Longitudinal Rates, Patient Risk Factors, and Economic Impact of Superficial and Deep Incisional Surgical Site...

Longitudinal rates, risk factors, and costs of superficial and deep incisional surgical site infection (SSI) were evaluated six months after primary total hip arthroplasty (pTHA) and revision total hip replacement (rTHA). Patients who had pTHA or rTHA between January 1, 2016 and March 31, 2018 were identified using the IBM^® MarketScan^® administrative claims databases. Kaplan-Meier survival curves evaluated time to SSI over six months. Cox proportional hazard models evaluated SSI risk factors. Generalized linear models estimated SSI costs up to 12 months. The total cohort included 17,514 pTHA patients (mean [standard deviation] age 59.6 [10.1] years, 50.2% female; 66.4% commercial insurance), and 2,954 rTHA patients (61.2 [12.0] years, 52.0% female; 48.6% commercial insurance). Deep and superficial post-operative SSI at six months affected 0.30% (95% confidence interval [CI], 0.22%-0.39%) and 0.67% (95% CI, 0.55%-0.79% of patients in the pTHA, and 8.9% (95%CI: 7.8%-10.0%) and 4.8% (95% CI, 4.0%-5.6%) of patients in the rTHA cohorts. Hazards for SSI were related to patient comorbidities that included diabetes mellitus, obesity, renal failure, pulmonary or circulatory disorders, and depression. The adjusted average all-cause incremental commercial costs associated with post-operative infection ranged from $21,434 to $42,879 for superficial incisional SSI and $53,884 to $76,472 for deep incisional SSI, over a 12-month post-operative assessment period. The SSI rate after revision total hip arthroplasty (rTHA) was nearly 9% compared with 1.0% after pTHA. The risk of infection was influenced by several comorbid risk factors. The incremental cost associated with SSIs was substantial.