Comparison of Acetylsalicylic Acid with Rivaroxaban or Alternative Anticoagulants for Thromboprophylaxis in Elective Total Hip Arthroplasty: A Retrospective Cohort Study.

Abstract

Background: The role of acetylsalicylic acid (ASA) thromboprophylaxis following elective total hip arthroplasty (THA) remains unclear, given limited high-quality evidence and differing guideline recommendations.

Objectives: To compare thromboprophylaxis prescribing patterns for ASA and alternative anticoagulants and to determine subsequent health care utilization for patients undergoing elective THA within one Canadian health region.

Methods: This retrospective cohort study involved adult patients who underwent THA between January and June 2019, comparing those who received ASA with those who received an alternative anticoagulant. Data for drug- and patient-specific characteristics are reported as means and standard deviations for continuous variables and as percentages for categorical variables. Patient characteristics and treatments were compared using χ² and t tests. Multivariable logistic regression was conducted to identify predictors of the choice of treatment (ASA vs rivaroxaban).

Results: Of the 180 patients who underwent THA in the study period, thromboprophylaxis consisted of ASA for 153 (85.0%) and rivaroxaban for 27 (15.0%). The most common ASA regimen was 325 mg daily (152/153, 99.3%) for a mean of 43.0 (standard deviation 6.9) days. Significant patient differences between the ASA and rivaroxaban groups included history of malignancy (6.5% vs 51.9%, p < 0.001), previous venous thromboembolism (0% vs 11.1%, p = 0.001), thrombophilia (0% vs 3.7%, p = 0.018), and chemotherapy (0% vs 11.1%, p < 0.001). Patients with a history of malignancy were more likely to receive rivaroxaban than ASA (odds ratio 31.65, 95% confidence interval 18.22 to 2.4 × 10⁴, p < 0.001). No differences were observed for health care utilization.

Conclusions: ASA was used as thromboprophylaxis after THA for most patients within one Canadian health region. Significant differences in baseline characteristics were noted between patients who received ASA and those who received rivaroxaban.