Predictors of Higher Costs Following Reverse Total Shoulder Arthroplasty.

Objectives: The rising popularity of reverse total shoulder arthroplasties (RTSA) demands attention to its growing costs on the healthcare system, especially with the implementation of bundled payments. Charges associated with patients' inpatient stays can be mitigated with a better understanding of the drivers of cost following RTSA. In this study, we evaluate potential pre-operative and post-operative factors associated with higher inpatient costs following RTSA. Methods: We identified 59,925 patients who underwent RTSA using the National Inpatient Sample between 2016 and 2019. Total inpatient hospital charges were collected, and patients were divided into "normal cost" or "high cost" groups. The high cost group was defined as patients with total costs greater than the 75th percentile. Univariate and multivariate analyses were performed on pre-operative demographic and comorbidity variables as well as post-operative surgical and medical complications to predict factors associated with higher costs. T-tests and Chi-squared tests were performed, and odds ratios were calculated. Results: The mean total charges were $141.213.93 in the high cost group and $59,181.94 in the normal cost group. Following multivariate analysis, non-white patients were associated with higher costs by 1.31-fold (P<0.001), but sex and age were not. Cirrhosis and non-elective admission had higher odds of higher costs by 1.56-fold (P<0.001) and 3.13-fold (P<0.001), respectively. Among surgical complications, there were higher odds of high costs for periprosthetic infection by 2.43-fold (P<0.001), periprosthetic mechanical complication by 1.28-fold (P<0.001), and periprosthetic fracture by 1.56-fold (P<0.001). Medical complications generally had higher odds of high costs than surgical complications, with deep vein thrombosis having nearly five times (P<0.001) and myocardial infarction almost four times (P<0.001) higher odds of high inpatient costs. Conclusion: Post-operative medical complications were the most predictive factors of higher cost following RTSA. Pre-operative optimization to prevent infection and medical complications is imperative to mitigate the economic burden of RTSA's.