Preoperative bathing or showering with skin antiseptics to prevent surgical site infection
Abstract
Background
Surgical site infections (SSIs) are wound infections that occur after invasive (surgical) procedures. Preoperative bathing or showering with an antiseptic skin wash product is a well‐accepted procedure for reducing skin bacteria (microflora). It is less clear whether reducing skin microflora leads to a lower incidence of surgical site infection.
Objectives
To review the evidence for preoperative bathing or showering with antiseptics for preventing hospital‐acquired (nosocomial) surgical site infections.
Search methods
For this fifth update we searched the Cochrane Wounds Group Specialised Register (searched 18 December 2014); the Cochrane Central Register of Controlled Trials (The Cochrane Library 2014 Issue 11); Ovid MEDLINE (2012 to December Week 4 2014), Ovid MEDLINE (In‐Process & Other Non‐Indexed Citations December 18, 2014); Ovid EMBASE (2012 to 2014 Week 51), EBSCO CINAHL (2012 to December 18 2014) and reference lists of articles.
Selection criteria
Randomised controlled trials comparing any antiseptic preparation used for preoperative full‐body bathing or showering with non‐antiseptic preparations in people undergoing surgery.
Data collection and analysis
Two review authors independently assessed studies for selection, risk of bias and extracted data. Study authors were contacted for additional information.
Main results
We did not identify any new trials for inclusion in this fifth update. Seven trials involving a total of 10,157 participants were included. Four of the included trials had three comparison groups. The antiseptic used in all trials was 4% chlorhexidine gluconate (Hibiscrub/Riohex). Three trials involving 7791 participants compared chlorhexidine with a placebo. Bathing with chlorhexidine compared with placebo did not result in a statistically significant reduction in SSIs; the relative risk of SSI (RR) was 0.91 (95% confidence interval (CI) 0.80 to 1.04). When only trials of high quality were included in this comparison, the RR of SSI was 0.95 (95%CI 0.82 to 1.10). Three trials of 1443 participants compared bar soap with chlorhexidine; when combined there was no difference in the risk of SSIs (RR 1.02, 95% CI 0.57 to 1.84). Three trials of 1192 patients compared bathing with chlorhexidine with no washing, one large study found a statistically significant difference in favour of bathing with chlorhexidine (RR 0.36, 95%CI 0.17 to 0.79). The smaller studies found no difference between patients who washed with chlorhexidine and those who did not wash preoperatively.
Authors' conclusions
This review provides no clear evidence of benefit for preoperative showering or bathing with chlorhexidine over other wash products, to reduce surgical site infection. Efforts to reduce the incidence of nosocomial surgical site infection should focus on interventions where effect has been demonstrated.
PICOs
Plain language summary
Preoperative bathing or showering with skin antiseptics to prevent surgical site infection
Surgical site infection is a serious complication of surgery and is usually associated with increased length of hospital stay for the patient, and also higher hospital costs. The use of an antiseptic solution for preoperative bathing or showering is widely practiced in the belief that it will help to prevent surgical site infections from developing. This review identified seven trials, with over 10,000 patients, that tested skin antiseptics (chlorhexidine solution) against normal soap or no presurgical washing. The review of these trials did not show clear evidence that the use of chlorhexidine solution before surgery was better than other wash products at preventing surgical site infections from developing after surgery.
Authors' conclusions
Summary of findings
| pre‐operative showering with Chlorhexidine 4% compared to placebo for surgical patients | ||||||
| Patient or population: surgical patients Settings: Hospitals Intervention: pre‐operative showering with Chlorhexidine 4% Comparison: placebo | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| placebo | pre‐operative showering with Chlorhexidine 4% | |||||
| Surgical site infection | Low risk population | RR 0.91 | 7791 | ⊕⊕⊕⊕ | ||
| 30 per 1000 | 27 per 1000 | |||||
| High risk population | ||||||
| 100 per 1000 | 91 per 1000 | |||||
| Allergic reaction | Study population | RR 0.89 | 3589 | ⊕⊕⊕⊝ | ||
| 6 per 1000 | 5 per 1000 | |||||
| Medium risk population | ||||||
| 3 per 1000 | 3 per 1000 | |||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. 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). | ||||||
| GRADE Working Group grades of evidence | ||||||
| 1 Some studies followed patients only until hospital discharge; however, as these studies are over 20 years old, we have assumed 7 days. | ||||||
| Chlorhexidine 4% compared to bar soap for Surgical patients | ||||||
| Patient or population: Surgical patients Settings: Intervention: Chlorhexidine 4% Comparison: bar soap | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| bar soap | Chlorhexidine 4% | |||||
| Surgical site infection | Study population | RR 1.02 | 1443 | ⊕⊝⊝⊝ | ||
| 136 per 1000 | 139 per 1000 | |||||
| Medium risk population | ||||||
| 128 per 1000 | 131 per 1000 | |||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. 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). | ||||||
| GRADE Working Group grades of evidence | ||||||
| 1 The method of allocation was unclear in some studies and outcome assessment was not blinded. | ||||||
| Chlorhexadine 4% compared to no wash for surgical patients | ||||||
| Patient or population: surgical patients Settings: Hospital Intervention: Chlorhexadine 4% Comparison: no wash | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| no wash | Chlorhexadine 4% | |||||
| Surgical site infection | Study population | RR 0.82 | 1142 | ⊕⊝⊝⊝ | ||
| 56 per 1000 | 46 per 1000 | |||||
| Medium risk population | ||||||
| 46 per 1000 | 38 per 1000 | |||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. 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). | ||||||
| GRADE Working Group grades of evidence | ||||||
| 1 Some studies followed patients only until hospital discharge; as the studies were over 20 years old, we have assumed this to be one week. | ||||||
Background
Surgical site infections (SSIs) are wound infections that occur after invasive (surgical) procedures. SSI is the third most frequently hospital‐acquired (nosocomial) infection amongst hospital patients (Smyth 2008). The Centers for Disease Control and Prevention (CDC) have used the National Nosocomial Infections Surveillance system (NNIS) to monitor nosocomial infections in acute care hospitals in the United States since 1970. Between 1986 and 1996 the CDC studied approximately 600,000 operations. Surgical site infections developed after three per cent (15,523) of these operations. During the period of data collection, 551 of the 15,523 patients who developed an SSI died, and 77% of deaths were attributed to the infection (Mangram 1999). More recently, summary of data from 30 hospitals in America, Asia, Africa and Europe found an overall SSI incidence of 2.3% (Rosenthal 2013). Apart from the morbidity and mortality associated with surgical site infections, there are significant cost implications. A study, using the NNIS system found that it cost over USD 3000 more to treat a patient with an SSI than a non‐infected patient . These costs were attributable to a greater likelihood of admission to an intensive care unit, a longer than usual post‐operative stay, and an increased rate of hospital re‐admission (Kirkland 1999). In Britain a study over a 2‐year period found the additional median cost attributed to a SSI was £5,239 (UKP)(Jenks 2014). Potential litigation is also a concern (Rubinstein 1999). Consequently, prevention of surgical site infection has become a priority for health care facilities.
An SSI is defined as an infection occurring within 30 days after an operation, and involves either a discharge of pus (purulent discharge), with or without laboratory confirmation; an organism isolated from an aseptically obtained culture; or signs and symptoms of infection, such as localised swelling, redness, or tenderness (Mangram 1999). The CDC have developed a set of standardised criteria for defining SSI in an attempt to make surveillance and rate calculation more accurate and amenable to comparison (Mangram 1999). SSIs are classified as being: superficial incisional (involving only skin or subcutaneous tissues); deep incisional (involving deeper soft tissue and fascia); or organ/space (involving any other part of the anatomy that was opened or manipulated). To help predict the likelihood, or SSI risk, surgical sites can be assessed preoperatively and classified into one of four categories with clear definitions: Class 1 (clean), Class II (clean‐contaminated), Class III (contaminated) and Class IV (dirty/infected) (Mangram 1999). Clean wounds are defined as uninfected surgical wounds in which the respiratory, alimentary, genital or uninfected urinary tract are not present and in which no inflammation is encountered. Non‐clean wounds are defined according to the anatomical area of operation, cause (aetiology) of wound, presence of existing clinical infection, and intra‐operative contamination. Since clean wounds are less likely to become infected, SSIs following clean surgery are usually associated with either: (1) patient risk factors, such as age, nutritional status, diabetes and obesity; (2) risk factors related to the procedure: including incomplete preoperative hand and forearm antisepsis by one of the surgical team, length of surgical procedure and surgical technique; or (3) risk factors associated with preoperative preparation of the patient: for example, antimicrobial prophylaxis, preoperative hair removal and preoperative antiseptic showering (Mangram 1999).
Skin is not sterile. Indeed, thousands of bacteria live permanently on skin and contribute to health by maintaining a steady colony that inhibits establishment of harmful yeast and fungal infections. These bacterial populations are referred to as the 'resident flora'. A number of bacteria are present on the skin for a short period due to transfer from other people or the environment, and these constitute the 'transient flora'. At present, whole body bathing or showering with skin antiseptic to prevent SSIs is a widespread practice before surgery. The aim of washing is to make the skin as clean as possible by removing transient flora and some resident flora. Chlorhexidine 4% in detergent ('Hibiscrub' or 'Hibiclens') or a triclosan preparation is usually used for this purpose, and there is evidence that the numbers of bacteria on the skin are reduced when it is applied (Derde 2012; Koburger 2010; Kaiser 1988). Moreover, use of a skin antiseptic on consecutive days not only reduces microbial counts from baseline measurements, but also reduces the counts progressively over time (Paulson 1993). Although this body of evidence demonstrates the effectiveness of antiseptics as skin cleansing agents, the more important question is whether preoperative bathing or showering with an antiseptic reduces the incidence of SSI. In a 10‐year prospective surveillance study, the SSI rate was lower amongst patients showering with hexachlorophene before surgery than in those who either did not shower or showered using a non‐medicated soap (Cruse 1980). In addition, at least two studies have used a before‐and‐after design to test the effect of introducing preoperative showering with triclosan to control methicillin‐resistant Staphylococcus aureus (MRSA) SSIs. In the first of these, showering before and after surgery was introduced to reduce the MRSA SSI rate. This intervention, however, was only one of a battery of measures introduced, so it was not possible to determine the independent effect of preoperative showering (Brady 1990). In the second, the incidence of MRSA SSI was reduced amongst orthopaedic patients after presurgical showering with triclosan was introduced, however, the patients were also treated with nasal mupirocin for five days before surgery (Wilcox 2003). Finally, a retrospective analysis of the incidence of SSI following a total hip or knee arthroplasty, over a two year period in two hospitals was undertaken (Colling 2014). In one hospital, patients were required to shower or bathe with an antiseptic on the night before and morning of surgery. There was no similar policy in the second hospital. Although there was no difference in the overall SSI incidence during the study, there was a reduction in Staphylococcus aureus and methicillin‐resistant Staphylococcus aureus SSI(Colling 2014). While these observational studies provide some support for the practice of preoperative showering with an antiseptic, the evidence is not definitive.
Patterns of resistance have developed with some antiseptics (Thomas 2000), leading to calls to restrict their use to situations where effectiveness can be demonstrated. In addition, hypersensitivity to chlorhexidine on the part of the patient is not uncommon. Consequently, the potential benefit of bathing or showering with antiseptics needs to be assessed alongside their potential for harm (Beaudounin 2004; Krautheim 2004). As it is unclear whether the use of antiseptics for preoperative bathing or showering leads to lower rates of SSIs, a systematic review is justified to guide practice in this area.
Objectives
To review the evidence for preoperative bathing or showering with antiseptics for the prevention of surgical site infections.
Methods
Criteria for considering studies for this review
Types of studies
All published and unpublished randomised controlled trials (RCTs) that allocate surgical patients individually, or by cluster, comparing any antiseptic preparation used for preoperative full body wash or showering, with non‐antiseptic preparations. Quasi‐randomised trials were not included (i.e. trials that allocate treatment by day of the week, medical record number, sequential admitting order etc.).
Types of participants
Men, women and children undergoing any type of surgery in any setting.
Types of interventions
Any type of antiseptic solution (any strength, any regimen, at any time before surgery) used for preoperative tub‐ or bed‐bathing or showering compared with:
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non‐antiseptic soap;
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non‐antiseptic soap solution;
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no shower or bath.
Antiseptic solutions were defined as liquid soap products containing an antimicrobial ingredient such as chlorhexidine, triclosan, hexachlorophene, povidone‐iodine or benzalkonium chloride. Trials comparing different types of antiseptic with each other would also be compared if preoperative showering with an antiseptic showed evidence of benefit.
Types of outcome measures
Primary outcomes
Surgical site infection. (Note: despite development of standardised criteria for defining SSI, the diagnosis of SSIs continues to vary between studies. We therefore accepted the definition used by the original authors to determine the proportion of patients who develop any SSI before or after discharge from hospital).
Secondary outcomes
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Mortality (any cause).
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Allergic reactions (e.g. contact dermatitis, anaphylaxis).
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Postoperative antibiotic use.
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Length of hospital stay.
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Re‐admission to hospital.
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Cost.
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Other serious infection or infectious complication, such as septicaemia or septic shock.
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Postoperative fever higher than 38o C on at least two occasions more than four hours apart, excluding the day of surgery.
Secondary outcomes were extracted from trial reports regardless of whether the primary outcome was reported. We excluded studies that measured only skin colonisation.
Search methods for identification of studies
Electronic searches
For an outline of the search methods used in the fourth update of this review see Appendix 1.
For this fifth update we searched the following electronic databases:
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The Cochrane Wounds Group Specialised Register (searched 18 December 2014);
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The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 11);
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Ovid MEDLINE (2012 to December Week 4 2014);
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Ovid MEDLINE (In‐Process & Other Non‐Indexed Citations December 18, 2014);
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Ovid EMBASE (2012 to 2014 Week 51);
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EBSCO CINAHL (2012 to 18 December 2014)
The following strategy was used to search CENTRAL:
#1 MeSH descriptor: [Skin] explode all trees 3486
#2 MeSH descriptor: [Antisepsis] explode all trees 101
#3 #1 and #2 23
#4 skin next antisep* 62
#5 MeSH descriptor: [Anti‐Infective Agents, Local] explode all trees 1691
#6 MeSH descriptor: [Soaps] explode all trees 179
#7 MeSH descriptor: [Povidone‐Iodine] explode all trees 409
#8 MeSH descriptor: [Iodophors] explode all trees 435
#9 MeSH descriptor: [Chlorhexidine] explode all trees 1376
#10 MeSH descriptor: [Alcohols] explode all trees 29960
#11 iodophor* or povidone‐iodine or betadine or chlorhexidine or triclosan or hexachlorophene or benzalkonium or alcohol or alcohols or antiseptic* or soap* or detergent* 18981
#12 MeSH descriptor: [Disinfectants] explode all trees 598
#13 #1 and #12 21
#14 skin near/5 disinfect* 128
#15 MeSH descriptor: [Detergents] explode all trees 299
#16 #1 and #15 51
#17 skin near/5 detergent* 34
#18 #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 or #11 or #13 or #14 or #16 or #17 46631
#19 MeSH descriptor: [Surgical Wound Infection] explode all trees 2837
#20 surg* near/5 infection* 5241
#21 surgical near/5 wound* 4315
#22 (postoperative or post‐operative) near/5 infection* 2386
#23 MeSH descriptor: [Preoperative Care] explode all trees 3539
#24 (preoperative or pre‐operative) next care 3951
#25 MeSH descriptor: [Perioperative Care] explode all trees 10389
#26 (perioperative or peri‐operative) next care 971
#27 #19 or #20 or #21 or #22 or #23 or #24 or #25 or #26 17697
#28 MeSH descriptor: [Baths] explode all trees 263
#29 shower* or bath* or wash* or cleans* 26111
#30 #28 or #29 26111
#31 #18 and #27 and #30 238
The search strategies for Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL can be found in Appendix 2, Appendix 3 and Appendix 4 respectively. The Ovid MEDLINE search was combined with the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity‐ and precision‐maximizing version (2008 revision); Ovid format (Lefebrve 2011). This filter is published in the Cochrane Handbook for Systematic Reviews of Interventions, Version 5.0.2 [updated September 2009]; Section 6.4.11. The EMBASE and CINAHL searches were combined with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN) (SIGN 2008). No date or language restrictions were applied.
Searching other resources
Reference lists of all retrieved articles were searched in order to identify additional studies. For the original version of the review, manufacturers of antiseptic products were contacted in order to obtain any unpublished data.
Data collection and analysis
Selection of studies
Both review authors independently assessed the titles and abstracts of references identified by the search strategy. Full reports of all potentially relevant trials were then retrieved for assessment of eligibility based on the inclusion criteria. Reference lists of retrieved studies were screened to identify further studies, which were also retrieved. Differences of opinion were settled by consensus or referral to the editorial base of the Wounds Group.
Data extraction and management
The following data were extracted from each study by both review authors independently using a piloted data extraction sheet: type of study, study setting, number of participants, sex, mean age, predisposing risk factors, type of antiseptic solutions, use of prophylactic antibiotics, procedure and timing for full body wash, period of community follow‐up, all primary and secondary outcome descriptions and outcome measures reported, including infection rates and study authors' conclusions.
Assessment of risk of bias in included studies
Two review authors independently assessed all included studies using the Cochrane Collaboration tool for assessing risk of bias (Higgins 2011). This tool addresses six specific domains, namely sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting and other issues (e.g. extreme baseline imbalance) (see Appendix 5 for details of criteria on which the judgement was be based for this review). Blinding and completeness of outcome data were assessed for each outcome separately. We completed a risk of bias table for each eligible study. Once again, disagreements between review authors were resolved by consensus or referral to the editorial base of the Wounds Group. When possible, contact was made with investigators of included trials to resolve any ambiguities.
We presented an assessment of risk of bias using a 'risk of bias summary figure', which presents all of the judgments in a cross‐tabulation of study by entry. This display of internal validity indicates the weight the reader may give the results of each study.
We defined high quality trials as those receiving a 'Low risk of bias' judgement for the domains of random sequence generation, allocation concealment and for blinding of outcome assessment.
Data synthesis
Analyses were performed using RevMan 5 software. Relative risks (RR) and 95% confidence intervals (CI) were calculated for dichotomous outcomes, and mean differences (MD) and 95% CI calculated for continuous outcomes. Results of comparable trials were pooled using the fixed‐effect model and 95% CI. Heterogeneity was investigated by calculating the I2 statistic (Higgins 2002). If evidence of significant heterogeneity was identified (i.e. a value greater than 50%), potential sources of heterogeneity were explored and a random‐effects approach to the analysis undertaken. A narrative review of eligible studies was conducted where statistical synthesis of data from more than one study was not possible, or considered inappropriate.
One trial used a multi‐centre design, but patients were allocated individually to the treatment or control arm (Rotter 1988). Two trials allocated clusters of patients to each intervention (Hayek 1987; Wihlborg 1987). In this review results were not analysed using the number of clusters as the unit of analysis but analysed as if the allocation was by individual. This was necessary because the authors of the trial did not use the cluster as the unit of analysis. Analysing cluster trials in this way has the potential to over‐estimate the effect of treatment (Mollison 2000).
Subgroup analysis and investigation of heterogeneity
The planned sub‐group analyses (one preoperative bath or shower compared with more than one preoperative bath or shower; and clean surgery compared with clean contaminated surgery) were not conducted due to the format of the reported data.
Sensitivity analysis
We included all eligible trials in the initial analysis and carried out sensitivity analyses to evaluate the effect of trial quality. This was done by excluding those trials most susceptible to bias based on the following quality assessment criteria: those with inadequate allocation concealment; or unblinded outcome assessment; or where blinding of outcome assessment was uncertain.
Results
Description of studies
For a detailed description of the included studies see Characteristics of included studies.
Our original search strategy identified 43 articles. Full‐text assessment was conducted for 16 potentially eligible papers. Seven of these papers were excluded from further review because the studies were not randomised, or were randomised trials evaluating other interventions (e.g. preoperative scrub solutions), or other outcomes (e.g. intraoperative wound colonisation) (Ayliffe 1983; Bergman 1979; Brandberg 1980; Garabaldi 1988; Leigh 1983; Newsom 1988; Wells 1983). The remaining nine citations referred to six trials, which reported outcomes for 10,007 participants, and were included in the review (Byrne 1992; Earnshaw 1989; Hayek 1987; Randall 1983; Rotter 1988; Wihlborg 1987). The results of these six trials were reported in nine publications (Byrne 1992; (Byrne 1994, Lynch 1992); Earnshaw 1989; Hayek 1987 (Hayek 1988); Randall 1983; Rotter 1988; Veiga 2008; Wihlborg 1987). Four authors of included trials (Byrne 1992; Earnshaw 1989; Randall 1983; Wihlborg 1987), and one non‐included trial author (Garabaldi 1988), responded to queries about study methods or requests for additional unpublished information, or both.
During the subsequent updates of this review we completed Risk of Bias and Summary of findings tables. We screened 87 citations for the updates and retrieved 13 full text studies for further assessment. Thirteen additional studies were excluded (Bode 2010; Colling 2014; Edminson 2010; Edmiston 2008; Eiselt 2009; Enjabert 1984; Jakobsson 2010; Kaiser 1988; Kalanter‐Hormozi 2005; Murray 2011; Paulson 1993; Tanner 2011; Veiga 2008). Details of these can be found in the Characteristics of excluded studies table. One trial of 150 participants met the inclusion criteria and was added to the review at the time of the second update (Veiga 2009).
Participants
The age range of the participants in the seven included studies was nine to 90 years old. The trials enrolled men, women and children booked for elective surgery.
Byrne 1992 included clean and potentially infected cases but all other studies were of clean surgery. Two studies included general surgical patients (Byrne 1992; Hayek 1987); one involved participants undergoing general, orthopaedic and vascular surgery (Rotter 1988); one enrolled participants scheduled for plastic surgical procedures (Veiga 2009) and one included biliary tract, inguinal hernia or breast surgery (Wihlborg 1987). The remaining studies involved only one type of surgery (Earnshaw 1989: vascular reconstruction; Randall 1983: vasectomy). Participants in the vasectomy study were day patients (Randall 1983).
Four of the centres in which the studies were conducted were in the United Kingdom (Byrne 1992; Earnshaw 1989; Hayek 1987; Randall 1983); one was in Sweden (Wihlborg 1987); one study was undertaken in Brazil (Veiga 2009); and one included a number of European centres (eight from Denmark, five from the United Kingdom, four from Sweden, two from Austria, and one each from Germany and Italy) (Rotter 1988).
While Veiga 2009 used CDC definitions for surgical site infection, all of the other studies included the presence of pus in their definition of infection. Earnshaw 1989 and Hayek 1987 also included patients with severe cellulitis (although there was only such patient), and Randall 1983 included patients with a discharge of serous fluid in his definition of infection.
Interventions
There were inconsistencies in both the interventions and the control procedures between studies. One trial compared a regimen that included three preoperative washes (Byrne 1992), three trials included a two‐wash regimen (Earnshaw 1989; Hayek 1987; Rotter 1988), and participants in three trials had only one wash preoperatively (Randall 1983; Veiga 2009; Wihlborg 1987).
The breakdown of the studies according to timing of bathing was as follows:
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One wash on admission, a second on the night before surgery and a third on the morning of surgery (Byrne 1992).
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One wash immediately after admission, and a second on the day of surgery (Hayek 1987).
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One wash on the day before surgery, and a second on the day of surgery (Rotter 1988).
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Two washes preoperatively, timing not specified (Earnshaw 1989).
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One wash on the day before surgery only (Wihlborg 1987).
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One wash not more than one hour before surgery (Randall 1983).
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One wash (with two applications of chlorhexidine detergent) two hours before surgery (Veiga 2009).
Three of the studies had two arms (Byrne 1992; Earnshaw 1989; Rotter 1988), whilst four had three arms (Hayek 1987; Randall 1983; Veiga 2009; Wihlborg 1987). The breakdown of studies according to bathing products was as follows:
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4% chlorhexidine gluconate (Hibiscrub/Riohex) detergent solution compared with a matching placebo (i.e. the same detergent without chlorhexidine) (Byrne 1992; Hayek 1987; Rotter 1988; Veiga 2009).
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4% chlorhexidine gluconate (Hibiscrub) compared with bar soap (Earnshaw 1989; Hayek 1987; Randall 1983).
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Chlorhexidine with no shower or bath (Randall 1983; Veiga 2009; Wihlborg 1987).
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Chlorhexidine full body bathing compared with localised washing, i.e. restricted to the part of the body to be subjected to surgery (chlorhexidine used in both arms of trial) (Wihlborg 1987).
Antibiotic prophylaxis was used routinely in only one study (Earnshaw 1989). In three other studies there was no attempt to alter the treating surgeons' usual routine for administering antibiotic prophylaxis but, in these studies, the reported rate of prophylactic antibiotic use was low (1% to 15%) (Byrne 1992; Rotter 1988; Wihlborg 1987). One trial excluded patients who were on antibiotics at the time of surgery but did not control for postoperative antibiotic use, which the trialists said was high (Veiga 2009). Two studies did not mention whether antibiotics were used before surgery (Hayek 1987; Randall 1983).
Outcome measures
Primary outcome
The primary outcome measure for this review, the effectiveness of preoperative washing or showering with an antiseptic in preventing SSI, was reported in all of the studies (Byrne 1992; Earnshaw 1989; Hayek 1987; Randall 1983; Rotter 1988; Veiga 2009; Wihlborg 1987).
Secondary outcomes
The secondary outcomes of the review were reported as follow:
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Mortality (any cause) was reported in two studies (Byrne 1992; Earnshaw 1989).
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Allergic reactions (e.g. contact dermatitis, anaphylaxis) were reported in two trials (Byrne 1992; Veiga 2009).
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Postoperative antibiotic use was not reported in any of the studies.
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Length of hospital stay was not reported in any of the studies.
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Re‐admission to hospital was not reported in any of the studies.
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Cost was reported in one study (Byrne 1992).
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Other serious infection or infectious complication, such as septicaemia or septic shock was not reported in any of the studies.
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Postoperative fever exceeding 38o C on at least two occasions more than four hours apart, excluding the day of surgery, was not reported in any of the studies
Sample size
None of the trials reported how the sample size was calculated.
Risk of bias in included studies
Two of the seven included studies were assessed as being overall at low risk of bias using the assessment criteria described above (a low risk of bias judgement for the criteria of random sequence generation, allocation concealment and blinding of outcome assessment) (Byrne 1992; Rotter 1988). (See Risk of Bias Figure 1; Figure 2).
Methodological quality graph: review authors' judgements about each methodological quality item presented as percentages across all included studies.
Methodological quality summary: review authors' judgements about each methodological quality item for each included study.
Allocation
Generation of random allocation sequence
All studies mentioned a process of randomisation. The method of generating the random allocation sequence was adequate in some studies (Byrne 1992; Randall 1983; Rotter 1988; Veiga 2009; Wihlborg 1987), and unclear in others (Earnshaw 1989; Hayek 1987). In four studies the random sequence was computer‐generated (Byrne 1992; Randall 1983; Rotter 1988; Veiga 2009). One study used block randomisation in groups of six using computer‐generated random numbers (Byrne 1992). A large multi‐centre study used cluster randomisation, whereby randomisation was carried out for each surgical unit in the study by means of computer‐generated numbers (Rotter 1988). Personal correspondence with authors of two of the studies confirmed that they used either computer‐generated random numbers (Randall 1983), or a randomisation list (Wihlborg 1987).
Allocation concealment
As with generation of the allocation sequence, concealment of allocation was adequate in some studies (Byrne 1992; Randall 1983; Rotter 1988; Wihlborg 1987), and unclear in others (Earnshaw 1989; Hayek 1987; Veiga 2009).
Blinding
Blinding of intervention
Blinding of intervention in three studies was by a double‐blind method (Byrne 1992; Rotter 1988; Veiga 2009). In one study there was single‐blinding of the intervention in two arms of the study but no blinding in the third arm of the study (Hayek 1987). In the remaining studies, there was no blinding of intervention (Earnshaw 1989; Randall 1983; Wihlborg 1987).
Blinding of outcome assessment
Five of the trials blinded outcome assessment (Byrne 1992; Earnshaw 1989; Hayek 1987; Rotter 1988; Veiga 2009). In one of the studies there was no blinding of the outcome assessment (Wihlborg 1987 personal communication). In one study it is unclear whether blinding of outcome assessment occurred (Randall 1983).
Incomplete outcome data
In one study analysis by intention‐to‐treat was not done (Byrne 1992). For all of the other studies it could not be determined whether analysis by intention‐to‐treat occurred (Earnshaw 1989; Hayek 1987; Randall 1983; Rotter 1988; Veiga 2009; Wihlborg 1987).
All of the studies reported the status of all people entered into the trials. One study reported only one of the 94 patients as lost to follow‐up (Randall 1983). Byrne 1992 reported a 99.4% completeness of follow‐up. All other studies reported that all patients were followed‐up (Earnshaw 1989; Hayek 1987; Rotter 1988; Veiga 2009; Wihlborg 1987). In one study, 140 patients out of the 2,953 enrolled were withdrawn from the study for several reasons: failure to have two preoperative showers, not meeting inclusion criteria, transferring out of unit, or no identification number on patient protocol (Rotter 1988). Despite this, the study reported on all remaining patients (n = 2813), resulting in 95.2% completeness of reporting.
Two authors recorded SSIs during hospitalisation and then followed patients for six weeks after hospital discharge (Byrne 1992; Hayek 1987), Rotter 1988 followed patients for three weeks, Randall 1983 for seven days, Veiga 2009 for 30 days; Wihlborg 1987 monitored SSIs that occurred in hospital and among those returning for an outpatient visit, and Earnshaw 1989 reviewed patients twice weekly until hospital discharge.
Effects of interventions
See: Summary of findings for the main comparison Preoperative showering with chlorhexidine 4% compared to placebo; Summary of findings 2 Chlorhexidine 4% compared with bar soap; Summary of findings 3 Chlorhexadine 4% compared with no wash
This review includes outcome data from seven trials with a total of 10,157 participants. Six comparisons were undertaken: chlorhexidine 4% versus placebo (Analysis: 01) (Byrne 1992; Hayek 1987; Rotter 1988; Veiga 2009); chlorhexidine 4% versus bar soap (Analysis: 02) (Earnshaw 1989; Hayek 1987; Randall 1983); chlorhexidine versus no bath or shower (Analysis: 03) (Randall 1983; Veiga 2009; Wihlborg 1987); whole body wash with chlorhexidine versus washing only that part of the body to be submitted to surgery (Analysis: 04) (Wihlborg 1987); more than one wash versus one wash (Analysis: 05) (Byrne 1992; Hayek 1987; Randall 1983; Rotter 1988); and one post hoc comparison, individual allocation versus cluster allocation (Analysis: 06) (Byrne 1992; Earnshaw 1989; Hayek 1987; Randall 1983; Rotter 1988; Wihlborg 1987). A random‐effect meta‐analysis was used when significant heterogeneity was present (i.e. where the I2 value was greater than 50%).
Chlorhexidine compared with placebo
This comparison includes four trials of 7791 participants and includes four outcomes (SSI, allergic reactions, mortality and cost) (Byrne 1992; Hayek 1987; Rotter 1988; Veiga 2009).
Surgical site infection
Participants in three of the trials had more than one wash (Byrne 1992; Hayek 1987; Rotter 1988); but in the Veiga 2009 trial participants had only one shower. Hayek 1987, Rotter 1988 and Veiga 2009 included patients having elective surgery, whereas Byrne 1992 included patients undergoing "clean or potentially infected surgery". It should be noted that in the Hayek 1987 trial the placebo was found to contain antimicrobial properties and was changed during the study. None of the individual trials found that washing with chlorhexidine had a statistically significant effect on SSI. All of the trials were included in the meta‐analysis. When compared with placebo, bathing with chlorhexidine did not result in a statistically significant reduction in the SSI rate (chlorhexidine 9.1%, placebo 10.0%); the relative risk (RR) was 0.91 (95% confidence interval (CI) 0.80 to 1.04) (Analysis 1.1).
Surgical site infection ‐ high quality trials
For this outcome we conducted a separate analysis of trials rated as high quality by the criteria described in the 'Methods of the Review' section ‐ namely Byrne 1992 and Rotter 1988 ‐ and obtained a similar result, the RR was 0.95 (95% CI 0.82 to 1.10) (Analysis 1.2). The event rate was 9.3% for the chlorhexidine group and 9.7% for the placebo group.
Mortality (any cause)
One trial in this comparison reported mortality data (Byrne 1992). A total of 23 patients died in the study period, but these were not reported in groups.
Allergic reaction
Two trials included allergic reaction as an outcome (Byrne 1992; Veiga 2009). No adverse reactions were reported by Veiga 2009. In the Byrne 1992 study 19 events were reported, nine (0.5%) in the chlorhexidine group and 10 (0.6%) in the placebo group. There was no evidence of a statistically significant difference in allergy rate (RR 0.89, 95% CI 0.36 to 2.19) (Analysis 1.3).
Cost
There was an estimate of cost in one study (Byrne 1992). The average total cost (based on drug costs, hotel costs, dressing costs and outpatients' costs) of patients washing with chlorhexidine was UK £936 compared with UK £897 when patients washed with a placebo. Standard deviations were not reported but, according to the authors, the difference was not statistically significant.
Chlorhexidine compared with bar soap
Three trials compared washing with chlorhexidine with washing with bar soap (Earnshaw 1989; Hayek 1987; Randall 1983). These included 1443 participants and reported on two outcomes (SSI and mortality). Due to small numbers in two of the trials (Earnshaw 1989; Randall 1983), and methodological inconsistencies in the Hayek 1987 trial, estimates of effect are imprecise and need to be interpreted with caution. Heterogeneity was high for this comparison (P value 0.08, I2 = 60%), so we used a random‐effects model for the meta‐analysis. There are two possible explanations for heterogeneity. First, different types of surgery were conducted in each trial; Earnshaw 1989 included patients undergoing vascular reconstruction, while Hayek 1987 included patients booked for routine elective surgery and Randall 1983 included only vasectomy patients. Alternatively, a different definition of SSI was used by Randall 1983, who included patients with a wound which discharged pus or serous fluid, whereas Earnshaw 1989 and Hayek 1987 defined SSI as the discharge of pus.
Surgical site infection
Two trials that compared washing with chlorhexidine with washing with soap found no difference between the treatments in postoperative SSI rate (Earnshaw 1989; Randall 1983). The largest trial (Hayek 1987), however, reported significantly fewer SSIs when patients washed preoperatively with chlorhexidine compared with those who washed with soap (RR 0.70, 95% CI 0.51 to 0.96) (Analysis 2.1). When results of the three trials were combined there was no statistically significant difference (RR 1.02, 95% CI 0.57 to 1.84) (Analysis 2.1), the event rate was 10.9% for chlorhexidine and 13.6% for bar soap.
Mortality (any cause)
Two patients died in the Earnshaw 1989 trial, but these were not reported by group.
Chlorhexidine compared with no wash
Three trials compared washing with chlorhexidine with no specific washing instructions (Randall 1983; Veiga 2009; Wihlborg 1987). These included 1142 patients and reported on SSI only. There was significant statistical heterogeneity between the three trials (P value < 0.03), and clinical heterogeneity (outpatient surgery versus inpatient surgery; different types of included patients). Randall 1983 enrolled patients undergoing vasectomy, Veiga 2009 included patients having plastic surgery and Wihlborg 1987 included patients undergoing elective surgery of the biliary tract, inguinal hernia or breast cancer. In addition, Randall 1983 defined SSI as a wound which discharged pus or serous fluid, Wihlborg 1987 defined SSI as the discharge of pus and Veiga 2009 defined SSI using Centers for Disease Control criteria for wound infection and wound classification.
Surgical site infection
Randall 1983 found no difference in the postoperative SSI rate between patients who washed with chlorhexidine compared with patients who did not wash preoperatively (12/32 (37.5%) patients in the chlorhexidine group developed an infection compared with 9/32 (28.1%) in the no wash group. In the Veiga 2009 trial, none of the patients in the no wash group developed a surgical site infection (0%) compared to one (0.2%) in the chlorhexidine group (RR 3.00; 95% CI 0.13 to 71.92). In the larger trial, Wihlborg 1987 found that a chlorhexidine wash when compared with no wash resulted in a statistically significant reduction in the number of patients with a SSI; (9 of the 541 (1.7%) patients in the chlorhexidine group developed an infection compared with 20 of 437 (4.6%) in the no wash group (RR 0.36; 95% CI 0.17 to 0.79) (Analysis 3.1). Although patients in the no‐wash groups were given no instructions to shower or bathe preoperatively, it is unclear whether any did so.
Chlorhexidine full wash compared with partial wash
One trial compared washing the whole body with chlorhexidine with a partial localised wash with chlorhexidine soap (Wihlborg 1987). This trial included 1093 participants and assessed one outcome; SSI.
Surgical site infection
Data from one trial making this comparison (Wihlborg 1987) showed a statistically significant reduction in SSIs when whole body washing (1.7%) was compared with partial localised washing (4.1%) (RR 0.40, 95% CI 0.19 to 0.85) (Analysis 4.1).
Summary of findings tables
To assess the overall body of evidence, we developed three Summary of findings' tables (4% chlorhexidine gluconate verus placebo; 4% chlorhexidine gluconate versus bar soap and 4% chlorhexidine gluconate versus no bath or shower), using GRADEprofiler. The quality of the body of evidence was assessed against five principle domains 1) limitations in design and implementation; 2) indirectness of evidence or generalisability of findings; 3) inconsistency of results ‐ for example unexplained heterogeneity and inconsistent findings; 4) imprecision of results where confidence intervals are wide; and 5) other potential biases, for example publication bias or high manufacturer involvement (Schunermann 2011).
Discussion
Widespread use of preoperative antiseptic washing agents to prevent SSI continues. This review summarises trial data from over 10,000 patients, that compared washing with chlorhexidine with either a placebo solution, or a bar soap, or no preoperative washing at all. There was no clear evidence that washing with chlorhexidine reduced the incidence of SSI. The results of the review are strengthened by the heterogeneous nature of the participants; the trials included men, women and children undergoing a range of surgeries that were either clean or potentially infected, and undertaken in both inpatient and outpatient settings. These studies were published over a 26‐year period between 1983 and 2009. The product used in the trials (chlorhexidine 0.4%) remains unchanged and the quality of the two largest trials (that included over 6,000 participants) was high, concealing the randomisation process and blinding the interventions. Both of these trials also included community follow‐up.
One of the limitations of the review was the quality of some of the studies. Community follow‐up was attempted in only four studies, only one of the authors provided justification for their sample sizes (Byrne 1992), and in both studies where a cluster design was used, analysis was conducted as if participants had been allocated individually. Nonetheless, the high quality trials and trials where participants were allocated individually, showed no statistically significant reduction in SSIs when chlorhexidine was used for preoperative washing.
Only one of the trials provided data for other important outcomes. Byrne 1992 assessed complications or undesirable effects attributable to the use of an antiseptic. In this trial patients assigned to chlorhexidine use were no more likely to suffer an adverse reaction than those assigned to the placebo group. There were no comparisons with bar soap for this outcome. Byrne 1992 also assessed the cost of washing with chlorhexidine compared with placebo and found a non‐significant cost reduction in the placebo group. Costs included length of hospital stay, so, even though the SSI rate was 1.1% higher in the placebo group, using a placebo still resulted in an overall cost benefit.
Our findings are consistent with two recent reviews of preoperative skin antiseptics for preventing surgical site infection. The first, which investigated any type of antiseptic preparation, included a section on pre‐operative body washing. The authors accepted both RCTs and non‐randomised comparative studies and found that showering with an antiseptic reduced skin flora but the effect on SSIs remained inconclusive (Kamel 2012). In the second review, Chlebicki 2013 included RCTs, quasi RCTs and pre/post intervention studies. A total of 16 clinical trials met their inclusion criteria and were incorporated in a meta analysis with two subgroups (clean surgery and clean contaminated/contaminated surgery). No benefit for chlorhexidine showering was found in either of the subgroups or in the overall estimate of effect; RR 0.90 (95% CI 0.77 to 1.05) (Chlebicki 2013).
Methodological quality graph: review authors' judgements about each methodological quality item presented as percentages across all included studies.
Methodological quality summary: review authors' judgements about each methodological quality item for each included study.
Comparison 1 Chlorhexidine 4% versus placebo, Outcome 1 Surgical site infection.
Comparison 1 Chlorhexidine 4% versus placebo, Outcome 2 Surgical site infection (high quality studies).
Comparison 1 Chlorhexidine 4% versus placebo, Outcome 3 Allergic reaction.
Comparison 2 Chlorhexidine 4% versus bar soap, Outcome 1 Surgical site infection.
Comparison 3 Chlorhexadine 4% versus no wash, Outcome 1 Surgical site infection.
Comparison 4 Chlorhexidine full wash versus partial wash, Outcome 1 Surgical site infection.
| pre‐operative showering with Chlorhexidine 4% compared to placebo for surgical patients | ||||||
| Patient or population: surgical patients Settings: Hospitals Intervention: pre‐operative showering with Chlorhexidine 4% Comparison: placebo | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| placebo | pre‐operative showering with Chlorhexidine 4% | |||||
| Surgical site infection | Low risk population | RR 0.91 | 7791 | ⊕⊕⊕⊕ | ||
| 30 per 1000 | 27 per 1000 | |||||
| High risk population | ||||||
| 100 per 1000 | 91 per 1000 | |||||
| Allergic reaction | Study population | RR 0.89 | 3589 | ⊕⊕⊕⊝ | ||
| 6 per 1000 | 5 per 1000 | |||||
| Medium risk population | ||||||
| 3 per 1000 | 3 per 1000 | |||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. 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). | ||||||
| GRADE Working Group grades of evidence | ||||||
| 1 Some studies followed patients only until hospital discharge; however, as these studies are over 20 years old, we have assumed 7 days. | ||||||
| Chlorhexidine 4% compared to bar soap for Surgical patients | ||||||
| Patient or population: Surgical patients Settings: Intervention: Chlorhexidine 4% Comparison: bar soap | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| bar soap | Chlorhexidine 4% | |||||
| Surgical site infection | Study population | RR 1.02 | 1443 | ⊕⊝⊝⊝ | ||
| 136 per 1000 | 139 per 1000 | |||||
| Medium risk population | ||||||
| 128 per 1000 | 131 per 1000 | |||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. 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). | ||||||
| GRADE Working Group grades of evidence | ||||||
| 1 The method of allocation was unclear in some studies and outcome assessment was not blinded. | ||||||
| Chlorhexadine 4% compared to no wash for surgical patients | ||||||
| Patient or population: surgical patients Settings: Hospital Intervention: Chlorhexadine 4% Comparison: no wash | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| no wash | Chlorhexadine 4% | |||||
| Surgical site infection | Study population | RR 0.82 | 1142 | ⊕⊝⊝⊝ | ||
| 56 per 1000 | 46 per 1000 | |||||
| Medium risk population | ||||||
| 46 per 1000 | 38 per 1000 | |||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. 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). | ||||||
| GRADE Working Group grades of evidence | ||||||
| 1 Some studies followed patients only until hospital discharge; as the studies were over 20 years old, we have assumed this to be one week. | ||||||
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Surgical site infection Show forest plot | 4 | 7791 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.91 [0.80, 1.04] |
| 2 Surgical site infection (high quality studies) Show forest plot | 2 | 6302 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.95 [0.82, 1.10] |
| 3 Allergic reaction Show forest plot | 2 | 3589 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.89 [0.36, 2.19] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Surgical site infection Show forest plot | 3 | 1443 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.57, 1.84] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Surgical site infection Show forest plot | 3 | 1142 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.26, 2.62] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Surgical site infection Show forest plot | 1 | 1093 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.40 [0.19, 0.85] |
