Venous thromboembolism prophylaxis in shoulder surgery: a break-even cost-effectiveness study

Abstract

Background: Venous thromboembolism (VTE) is a serious complication following orthopedic shoulder surgery; however, research is limited involving the break-even cost-effectiveness of VTE prophylaxis. The purpose of this study was to determine whether the cost of aspirin and enoxaparin would break even for VTE prevention in patients following shoulder surgery.

Methods: A drug retail database was used to obtain the lowest price for a course of aspirin (81 mg) and enoxaparin (40 mg) to perform a break-even cost analysis. Our institutional purchasing records were then searched to estimate the cost of treating a symptomatic VTE. The TriNetX national database was queried to establish a rate of VTE after shoulder surgery. A break-even cost analysis was performed by determining the absolute risk reduction (ARR). This value was used to calculate the number of patients who are treated to prevent a single VTE while breaking even on cost. Sensitivity analyses were performed for drugs that did not break even at the database-derived VTE rates.

Results: Full medication courses of aspirin and enoxaparin were found to cost $1.18 and $125.37, respectively. The cost of treating a symptomatic VTE was determined to be $9407.00. Data from the TriNetX database showed rates of symptomatic VTE following shoulder arthroplasty, hemiarthroplasty, and arthroscopic rotator cuff repair of 1.60%, 1.50%, and 0.68%, respectively. Aspirin broke even on cost for all procedures if the initial rate decreased by an ARR of 0.01% (number needed to treat, 7972). Similarly, enoxaparin broke even for shoulder arthroplasty and hemiarthroplasty if the initial rate of VTE decreased by an ARR of 1.33% (number needed to treat, 75). Enoxaparin did not break even at the initial VTE rate for arthroscopic rotator cuff repair; however, sensitivity analysis found enoxaparin would break even if the drug could be obtained at a cost of ≤$60.00. Enoxaparin broke even if the cost of treating a symptomatic VTE was ≥$20,000.00.

Conclusions: The cost of a 3-week course of twice-daily aspirin or once-daily enoxaparin breaks even for VTE prophylaxis following shoulder arthroplasty and hemiarthroplasty if these drugs reduce the VTE rate by a calculated ARR. Given the lower rate of VTE observed for patients undergoing arthroscopic rotator cuff repair, only the 3-week course of aspirin broke even under these conditions. Once-daily enoxaparin did not break even at current market rate. Further research is needed to help determine optimal VTE prophylaxis after shoulder surgery.

Keywords: VTE; aspirin; economic modeling; enoxaparin; orthopedics; shoulder surgery.