Perioperative Probiotics or Synbiotics in Adults Undergoing Elective Abdominal Surgery A Systematic Review and Meta-analysis of Randomized Controlled Trials

Objective: To define the impact of perioperative treatment with probiotics or synbiotics on postoperative outcome in patients undergoing abdominal surgery. Background: Postoperative surgical infection accounts for a third of all cases of sepsis, and is a leading cause of morbidity and mortality. Probiotics, prebiotics, and synbiotics (preparations that combine probiotics and prebiotics) are nutritional adjuncts that are emerging as novel therapeutic modalities for preventing surgical infections. However, current evidence on their effects is conflicting. Methods: A comprehensive search of the PubMed, Embase, and WHO Global Index Medicus electronic databases was performed to identify randomized controlled trials evaluating probiotics or synbiotics in adult patients undergoing elective colorectal, upper gastrointestinal, transplant, or hepatopancreaticobiliary surgery. Bibliographies of studies were also searched. The primary outcome measure was incidence of postoperative infectious complications. Secondary outcomes included incidence of noninfectious complications, mortality, length of hospital stay, and any treatment-related adverse events. Quantitative pooling of the data was undertaken using a random effects model. Results: A total of 34 randomized controlled trials reporting on 2723 participants were included. In the intervention arm, 1354 patients received prebiotic or symbiotic preparations, whereas 1369 patients in the control arm received placebo or standard care. Perioperative administration of either probiotics or synbiotics significantly reduced the risk of infectious complications following abdominal surgery [relative risk (RR) 0.56; 95% confidence interval (CI) 0.46-0.69; P < 0.00001, n = 2723, I-2 = 42%]. Synbiotics showed greater effect on postoperative infections compared with probiotics alone (synbiotics RR: 0.46; 95% CI: 0.33-0.66; P < 0.0001, n = 1399, I-2 = 53% probiotics RR: 0.65; 95% CI: 0.53-0.80; P < 0.0001, n = 1324, I-2 = 18%). Synbiotics but not probiotics also led to a reduction in total length of stay (synbiotics weighted mean difference: -3.89; 95% CI: -6.60 to -1.18 days; P = 0.005, n = 535, I-2 = 91% probiotics RR: -0.65; 95% CI: -2.03-0.72; P = 0.35, n = 294, I-2 = 65%). There were no significant differences in mortality (RR: 0.98; 95% CI: 0.54-1.80; P = 0.96, n = 1729, I-2 = 0%) or noninfectious complications between the intervention and control groups. The preparations were well tolerated with no significant adverse events reported. Conclusions: Probiotics and synbiotics are safe and effective nutritional adjuncts in reducing postoperative infective complications in elective abdominal surgery. The treatment effects are greatest with synbiotics.