Surgical Wound Infection Rates and Risk Factors in Spinal Fusion in a University Teaching Hospital in Madrid, Spain

Study Design. Prospective cohort study. Objective. To study risk factors linked to spinal fusion surgical wound infection (SWI) incidence and compare the incidence with rates in Madrid Region, Spain and United States as a whole. Summary of Background Data. SWI is one of the complications posed by spinal surgery. Indeed, spinal surgery has a higher infection rate than do other orthopedic surgeries such as total hip or knee arthroplasty. The study of risk factors that are susceptible to be modified will enable both the incidence of SWI and, by extension, related morbidity, mortality, and costs to be reduced. Methods. All patients undergoing spinal fusion at a tertiary hospital from June 2011 to June 2014 were included. Infection rate was calculated, and the association between risk factors and SWI incidence was assessed by reference to odds ratio (OR) with univariate and multivariate analysis. Results. The study population (n = 892) had a SWI rate of 3.9%. The standardized infection ratio of our hospital was 0.58 with respect to the Madrid Region, 0.76 with respect to Spain's national rate and 2.05 with respect to the US NHSN/CDC. The multivariate analysis showed that predictive factors of SWI were diabetes mellitus (OR 2.81, 95% confidence interval, CI: 1.186.72, P<0.05), chronic obstructive pulmonary disease (COPD) (OR 5.16, 95% CI: 2.04-13.08, P< 0.05), duration of surgery higher than the 75th percentile (OR 5.39, 95% CI: 1.77-110.84, P< 0.05) and dirty surgery (OR 14.01, 95% CI: 1.01- 28.88, P< 0.05). Conclusion. Independent risk factors for SWI in spinal fusion are existence of diabetes mellitus, COPD, duration of surgery higher than the 75th percentile and dirty surgery. Knowing these risk factors enables action to be taken to reduce the SWI rate.