planned to impute missing data according to different scenarios (Tiryakioglu 2010). One trial provided information on the number of post-randomisation drop-outs in each group (Tamelis 2005); imputing data according to the different scenarios did not alter the results (Analysis 1.5). All trials were at high risk of bias, and, therefore, we could not perform a sensitivity analysis in which we excluded trials at high risk of bias.

Excluding trials in which either mean or standard deviation were imputed did not alter the conclusions for hospital stay (Cardosi 2006; Hussain 1990), which was the only continuous outcome (Analysis 1.6). The above were a priori sensitivity analyses. We also performed a post hoc sensitivity analysis excluding trials that followed participants for less than 30 days (Hussain 1990; Kore 2000; Tamelis 2005). This applied to two outcomes, namely, superficial SSI and superficial wound dehiscence. This sensitivity analysis did not alter the conclusions (Analysis 1.7; Analysis 1.8).

Reporting bias

We did not explore reporting bias by funnel plot because we included fewer than 10 trials in this review.

Discussion

Summary of main results

In this review, we compared the outcomes in non-caesarean surgical procedures where there was subcutaneous closure or no subcutaneous closure of wounds. A total of 815 participants were randomised to subcutaneous closure (410 participants) or no subcutaneous closure (405 participants) in six trials that provided data for this review (Cardosi 2006; el Gamel 1994; Hussain 1990; Kore 2000; Tamelis 2005; Tiryakioglu 2010). In these six trials, 7.7% of participants (63/815 of participants) developed superficial surgical site infection (SSI); there was no significant difference between the two groups. There was insufficient information to determine whether the overall proportion of participants who developed SSI differed between different classes of wounds such as clean or clean-contaminated wounds. Two trials reported superficial wound dehiscence (Cardosi 2006; Kore 2000); overall, 7.9% (17/215) of participants developed superficial wound dehiscence. The other trials did not report this outcome, but it is not clear whether this was because the problem did not arise, or because superficial wound dehiscence was not measured. There was no significant difference between closure groups for superficial wound dehiscence in the trials that reported this outcome. Only one trial reported deep wound dehiscence (Kore 2000); in this trial 8.3% (5/60) participants developed the problem. The trial authors reported deep wound dehiscence as 'deep wound disruption' (disruption of the wound by more than 1 cm depth) and complete wound dehiscence (Kore 2000). There is no standard definition for deep wound dehiscence, and the definition used by the authors may be one of the reasons for the high incidence of deep wound dehiscence reported in this trial (Kore 2000), i.e., some wound dehiscences considered to be superficial in some trials may have been considered as deep wound dehiscence in this trial. Lack of standard definition for some wound complications can make it difficult to compare different interventions and is an area that needs urgent attention.There was no significant difference in the length of hospital stay between the groups, though it is not known whether this is due to a lack of effect or a lack of evidence of effect. The confidence intervals for these outcomes were wide, and significant benefits or harms of subcutaneous closure cannot be ruled out.

It should be noted that participants were followed for a period of at least 30 days in only three of the trials that provided data for this review (Cardosi 2006; el Gamel 1994; Tiryakioglu 2010). It is possible that the true proportion of participants who developed complications would have been higher in the remaining three trials, had the participants been followed up for the same length of time (Hussain 1990; Kore 2000; Tamelis 2005). A sensitivity analysis excluding the trials with follow-ups shorter than 30 days did not alter the conclusions. It is also noteworthy that none of the trials assessed the impact of subcutaneous closure on quality of life, long-term patient outcomes (the follow-up period in the trials varied between one week and two months after surgery), or financial implications to the healthcare funder. Since closure of subcutaneous tissue is an additional step in surgery, it will increase operating time to an extent dependent on the length of the incision. Subcutaneous closure also incurs use of additional suture material. Whether this increase in costs, due to increase in operating time and use of suture materials, is compensated for by a decrease in wound complications, a subsequent reduction in management costs, and an increase in quality of life is not known. Given that mortality is unlikely to be affected by the use (or non-use) of subcutaneous closure, quality of life and costs will be the main factors that will determine which intervention is recommended by healthcare funders.

Overall completeness and applicability of evidence

It is worth noting that most participants in this review had clean or clean-contaminated operations (Garner 1986). Hence, the review's findings are mainly applicable to that population. Two trials included people with at least 2.5 cm to 3 cm of subcutaneous fat (Cardosi 2006; Kore 2000). There were no such restrictions in the remaining four trials (el Gamel 1994; Hussain 1990; Tamelis 2005; Tiryakioglu 2010). The effect estimate appeared consistent across all the studies for wound complications. So, this review is applicable to all participants irrespective of the thickness of their fat.

Quality of the evidence

The overall quality of evidence is very low as shown in Summary of findings for the main comparison. In particular, the risk of bias in the trials was high, and the lack of blinding is a major concern, so it is possible that the observed effect may not be the true effect.

Potential biases in the review process

We have performed a thorough search of the literature without any restrictions concerning language or date of publication. Despite doing this, we were not able to identify any trials conducted - but not reported - in the pre-mandatory trial registration era. We included only trials in which it was clear that the comparison involved subcutaneous versus no subcutaneous sutures, without any differences in the other aspects of wound closure. As mentioned in the Excluded studies sections, four studies were excluded because it was not clear whether they met the inclusion criteria for this review (Nouraei 2010; Singer 2005; Stenvik 2006; Teebken 2000). While the majority of those four studies are unlikely to be included in this review, some may have met the inclusion criteria for the review but did not report the essential information with sufficient clarity to be included. Most of these trials were old, and even the more recent publications did not provide information about the impact on long-term patient outcomes or implications for healthcare funders.

Agreements and disagreements with other studies or reviews

This is the first systematic review on this topic. While the authors of some of the trials included in this review recommended either subcutaneous closure (Hussain 1990; Kore 2000), or no subcutaneous closure (el Gamel 1994; Tiryakioglu 2010), based on their observations, we do not make either of these recommendations because of a lack of evidence to support either position.

Authors' conclusions

Implications for practice

There is currently evidence of very low quality which is insufficient to support or refute subcutaneous closure after non-caesarean operations.

Implications for research

The use of subcutaneous closure has the potential to affect patient outcomes as well as utilisation of healthcare resources in terms of costs related to dressings and treatment related to wound complications. Further well-designed trials, at low risk of bias, are necessary to compare subcutaneous closure with no subcutaneous closure in all types of surgery. Outcomes should include long-term outcomes, such as quality of life, hypertrophic or keloid scarring, and hernia (in abdominal operations), in addition to short-term outcomes, such as wound complications, short-term quality of life and short-term resource utilisation.

Acknowledgements

The authors would like to acknowledge the contribution of the Wounds Group editor (Julie Bruce), peer referees (Susanne Hempel; Robert Wyllie; Christine Fyfe), Statistical editor (Elmer Villanueva), and copy editor Elizabeth Royle, for their role in improving the review. To Ms Tina Sedaghati, who helped with the translation of Nouraei 2010.

Data and analyses

Download statistical data

Comparison 1. Subcutaneous closure versus no subcutaneous closure
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Superficial surgical site infection6815Risk Ratio (M-H, Fixed, 95% CI)0.84 [0.53, 1.33]
2 Superficial wound dehiscence2215Risk Ratio (M-H, Fixed, 95% CI)0.56 [0.22, 1.41]
3 Deep wound dehiscence160Risk Ratio (M-H, Fixed, 95% CI)0.25 [0.03, 2.11]
4 Hospital stay3434Mean Difference (IV, Fixed, 95% CI)0.10 [-0.45, 0.64]
5 Superficial surgical site infection (sensitivity analysis - missing data imputation)6 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
5.1 Best-best analysis6824Risk Ratio (M-H, Fixed, 95% CI)0.83 [0.52, 1.32]
5.2 Best-worst analysis6824Risk Ratio (M-H, Fixed, 95% CI)0.74 [0.47, 1.16]
5.3 Worst-best analysis6824Risk Ratio (M-H, Fixed, 95% CI)0.97 [0.63, 1.52]
5.4 Worst-worst analysis6824Risk Ratio (M-H, Fixed, 95% CI)0.87 [0.57, 1.33]
6 Hospital stay (sensitivity analysis)1 Mean Difference (IV, Fixed, 95% CI)Totals not selected
7 Superficial surgical site infection (sensitivity analysis - > 30 days)3434Risk Ratio (M-H, Fixed, 95% CI)0.54 [0.25, 1.19]
8 Superficial wound dehiscence (sensitivity analysis - > 30 days)1 Risk Ratio (M-H, Fixed, 95% CI)Totals not selected
Analysis 1.1.

Comparison 1 Subcutaneous closure versus no subcutaneous closure, Outcome 1 Superficial surgical site infection.

Analysis 1.2.

Comparison 1 Subcutaneous closure versus no subcutaneous closure, Outcome 2 Superficial wound dehiscence.

Analysis 1.3.

Comparison 1 Subcutaneous closure versus no subcutaneous closure, Outcome 3 Deep wound dehiscence.

Analysis 1.4.

Comparison 1 Subcutaneous closure versus no subcutaneous closure, Outcome 4 Hospital stay.

Analysis 1.5.

Comparison 1 Subcutaneous closure versus no subcutaneous closure, Outcome 5 Superficial surgical site infection (sensitivity analysis - missing data imputation).

Analysis 1.6.

Comparison 1 Subcutaneous closure versus no subcutaneous closure, Outcome 6 Hospital stay (sensitivity analysis).

Analysis 1.7.

Comparison 1 Subcutaneous closure versus no subcutaneous closure, Outcome 7 Superficial surgical site infection (sensitivity analysis - > 30 days).

Analysis 1.8.

Comparison 1 Subcutaneous closure versus no subcutaneous closure, Outcome 8 Superficial wound dehiscence (sensitivity analysis - > 30 days).

Appendices

Appendix 1. Classification of surgical wounds

Clean wound

  • Uninfected operative wounds

  • No inflammation is encountered

  • Respiratory, alimentary, genital or uninfected urinary tracts are not entered

  • Primarily closed

Clean-contaminated wound

  • Respiratory, alimentary, genital or urinary tract is entered under controlled conditions

  • Without unusual contamination

  • No evidence of infection or major break in sterile technique is encountered

Contaminated wound

  • Open, fresh accidental wounds or operations with major breaks in sterile technique or gross spillage from the gastrointestinal tract or incisions in which acute, non-purulent inflammation is encountered

Dirty wound

  • Old traumatic wounds with retained devitalised tissue or those that involve existing clinical infection or perforated viscera (i.e. the organisms causing postoperative infection were present in the operative field before the operation)

Appendix 2. Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL Search Strategies

Ovid Medline

1 exp Wound Closure Techniques/ (38162)
2 exp Sutures/ (12060)
3 (closure or close or closing or sutur*).tw. (300829)
4 or/1-3 (324065)
5 exp Subcutaneous Tissue/ (1703)
6 (((subcutaneous or sub-cutaneous) adj5 (fat or adipose or tissue*)) or superficial fascia or hypdermis).tw. (18170)
7 or/5-6 (19321)
8 4 and 7 (937)
9 randomized controlled trial.pt. (338195)
10 controlled clinical trial.pt. (85043)
11 randomized.ab. (241810)
12 placebo.ab. (134534)
13 clinical trials as topic.sh. (162087)
14 randomly.ab. (173722)
15 trial.ti. (103477)
16 or/9-15 (782338)
17 (animals not (humans and animals)).sh. (3663525)
18 16 not 17 (720068)
19 8 and 18 (66)

Ovid Embase

1 exp wound closure/ (8769)
2 exp suture/ (28180)
3 (closure or close or closing or sutur*).tw. (400571)
4 or/1-3 (412703)
5 exp subcutaneous tissue/ (22275)
6 (((subcutaneous or sub-cutaneous) adj5 (fat or adipose or tissue*)) or superficial fascia or hypdermis).tw. (25061)
7 or/5-6 (37394)
8 4 and 7 (1710)
9 Randomized controlled trials/ (26220)
10 Single-Blind Method/ (16988)
11 Double-Blind Method/ (115513)
12 Crossover Procedure/ (36187)
13 (random$ or factorial$ or crossover$ or cross over$ or cross-over$ or placebo$ or assign$ or allocat$ or volunteer$).ti,ab. (1213080)
14 (doubl$ adj blind$).ti,ab. (140490)
15 (singl$ adj blind$).ti,ab. (13290)
16 or/9-15 (1268250)
17 exp animals/ or exp invertebrate/ or animal experiment/ or animal model/ or animal tissue/ or animal cell/ or nonhuman/ (19613926)
18 human/ or human cell/ (14178567)
19 and/17-18 (14131914)
20 17 not 19 (5482012)
21 16 not 20 (1091425)
22 8 and 21 (133)

EBSCO CINAHL

S22 S9 AND S21
S21 S10 or S11 or S12 or S13 or S14 or S15 or S16 or S17 or S18 or S19 or S20
S20 MH "Quantitative Studies"
S19 TI placebo* or AB placebo*
S18 MH "Placebos"
S17 TI random* allocat* or AB random* allocat*
S16 MH "Random Assignment"
S15 TI randomi?ed control* trial* or AB randomi?ed control* trial*
S14 AB ( singl* or doubl* or trebl* or tripl* ) and AB ( blind* or mask* )
S13 TI ( singl* or doubl* or trebl* or tripl* ) and TI ( blind* or mask* )
S12 TI clinic* N1 trial* or AB clinic* N1 trial*
S11 PT Clinical trial
S10 MH "Clinical Trials+"
S9 S4 AND S8
S8 S5 OR S6 OR S7
S7 TI ( "superficial fascia" or hypdermis ) OR AB ( "superficial fascia" or hypdermis )
S6 TI ( (subcutaneous or sub-cutaneous) N5 (fat or adipose or tissue*) ) OR AB ((subcutaneous or sub-cutaneous) N5 (fat or adipose or tissue*) )
S5 (MH "Abdominal Fat")
S4 S1 OR S2 OR S3
S3 TI ( closure or close or closing or sutur* ) OR AB ( closure or close or closing or sutur* )
S2 (MH "Suture Techniques")
S1 (MH "Sutures")

Contributions of authors

KS Gurusamy conceived the review question; developed and co-ordinated the review; secured funding; completed the first draft of the review; advised on, wrote, edited and made an intellectual contribution to the review; approved the final version prior to submission, and is its guarantor.
Clare Toon extracted data, made an intellectual contribution to the review and approved the final version prior to submission.
Brian Davidson conceived the review question; secured funding; made an intellectual contribution; advised on part of the review and approved the final version prior to submission.

Contributions of editorial base

Nicky Cullum: edited the review; advised on methodology, interpretation and review content.
Susan O'Meara: Editor; approved the final review prior to submission.
Sally Bell-Syer: co-ordinated the editorial process; advised on methodology, interpretation and content; and edited the review.
Ruth Foxlee: designed the search strategy and edited the search methods section.
Rachel Richardson: edited the review.

Declarations of interest

This project was funded by the National Institute for Health Research (NIHR).

Disclaimer

Department of Health disclaimer: The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the NIHR, NHS (National Health Service), or the Department of Health.

KS Gurusamy: no known conflict of interest
Clare Toon: no known conflict of interest
Brian Davidson: no known conflict of interest

Sources of support

Internal sources

  • No sources of support supplied

External sources

  • National Institute for Health Research, UK.

    National Institute for Health Research, the health research wing of the UK Government Department of Health funds K Gurusamy to complete this review.

  • The National Institute for Health Research (NIHR) is the sole funder of the Cochrane Wounds Review Group, UK.

Differences between protocol and review

A new outcome "Impact to the patient (in terms of return to activity and return to work) and to the healthcare funder (in terms of costs related to dressings or treatment related to wound complications)" was added, as this outcome will permit assessment of the impact of any difference in incidence of wound complications for both participants and healthcare funders.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Cardosi 2006

MethodsRandomised clinical trial
ParticipantsCountry: USA
Number randomised: 155
Post-randomisation drop-outs: not stated
Revised sample size: 155
Average age: 57 years
Females: 155 (100%)
Inclusion criteria: women having elective gynaecological pelvic surgery through a vertical midline incision with a subcutaneous thickness of 3 cm or more
Exclusion criteria: women unable to provide informed consent; hospitalised > 24 h preoperatively; having laparotomy after unsuccessful laparoscopy or vaginal surgery
Interventions

Participants randomly assigned to 2 groups
Group 1 (n = 78): subcutaneous closure
Group 2 (n = 77): no subcutaneous closure

We excluded a third group (n = 67) who were randomised to subcutaneous drain

Details of surgery including location and contamination: pelvic surgery for various benign and malignant conditions (clean and clean-contaminated)
Details of suture material: polyglactin 2-0
Continuous or interrupted closure of subcutaneous tissue: continuous

Follow-up: 6 weeks after surgery

OutcomesWound complications and hospital stay
Notes

We attempted to contact the trial authors in February 2013

Source of funding: not stated

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskComment: this information was not available
Allocation concealment (selection bias)Unclear riskComment: this information was not available
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: this information was not available
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: this information was not available
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskComment: this was a 3-armed trial, 2 arms of which were eligible for inclusion in this review. There were 3 post-randomisation drop-outs: 1 participant received 48 h of preoperative antibiotics for a pelvic abscess; 1 had postoperative fascial dehiscence requiring reoperation; and 1 had to return to the operating room to control pelvic bleeding. The groups to which these post-randomisation drop-outs belonged were not reported. All three participants could have belonged to the excluded group or all the three participants could have belonged to the two included groups. Since this information was not clear, we have classified this as unclear
Selective reporting (reporting bias)High riskComment: the trial protocol was not available and the trial did not report all the primary outcomes of this review

el Gamel 1994

MethodsRandomised clinical trial
ParticipantsCountry: UK, USA
Number randomised: 200
Post-randomisation drop-outs: not stated
Revised sample size: 200
Average age: not stated
Male: female ratio: 140 (70%): 60 (30%)
Inclusion criteria: people requiring saphenous vein graft excision for coronary artery bypass graft (only people in whom the excision was performed in the thighs were included in this review since the people requiring saphenous vein graft excision from the legs were randomised separately in a different trial which was excluded (el Gamel 1994a)
Interventions

Participants randomly assigned to 2 groups

Group 1 (n = 100): subcutaneous closure
Group 2 (n = 100): no subcutaneous closure

Details of surgery including location and contamination: saphenous vein graft excision (clean)
Details of suture material: Vicryl 2-0
Continuous or interrupted closure of subcutaneous tissue: not stated

Follow-up: 4-6 weeks after surgery (outpatient review)

OutcomesWound infection
Notes

We attempted to contact the trial authors in February 2013

Source of funding: not stated

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskComment: this information was not available
Allocation concealment (selection bias)Unclear riskComment: this information was not available
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: this information was not available
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: this information was not available
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskComment: this information was not available
Selective reporting (reporting bias)High riskComment: the trial protocol was not available and the trial did not report all the primary outcomes of this review

Hussain 1990

MethodsRandomised clinical trial
ParticipantsCountry: Saudi Arabia
Number randomised: 200
Post-randomisation drop-outs: not stated
Revised sample size: 200
Average age: 37 years
Male: female ratio: 30 (15%): 170 (85%)
Inclusion criteria: people having open cholecystectomy for chronic cholecystitis
Exclusion criteria: chronic obstructive airway disease; people requiring choledochotomy (incision on the common bile duct)
Interventions

Participants randomly assigned to 2 groups
Group 1 (n = 100): subcutaneous closure
Group 2 (n = 100): no subcutaneous closure

Details of surgery including location and contamination: cholecystectomy for chronic cholecystitis (clean-contaminated)
Details of suture material: polyglactin 2
Continuous or interrupted closure of subcutaneous tissue: interrupted

Follow-up: until hospital discharge

OutcomesWound infection and hospital stay
Notes

We attempted to contact the trial authors in February 2013

Source of funding: not stated

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskComment: this information was not available
Allocation concealment (selection bias)Unclear riskQuote: " . . . randomized by sealed envelopes into two groups"
Comment: further details were not available
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: this information was not available
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: this information was not available
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskComment: this information was not available
Selective reporting (reporting bias)High riskComment: the trial protocol was not available and the trial did not report all the primary outcomes of this review

Kong 1993

MethodsRandomised clinical trial
ParticipantsCountry: UK
Number randomised: 50
Post-randomisation drop-outs: not stated
Revised sample size: 50
Average age: 72 years
Male: female ratio: 11 (22%): 39 (78%)
Inclusion criteria: people having hip operation (hemiarthroplasty or hip replacement)
Exclusion criteria: people with previous surgery to the same side
Interventions

Participants randomly assigned to 2 groups
Group 1 (n = 25): subcutaneous closure
Group 2 (n = 25): no subcutaneous closure

Details of surgery including location and contamination: hip operations (clean)
Details of suture material: Vicryl (thickness not stated)
Continuous or interrupted closure of subcutaneous tissue: interrupted

Follow-up: 8 days after surgery

OutcomesThis trial reported none of the outcomes of interest for this review
Notes

We attempted to contact the trial authors in February 2013

Source of funding: not stated

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskComment: this information was not available
Allocation concealment (selection bias)Unclear riskComment: this information was not available
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: this information was not available
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: this information was not available
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskComment: this information was not available
Selective reporting (reporting bias)High riskComment: the trial protocol was not available, and this trial reported none of the primary outcomes of this review

Kore 2000

MethodsRandomised clinical trial
ParticipantsCountry: India
Number randomised: 60
Post-randomisation drop-outs: not stated
Revised sample size: 60
Average age: 45 years
Females: 60 (100%)
Inclusion criteria: women undergoing abdominal hysterectomy with at least 2.5 cm of subcutaneous fat
Interventions

Participants randomly assigned to 2 groups
Group 1 (n = 30): subcutaneous closure
Group 2 (n = 30): no subcutaneous closure

Details of surgery including location and contamination: abdominal hysterectomy (clean)
Details of suture material: polyglycolic acid 2-0
Continuous or interrupted closure of subcutaneous tissue: continuous

Follow-up: 7 days after surgery

OutcomesWound complications
Notes

We attempted to contact the trial authors in February 2013

Source of funding: not stated

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskComment: this information was not available
Allocation concealment (selection bias)Unclear riskComment: this information was not available
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: this information was not available
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: this information was not available
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskComment: this information was not available
Selective reporting (reporting bias)High riskComment: the trial protocol was not available and the trial did not report all the primary outcomes of this review

Paral 2007

MethodsRandomised clinical trial
ParticipantsCountry: Czech Republic
Number randomised: 441
Post-randomisation drop-outs: 26 (5.9%)
Revised sample size: 415
Average age: 55 years
Male: female ratio: 274 (66%): 141 (34%)
Inclusion criteria: people requiring elective abdominal surgery
Interventions

Participants randomly assigned to 2 groups
Group 1 (n = 210): subcutaneous closure
Group 2 (n = 205): no subcutaneous closure

Details of surgery including location and contamination: elective abdominal surgery (clean and clean-contaminated)

Details of suture material: polyglactin 2-0
Continuous or interrupted closure of subcutaneous tissue: interrupted

Follow-up: 30 days after surgery

OutcomesWound infection: the number of participants who developed wound infection within 30 days was not reported - instead the authors presented the participants who had wound infection on different post-operative days
Notes

We attempted to contact the authors in February 2013
Reasons for post-randomisation drop-outs:

Clean wounds: did not receive intervention (3 in each group) and lost to follow-up (6 in intervention group, 5 in control group)

Clean contaminated wounds: did not receive intervention (1 in intervention group, 4 in control group) and lost to follow-up (1 in intervention group, 3 in control group)

Source of funding: not stated

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "Randomization was accomplished using a computer program (permutation of blocks by generation of pseudo-random numbers with a rectangular distribution) in order to obtain homogeneity of groups"
Allocation concealment (selection bias)Low riskQuote: "The envelope method was used to decide which patients would undergo suturing of subcutaneous fat. Numbered envelopes contained the sealed information ‘Suture Yes’ or ‘Suture No’. The envelope was unsealed by the operating surgeon in the operation theater just before surgery"
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: this information was not available
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: this information was not available
Incomplete outcome data (attrition bias)
All outcomes
High riskComment: there were post-randomisation drop-outs and it is likely that these drop-outs would have had a clinically significant effect on the outcomes
Selective reporting (reporting bias)High riskComment: the trial protocol was not available, and this trial reported none of the primary outcomes of this review

Tamelis 2005

MethodsRandomised clinical trial
ParticipantsCountry: Lithuania
Number randomised: 130
Post-randomisation drop-outs: 9 (6.9%)
Revised sample size: 121
Average age: not stated
Male: female ratio: not stated
Inclusion criteria: people having colorectal surgery through a midline incision
Interventions

Participants randomly assigned to 2 groups
Group 1 (n = 66): subcutaneous closure (n = 61 after post-randomisation drop-out)
Group 2 (n = 64): no subcutaneous closure (n = 60 after post-randomisation drop-out)

Details of surgery including location and contamination: colorectal operations (contaminated or dirty)
Details of suture material: Maxon 3-0
Continuous or interrupted closure of subcutaneous tissue: not stated

Follow-up: 2 weeks after surgery

OutcomesWound infection
Notes

We contacted the trial authors in February 2013; the trial authors replied in March 2013

Reason for post-randomisation drop-out: died (2 in intervention group, 1 in control group); eventration (abnormal elevation of the diaphragm) (2 in each group); relaparotomy (1 in each group)

Source of funding: Surgery department (author replies)

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "The sequence was generated using computer (author replies)"
Allocation concealment (selection bias)Low riskQuote: "The identity of the trial arm was kept in a sequentially numbered, opaque, sealed envelopes (author replies)"
Blinding of participants and personnel (performance bias)
All outcomes
High riskQuote: "Our study was performed in double-blind fashion. It was performed by 2 investigators. The identity of the trial arm was kept in a sequentially numbered, opaque, sealed envelopes. The first investigator made randomisation of the patients randomly selecting envelope and opening it before operation. Neither second investigator (outcome assessor) nor the patient knew about method of wound closure - with subcutaneous suture or without (author replies)"
Comment: the surgeon was aware of the randomisation prior to operation.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskQuote: "Our study was performed in double-blind fashion. It was performed by 2 investigators. The identity of the trial arm was kept in a sequentially numbered, opaque, sealed envelopes. The first investigator made randomisation of the patients randomly selecting envelope and opening it before operation. Neither second investigator (outcome assessor) nor the patient knew about method of wound closure - with subcutaneous suture or without (author replies)"
Incomplete outcome data (attrition bias)
All outcomes
Low riskComment: there were post-randomisation drop-outs. Imputation by different scenarios did not change the conclusions
Selective reporting (reporting bias)High riskComment: the trial protocol was not available and the trial did not report all the primary outcomes of this review

Tiryakioglu 2010

  1. a

    Abbreviations

    > = greater than
    h = hour(s)

MethodsRandomised clinical trial
ParticipantsCountry: Turkey.
Number randomised: 82
Post-randomisation drop-outs: 3 (3.7%)
Revised sample size: 79
Average age: 63 years
Male:female ratio: 59 (74.7%): 20 (25.3%)
Inclusion criteria: people having elective saphenous vein graft excision for coronary artery bypass graft surgery
Interventions

Participants randomly assigned to 2 groups
Group 1 (n = 41): subcutaneous closure
Group 2 (n = 38): no subcutaneous closure

Details of surgery including location and contamination: saphenous vein graft excision (clean)
Details of suture material: Vicryl 2-0
Continuous or interrupted closure of subcutaneous tissue: continuous

Follow-up: 2 months after surgery

OutcomesWound infection
Notes

We attempted to contact the trial authors in February 2013
Reasons for post-randomisation drop-outs: died

Source of funding: not stated

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskComment: this information was not available
Allocation concealment (selection bias)Unclear riskComment: this information was not available
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: this information was not available
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: this information was not available
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskComment: there were post-randomisation drop-outs that might have made a clinically important difference to the treatment effect
Selective reporting (reporting bias)High riskComment: the trial protocol was not available and the trial did not report all the primary outcomes of this review

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
Deliaert 2009Not a comparison of subcutaneous versus no subcutaneous sutures
el Gamel 1994aParticipants had bilateral operations (vein excision from the legs) . Each participant had one wound randomised to subcutaneous closure and another wound randomised to no subcutaneous closure. The analysis did not take intra-participant correlation into account nor did the trial provide details to allow us to take the intra-participant correlation into account during meta-analysis.
Milewski 1980Quasi-randomised study (allocation by age of the participant)
Nouraei 2010No information regarding whether the subcutaneous layer was included in the single-layer closure method
Singer 2005No information regarding whether the subcutaneous layer was included in the single-layer closure method
Stenvik 2006No information regarding whether the groups differed in the method of skin closure
Teebken 2000No information regarding whether the groups differed in the method of skin closure

Characteristics of ongoing studies [ordered by study ID]

ChiCTR-TRC-11001152

Trial name or title ChiCTR-TRC-11001152
MethodsRandomised controlled trial
ParticipantsPeople undergoing abdominal surgery
InterventionsSubcutaneous suture versus no subcutaneous suture
Outcomeswound healing
Starting date1st October 2010
Contact informationXiao L: wuwei_07@hotmail.com
NotesCurrently recruiting according to Chinese Clinical Trial Registry and WHO Trial Registry details

Ancillary