Authors' objectives:

This review evaluates the relative efficacy of antimicrobial prophylaxis in patients undergoing colorectal surgery where there is a high risk of surgical wound infection (SWI).

Authors' results and conclusions: The quality of the RCTs has improved over the last 12 years, though there are still many methodological problems, including inappropriate method of patient allocation, lack of blinding during outcome assessment, and insufficient sample size. The criteria for inclusion and exclusion were described in 87% of the included trials. The exclusion criteria most frequently used were allergy to study drugs, preoperative use of other antibiotics, impaired renal or liver function, children or very old patients, pregnancy or lactation, and certain types of colorectal operations. More than 70 different antibiotic regimens were tested in 147 trials. The overall rate of SWI across all the included trials of antimicrobials prophylaxis (excluding four non-antibiotic groups) was 11.1% (n = 22,927). The results of this review confirm that the use of antimicrobial prophylaxis is generally effective for the prevention of SWIs in colorectal surgery. Some antimicrobial regimens appear to be less effective than others in this indication. For example, monotherapy with either metronidazole, doxycycline or piperacillin are inadequate for prophylactic treatment in colorectal surgery. The review found that a single dose or short-term use of an antimicrobial agent is as efficacious as long-term, postoperative use. Pooled results from 17 trials that compared a single-dose regimen with a multiple-dose regimen, showed no significant difference in the rate of SWI (odds ratio = 1.17; 95% confidence interval [CI]: 0.89, 1.54). There is a lack of convincing evidence concerning the importance of a second-dose regimen when surgical procedures are longer than 2 hours. There is no convincing evidence to suggest that the second- and third-generation cephalosporins are more efficacious than the first-generation cephalosporins in this indication (6% versus 6.4%; odds ratio = 0.93; 95% CI: 0.46, 1.86). Establishing the efficacy of different routes of administration of antibiotic prophylaxis was complicated by the use of different antibiotics or use of extra antibiotics. No additional benefit was observed in six trials that compared parenteral alone, with parenteral plus topical use of antibiotic prophylaxis. Several trials, showing extra benefit of oral antibiotics, used inadequate parenteral antibiotics such as metronidazole alone, or piperacillin alone. Oral or topical application of antibiotics in addition to the parenteral administration of appropriate antibiotics seem to be of limited value in most cases. In general, the estimates of efficacy of many of the different regimens included are similar and it is very difficult, if not impossible, to identify the best one. However, the Type-II error or lack of statistical power cannot be ruled out as a potential reason for statistically non-significant findings in many small trials. A total of 74 of the 134 trials published in English reported adverse events following antibiotic prophylaxis in colorectal surgery. Skin rash, diarrhoea, and nausea were commonly mentioned adverse events that may be attributable to the use of some antibiotic treatments. No serious toxicity or adverse events were reported except in one trial that reported postoperative bleeding in some patients treated with latamoxef.

Authors' recommendations: The use of antimicrobial prophylaxis is efficacious in the prevention of SWI in colorectal surgery. With the exception of a few inadequate regimens, there is no significant difference in the rate of SWI between many regimens. The use of a multiple-dose regimen may be unnecessary for the prevention of SWI, as single-dose regimens have been demonstrated to be as efficacious as multiple dosing and in addition, may be associated with less toxicity, fewer adverse events, less risk of developing bacterial resistance and lower costs. Similarly, no convincing evidence supports the idea that the new-generation cephalosporins are more efficacious than first-generation cephalosporins in preventing SWI in colorectal surgery.

Authors' methods: Systematic review

Project Status: Completed

URL for project: http://www.hta.ac.uk/948

Year Published: 1998

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: England, United Kingdom

Organisation Name: NIHR Health Technology Assessment programme

Contact Address: NIHR Journals Library, National Institute for Health and Care Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK

Contact Name: journals.library@nihr.ac.uk

Contact Email: journals.library@nihr.ac.uk

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