Can antibiotics as compared to placebo prevent postoperative wound infections after open groin hernia repair surgery?

Background

Groin hernia is a weakness in the abdominal wall in the groin area, through which soft tissue or organs can protrude. Groin hernias occur often and therefore groin hernia repair is one of the most frequently performed surgical operations worldwide. It is considered a 'clean' surgical technique with low postoperative wound infections rates and administration of antibiotics to patients undergoing open hernia repair surgery is therefore not generally recommended. Up to the 1990s, suture-based hernia repair (herniorrhaphy) was the method of choice. From then onwards hernia repair with a synthetic mesh (hernioplasty) gained increasing popularity and the debate as to whether antibiotics are needed to prevent postoperative wound infections started again.

Investigation

We searched the literature (12 November 2019) for randomised controlled trials comparing antibiotics versus placebo to prevent wound infections after open groin hernia repair surgery. We included both suture-based and mesh-type surgical methods. We divided infections into superficial and deep wound infections. Several studies revealed infection rates that were higher than the expected 5% for clean surgery. Therefore, we divided studies into a group with low infection rates (less than 5%) and one with high infection rates (more than 5%).

Study characteristics and key results

We identified five suture-based surgery studies and 22 mesh-type surgery studies. The suture-based studies were of very low methodological quality. The mesh-type surgery studies were of low to moderate methodological quality.

This review shows that antibiotics do not prevent the occurrence of any type of wound infections after suture-based hernia repair. For mesh-type hernia repair in a low infection risk environment, antibiotics probably make little to no difference in prevention of postoperative superficial wound infections. However, in a high infection risk environment it is uncertain whether antibiotics reduce the risk of superficial wound infection occurrence.

For deep wound infections, we show that antibiotics probably make little or no difference in reducing the risk in both a low and high infection risk environment.

Quality of the evidence

Evidence of very low quality shows that it is uncertain whether antibiotics reduce the risk of postoperative wound infections after suture-based hernia repair. Evidence of moderate quality shows that that antibiotics probably make little or no difference in preventing superficial or deep wound infections after mesh-type hernia repair in a low infection risk environment. Evidence of (very) low quality shows that antibiotics may reduce the risk of superficial wound infections, but not of deep wound infections after mesh-type hernia repair in a high infection risk environment.


Authors' conclusions: 

Evidence of very low quality shows that it is uncertain whether antibiotic prophylaxis reduces the risk of postoperative wound infections after herniorrhaphy surgery. Evidence of moderate quality shows that antibiotic prophylaxis probably makes little or no difference in preventing wound infections (i.e. all wound infections, SSSI or DSSI) after hernioplasty surgery in a low infection risk environment. Evidence of low quality shows that antibiotic prophylaxis in a high-risk environment may reduce the risk of all wound infections and SSSI, while evidence of very low quality shows that it is uncertain whether antibiotic prophylaxis reduces DSSI after hernioplasty surgery.

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Background: 

Inguinal or femoral hernia is a tissue protrusion in the groin region and has a cumulative incidence of 27% in adult men and of 3% in adult women. As most hernias become symptomatic over time, groin hernia repair is one of the most frequently performed surgical procedures worldwide. This type of surgery is considered 'clean' surgery with wound infection rates expected to be lower than 5%. For clean surgical procedures, antibiotic prophylaxis is not generally recommended. However after the introduction of mesh-based hernia repair and the publication of studies that have high wound infection rates the debate as to whether antibiotic prophylaxis is required to prevent postoperative wound infections started again.

Objectives: 

To determine the effectiveness of antibiotic prophylaxis in reducing postoperative (superficial and deep) wound infections in elective open inguinal and femoral hernia repair.

Search strategy: 

We searched several electronic databases: Cochrane Registry of Studies Online, MEDLINE Ovid, Embase Ovid, Scopus and Science Citation Index (search performed on 12 November 2019). We also searched two trial registers and the reference list of included studies.

Selection criteria: 

We included randomised controlled trials comparing any type of antibiotic prophylaxis versus placebo or no treatment for preventing postoperative wound infections in adults undergoing inguinal or femoral open hernia repair surgery (tissue repair and mesh repair).

Data collection and analysis: 

Two review authors independently selected studies, extracted data and assessed risk of bias. We separately analysed results for two different surgical methods (herniorrhaphy and hernioplasty). Several studies revealed infection rates that were higher than the expected 5% for clean surgery and we therefore divided studies into two subgroups: high infection risk environments (≥ 5% infection rate); and low infection risk environments (< 5% infection rate). We performed meta-analyses with random-effects models. We analysed three outcomes: superficial surgical site infections (SSSI); deep surgical site infections (DSSI); and all postoperative wound infections (SSSI + DSSI).

Main results: 

In this review update we identified and included 10 new studies. In total, we included 27 studies with 8308 participants in this review.

It is uncertain whether antibiotic prophylaxis as compared to placebo (or no treatment) prevents all types of postoperative wound infections after herniorrhaphy surgery (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.56 to 1.33; 5 studies, 1865 participants; very low quality evidence). Subgroup analysis did not change these results. We could not perform meta-analyses for SSSI or DSSI as these outcomes were not reported separately.

Twenty-two studies related to hernioplasty surgery (total of 6443 participants) and we analysed three outcomes: SSSI; DSSI; SSSI + DSSI.

Within the low infection risk environment subgroup, antibiotic prophylaxis as compared to placebo probably makes little or no difference for the outcomes 'prevention of all wound infections' (RR 0.71, 95% CI 0.44 to 1.14; moderate-quality evidence) and 'prevention of SSSI' (RR 0.71, 95% CI 0.44 to 1.17, moderate-quality evidence). Within the high infection risk environment subgroup it is uncertain whether antibiotic prophylaxis reduces all types of wound infections (RR 0.58, 95% CI 0.43 to 0.77, very low quality evidence) or SSSI (RR 0.56, 95% CI 0.41 to 0.77, very low quality evidence). When combining participants from both subgroups, antibiotic prophylaxis as compared to placebo probably reduces the risk of all types of wound infections (RR 0.61, 95% CI 0.48 to 0.78) and SSSI (RR 0.60, 95% CI 0.46 to 0.78; moderate-quality evidence).

Antibiotic prophylaxis as compared to placebo probably makes little or no difference in reducing the risk of postoperative DSSI (RR 0.65, 95% CI 0.26 to 1.65; moderate-quality evidence), both in a low infection risk environment (RR 0.67, 95% CI 0.11 to 4.13; moderate-quality evidence) and in the high infection risk environment (RR 0.64, 95% CI 0.22 to 1.89; low-quality evidence).

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