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

Abstract

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.

Figure 1.. PRISMA Flow Diagram for Data Collection

E indicates enema; IV, intravenous antibiotics; IVA, adequate IV antibiotics; IVB, IV antibiotics with incomplete aerobic and anaerobic cover; MBP, mechanical bowel preparation; OA, oral antibiotics; RCT, randomized clinical trial.

Figure 2.. Network Plot of Direct Comparisons for Surgical Site Infection

The size of the individual nodes represents the number of patients studied for each bowel preparation treatment option, and the thickness of the lines is proportional to the number of studies directly comparing the different nodes. E indicates enema; IV, intravenous antibiotics; IVA, adequate IV antibiotics; IVB, IV antibiotics with incomplete aerobic and anaerobic cover; MBP, mechanical bowel preparation; OA, oral antibiotics.

Figure 3.. Rankogram for Surgical Site Infection Results

The rankogram shows the probability of each preparation option being ranked best performing to worst performing. For example, intravenous antibiotics with oral antibiotics with or without enema (IV + OA ± E) has an 86% probability of being ranked best, 12.7% probability of being ranked second, and a less than 1% probability for the other options. In comparison, IV antibiotics (IV) alone has a 47% probability of being ranked third, 38% probability of being ranked fourth, 12% probability of being ranked fifth, 2.8% probability of being ranked sixth, and less than 1% probability of the other options. IVA indicates adequate IV antibiotics; MBP, mechanical bowel preparation; OA, oral antibiotics.

Figure 4.. Clustered Ranking Plot of Treatment Associations of Bowel Preparation With Surgical Site Infection (SSI) and Anastomotic Leaks (AL)

The colors represent different clusters. The clusters representing similar effects for treating SSI and AL are IV antibiotics and OA with or without an enema (IV + OA ± E), MBP with OA and adequate IV antibiotics (MBP + IVA + OA) (as the best-performing cluster) then IV antibiotics alone (IV), IV antibiotics with an enema (IV + E), MBP with IV antibiotics (MBP + IV), MBP with OA and IV antibiotics with incomplete aerobic and anaerobic cover (MBP + IVB + OA), OA alone (OA), and finally MBP + OA (as the worst-performing cluster). The surface area under the cumulative ranking (SUCRA) curve represents the overall rank for each treatment with regards to the likelihood of the outcome of interest. For IV + OA ± E, this is 98% for SSI and 90% for AL. In contrast, for IV, this is 61% for SSI and 45% for AL.