OBJECTIVES : Surgical site infection after spinal surgery is the most common complication resulting in increased rates of morbidity and mortality. The aim of this study was to evaluate the rates of deep and superficial surgical site infections and associated costs for patients undergoing spinal surgery.

METHODS : This was a retrospective cohort study of patients undergoing spinal surgery between 2014 and 2017 using IBM® MarketScan® Commercial, Multi-State Medicaid and Medicare Supplemental databases. Patients demographic and clinical comorbidities as per the 31 domains of the Elixhauser Comorbidity Index were reported. The rates for new diagnoses of infection, categorized as deep or superficial within 6 months of spinal surgery were calculated. Generalized linear regression models were built and adjusted total payments over two-year period due to infection by category were estimated using least squares means. All payments were adjusted to 2017 consumer price-index.

RESULTS : A total of 31,416 patients with spinal surgery were included in the analysis. Most of the patients were between 45-64 years of age (54.9%), female (58.8%) and commercially insured (60.9%). Diabetes without complications (17.9), chronic pulmonary disease (13.6%) and peripheral vascular disease (5.2%) were the three most common comorbidities among patients undergoing spinal surgery. The overall rate of surgical site infections was 8.5% with 3.9% patients with deep infection and 4.6% patients with superficial infection. The mean adjusted total payments for commercially insured patients with deep and superficial infections were statistically significantly higher than those without infections, respectively ($303,835 and $227,115 vs $177,035, p<0.05) over the two-year period post-spinal surgery. Similar trend was observed among patients with Medicare and Medicaid insurances.

CONCLUSIONS : More than 8% of patients suffer from surgical site infection, of which 46% have deep infection following spinal surgery. Commercially insured patients with deep infection had nearly 72% increased costs as compared to those without infection.