Network Meta-Analysis of Antibiotics and Bowel Preparation in Elective Colorectal Surgery

Authors List

Woodfield, J, University of Otago, Dunedin, New Zealand Clifford K, University of Otago, Dunedin, New Zealand Schmidt B, University of Otago, Dunedin, New Zealand Turner G, Dunedin Public Hospital, Dunedin, New Zealand  Amer M, Dunedin Public Hospital, Dunedin, New Zealand McCall, J, University of Auckland, Auckland, New Zealand

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

Aim
: Our aim was to summarise all data from randomised controlled trials(RCTs) meeting our selection criteria using network meta-analysis(NMA), to determine the ranking of different treatment strategies for their effects on postoperative outcomes.

Methods
: RCTs of adults undergoing different types of bowel preparation in elective colorectal surgery, with effective aerobic and anaerobic antibiotic cover, were selected for analysis. The search included Medline, Embase, Cochrane and SCOPUS databases before 2021 with no language restrictions. NMA was performed according to PRISMA guidelines. Data was extracted by two researchers and adjudicated by the lead investigator. Primary outcomes were incisional surgical site infections(ISSI) and anastomotic leak(AL). Secondary outcomes included other infections, mortality, ileus and side effects of preparation. Statistical analysis was performed in Stata v15.1 using frequentist routines.

Results
: Of 6,883 screened studies, 175 were assessed, with 35 RCTs including 8,377 patients being identified. Treatments compared IV(2,762 patients), IV+E(222 patients), IV+OA±E(628 patients), MBP+IV(2,712 patients), MBP+IV+OA(with good IV antibiotic cover 925 patients and with good overall antibiotic cover 375 patients), MBP+OA(267 patients) and OA(486 patients). The likelihood of ISSI was significantly lower for IV+OA±E (rank 1) and MBP+IV (good IV antibiotic cover)+OA (rank 2) compared to all other treatment options. The addition of oral antibiotics to intravenous antibiotics, both with and without mechanical bowel preparation, reduced incisional SSI by greater than 50%. There were minimal differences between treatments in AL and in any secondary outcomes.

Conclusions
: This NMA or RCTs supports the addition of oral antibiotics to intravenous antibiotics to reduce incisional SSI in elective colorectal surgery. This benefit was present both with and without the use of MBP.

References

JAMA Surgery 157(1);34-41,2022

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