Risk factors for surgical site infection in patients undergoing colorectal surgery: A meta-analysis of observational studies

Objective Surgical site infection (SSI) is the second most prevalent hospital-based infection and affects the surgical therapeutic outcomes. However, the factors of SSI are not uniform. The main purpose of this study was to understand the risk factors for the different types of SSI in patients undergoing colorectal surgery (CRS). Methods PubMed, EMBASE, and Cochrane Library databases were searched using the relevant search terms. The data extraction was independently performed by two investigators using a standardized format, following the pre-agreed criteria. Meta-analysis for the risk factors of SSI in CRS patients was carried out using Review Manager 5.3 (RevMan 5.3) and Stata 15.1 software. The quality of evidence was evaluated using total sample size, Egger's P-value, and intergroup heterogeneity, which contained three levels: high-quality (Class I), moderate-quality (Class II/III), and low-quality (Class IV). The publication bias of the included studies was assessed using funnel plots, Begg's test, and Egger's test. Results Of the 2660 potentially eligible studies, a total of 31 studies (22 retrospective and 9 prospective cohort studies) were included in the final analysis. Eventually, the high-quality evidence confirmed that SSI was correlated with obesity (RR = 1.60, 95% confidence interval (CI): 1.47-1.74), ASA score >= 3 (RR = 1.34, 95% CI: 1.19-1.51), and emergent surgery (RR = 1.36, 95% CI: 1.19-1.55). The moderate-quality evidence showed the correlation of SSI with male sex (RR = 1.30, 95% CI: 1.14-1.49), diabetes mellitus (RR = 1.65, 95% CI: 1.24-2.20), inflammatory bowel disease (RR = 2.12, 95% CI: 1.24-3.61), wound classification >2 (RR = 2.65, 95% CI: 1.52-4.61), surgery duration >= 180 min (RR = 1.88, 95% CI: 1.49-2.36), cigarette smoking (RR = 1.38, 95% CI: 1.14-1.67), open surgery (RR =1.81, 95% CI: 1.57-2.10), stoma formation (RR = 1.89, 95% CI: 1.28-2.78), and blood transfusion (RR = 2.03, 95% CI:1.34-3.06). Moderate-quality evidence suggested no association with respiratory comorbidity (RR = 2.62, 95% Cl:0.84-8.13) and neoplasm (RR = 1.24, 95% Cl:0.58-2.26). Meanwhile, the moderate-quality evidence showed that the obesity (RR = 1.28, 95% CI: 1.24-1.32) and blood transfusion (RR = 2.32, 95% CI: 1.26-4.29) were independent risk factors for organ/space SSI (OS-SSI). The high-quality evidence showed that no correlation of OS-SSI with ASA score >= 3 and stoma formation. Furthermore, the moderate-quality evidence showed that no association of OS-SSI with open surgery (RR = 1.37, 95% CI: 0.62-3.04). The high-quality evidence demonstrated that I-SSI was correlated with stoma formation (RR = 2.55, 95% CI: 1.87-3.47). There were some certain publication bias in 2 parameters based on asymmetric graphs, including diabetes mellitus and wound classification >2. The situation was corrected using the trim and fill method. Conclusions The understanding of these factors might make it possible to detect and treat the different types of SSI more effectively in the earlier phase and might even improve the patient's clinical prognosis. Evidence should be continuously followed up and updated, eliminating the potential publication bias. In the future, additional high-level evidence is required to verify these findings.