Risk Factors for Surgical Site Infection After Spinal Surgery: A Meta-Analysis

BACKGROUND: Surgical-site infection (SSI) after spinal surgery is the most common complication, which results in greater morbidity, mortality, and health care costs. Identifying risk factors of SSI is an important point for preventive strategies to reduce the incidence of SSI. The aim of this meta-analysis is to investigate the most important risk factors for SSI after spinal surgery. METHODS: PubMed, Embase, and Web of Science were systematically searched to identify cohort or case-control studies that investigated the risk factors for SSI following spinal surgery. A fixed-effects or random-effects model was used to pool the estimates, depending on the heterogeneity among the included studies. Heterogeneity between the studies was assessed by I-2 and Cochran's Q test. RESULTS: Twelve studies with a total of 13,476 patients met the inclusion criteria were included in this meta-analysis. Of them, 1 was a nested case-control studies, 7 were case-control studies, and 4 were cohort studies. The most important predictors of SSI were diabetes (risk ratio [RR] = 2.22, 95% confidence interval [95% CI] 1.38-3.60; P = 0.001), prolonged operative times (>3 hours) (RR = 2.16, 95% CI 1.12-4.19; P = 0.009), body mass index more than 35 (RR = 2.36, 95% CI 1.47-3.80; P = 0.000), and posterior approach (RR = 1.22, 95% CI 1.05-1.41; P = 0.009). CONCLUSION: Diabetes, prolonged operative times (>3 hours), body mass index more than 35, posterior approach, and number of intervertebral levels (>= 7) are associated with an increased risk of SSI after spinal surgery. Almost all these risk factors are in line with the known risk factors for SSI in patients who underwent spinal surgery.