Has network meta-analysis resolved the controversies related to bowel preparation in elective colorectal surgery?

AIM: There are discrepancies in the guidelines on preparation for colorectal surgery. While intravenous antibiotics (IV) are usually administered, the use of mechanical bowel preparation (MBP) and/or oral antibiotics (OA) is controversial. A recent network meta-analysis (NMA) demonstrated that the addition of OA reduced incisional surgical site infections (iSSIs) by more than 50%. We aimed to perform a NMA including only the highest quality randomized clinical trials (RCTs) in order to determine the ranking of different treatment strategies and assess these RCTs for methodological problems that may affect the conclusions of the NMAs. METHOD: A NMA was performed according to PRISMA guidelines. RCTs of adult patients undergoing elective colorectal surgery with appropriate antibiotic cover and with at least 250 participants recruited, clear definition of endpoints and duration of follow-up extending beyond discharge from hospital were included. The search included Medline, Embase, Cochrane and SCOPUS databases. Primary outcomes were iSSI and anastomotic leak (AL). Statistical analysis was performed in Stata v.15.1 using frequentist routines. RESULTS: Ten RCTs including 5107 patients were identified. Treatments compared IV (2218 patients), IV + OA (460 patients), MBP + IV (1405 patients), MBP + IV + OA (538 patients) and OA (486 patients). The likelihood of iSSI was significantly lower for IV + OA (rank 1) and MBP + IVA + OA (rank 2), reducing iSSIs by more than 50%. There were no differences between treatments for AL. Methodological issues included differences in definition, assessment and frequency of primary endpoint infections and the limited number of participants included in some treatment options. CONCLUSION: While this NMA supports the addition of OA to IV to reduce iSSI it also highlights unanswered questions and the need for well-designed pragmatic RCTs.

Strategies for Antibiotic Administration for Bowel Preparation Among Patients Undergoing Elective Colorectal Surgery: A Network Meta-analysis.

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.