Venous Thromboembolism Recurrence Among Patients Who Abandon Oral Anticoagulant Therapy in the USA: A Retrospective Longitudinal Study

Introduction: Among patients with venous thromboembolism (VTE), direct oral anticoagulants (DOACs) are recommended for preventing thromboembolic recurrence, complications, and mortality. This study compared the risk of VTE recurrence among patients who abandoned their first DOAC fill (“abandoners”) relative to patients who did not (“non-abandoners”). Methods: Adults with VTE who were prescribed DOACs were selected from Symphony Health, an ICON plc Company, PatientSource^®, April 1, 2017 to October 31, 2020. Patients who abandoned their first (index) DOAC fill were classified as abandoners and patients with an approved index DOAC fill as non-abandoners. Baseline characteristics were balanced between cohorts using inverse probability of treatment weighting. VTE recurrence based on the first post-index VTE event (deep vein thrombosis or pulmonary embolism) was ascertained and compared between cohorts using weighted Kaplan–Meier and Cox proportional hazard models during the follow-up period (i.e., index DOAC fill date to end of clinical activity or data availability). Results: After weighting, 152,443 and 153,931 patients comprised the abandoner and non-abandoner cohorts, respectively (mean age 60 years; 53% female; mean follow-up duration 15 months). After 3 months of follow-up, the probability of VTE recurrence was 7.74% in the abandoner cohort and 4.65% in the non-abandoner cohort; the risk of recurrence was 72% higher in the abandoner versus non-abandoner cohort (hazard ratio [95% confidence interval] 1.72 [1.64, 1.82]; p < 0.0001). At 12 months, the probability of recurrence was 9.91% in the abandoner cohort and 6.89% in the non-abandoner cohort; the risk of recurrence was 53% higher in the abandoner versus non-abandoner cohort (1.53 [1.46, 1.61]; p < 0.0001). Conclusion: Patients abandoning the first DOAC fill had significantly higher risk of VTE recurrence compared to patients who did not abandon the first fill. Ensuring proper access and encouraging early and continuous use of DOACs may help prevent severe and fatal complications among patients with VTE.