Strategies for Antibiotic Administration for Bowel Preparation Among Patients Undergoing Elective Colorectal SurgeryA Network Meta-analysis

Question  When only using randomized clinical trial data, what is the most effective method of bowel preparation among patients undergoing elective colorectal surgery?

Findings  In this network meta-analysis, including data from 8377 patients from 35 randomized clinical trials, the addition of oral antibiotics to intravenous antibiotics (both with and without mechanical bowel preparation) was associated with a reduction in the incidence of incisional surgical site infection by greater than 50%. There were no differences in anastomotic leak or in other clinical outcomes.

Meaning  Bowel preparation should include the addition of oral antibiotics to intravenous antibiotics, as it may reduce incisional surgical site infection among patients undergoing elective colorectal surgery.

Importance  There are discrepancies in guidelines on preparation for colorectal surgery. While intravenous (IV) antibiotics are usually administered, the use of mechanical bowel preparation (MBP), enemas, and/or oral antibiotics (OA) is controversial.

Objective  To summarize all data from randomized clinical trials (RCTs) that met selection criteria using network meta-analysis (NMA) to determine the ranking of different bowel preparation treatment strategies for their associations with postoperative outcomes.

Data Sources  Data sources included MEDLINE, Embase, Cochrane, and Scopus databases with no language constraints, including abstracts and articles published prior to 2021.

Study Selection  Randomized studies of adults undergoing elective colorectal surgery with appropriate aerobic and anaerobic antibiotic cover that reported on incisional surgical site infection (SSI) or anastomotic leak were selected for inclusion in the analysis. These were selected by multiple reviewers and adjudicated by a separate lead investigator. A total of 167 of 6833 screened studies met initial selection criteria.

Data Extraction and Synthesis  NMA was performed according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines. Data were extracted by multiple independent observers and pooled in a random-effects model.

Main Outcomes and Measures  Primary outcomes were incisional SSI and anastomotic leak. Secondary outcomes included other infections, mortality, ileus, and adverse effects of preparation.

Results  A total of 35 RCTs that included 8377 patients were identified. Treatments compared IV antibiotics (2762 patients [33%]), IV antibiotics with enema (222 patients [3%]), IV antibiotics with OA with or without enema (628 patients [7%]), MBP with IV antibiotics (2712 patients [32%]), MBP with IV antibiotics with OA (with good IV antibiotic cover in 925 patients [11%] and with good overall antibiotic cover in 375 patients [4%]), MBP with OA (267 patients [3%]), and OA (486 patients [6%]). The likelihood of incisional SSI was significantly lower for those receiving IV antibiotics with OA with or without enema (rank 1) and MBP with adequate IV antibiotics with OA (rank 2) compared with all other treatment options. The addition of OA to IV antibiotics, both with and without MBP, was associated with a reduction in incisional SSI by greater than 50%. There were minimal differences between treatments in anastomotic leak and in any of the secondary outcomes.

Conclusions and Relevance  This NMA demonstrated that the addition of OA to IV antibiotics were associated with a reduction in incisional SSI by greater than 50%. The results support the addition of OA to IV antibiotics to reduce incisional SSI among patients undergoing elective colorectal surgery.