ERAS Society guidelines have recommended that mechanical bowel preparation (MBP) should not be used for patients undergoing colonic surgery and that it should be used selectively for patients undergoing rectal surgery. This has been based on the fact that mechanical bowel preparation on its own did not impact on morbidity and mortality in these patients when compared with no bowel preparation or rectal enema alone.
This new meta-analysis has looked at the impact of oral luminal antibiotic preparation (OAB) on outcome in patients undergoing colorectal surgery. It has analysed data from both cohort studies (12 studies, 63,080 participants) and randomised controlled studies (28 studies, 6,437 patients). Although the addition of cohort studies may be considered to weaken the strengths of the conclusions, there have been a number of recent large cohort studies and these cannot be ignored. One of the strengths of this analysis is that it includes only one of the many NSQIP studies that have used the same database with overlapping cohorts of patients. Separate analyses have been presented for cohort and randomised controlled studies.
The meta-analysis has shown that a combination of MBP+OAB versus MBP alone was associated with a significant reduction in surgical site infection rates, anastomotic leak, 30-day mortality, overall morbidity and development of postoperative ileus, with no difference in Clostridium difficile infection rates. When a combination of MBP+OAB was compared with OAB alone, no significant difference was seen in SSI or anastomotic leak rates, but there was a significant reduction in 30-day mortality, and incidence of postoperative ileus with the combination. The study also found that there is minimal literature available on the comparison between combined MBP+OAB versus no preparation, OAB alone versus no preparation and OAB versus MBP. Whilst evidence arising from large retrospective cohort and database studies suggests a strong positive benefit, these are tempered when evidence arising from randomised controlled trials alone is considered. However, the evidence from randomised controlled trials suggests a benefit from OAB preparation in terms of SSI, which represents a major source of morbidity and increased healthcare costs.
The study suggests a potentially significant role for OAB preparation, either in combination with MBP or alone, in the prevention of postoperative complications in elective colorectal surgery, and perhaps, this may need revisiting the ERAS guideline recommendations.
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Professor Dileep Lobo
University of Nottingham, UK