Safety, effectiveness, and health care cost comparisons among elderly patients with venous thromboembolism prescribed warfarin or apixaban in the United States Medicare population

Patrick Hlavacek, Jennifer D. Guo, Lisa Rosenblatt, Allison Keshishian, Cristina Russ, Jack Mardekian, Mauricio Ferri, Tayla Poretta, Huseyin Yuce, Robert D McBane

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Objective: To compare safety, effectiveness, and healthcare costs of major bleeding (MB), clinically relevant non-major (CRNM) bleeding, recurrent venous thromboembolism (VTE), and all-cause hospitalization among elderly Medicare VTE patients prescribed warfarin vs apixaban. Methods: Using 100% Medicare data, elderly patients prescribed apixaban or warfarin within 30 days after a VTE encounter were identified. Patients had continuous health plan enrollment and no parenteral or oral anticoagulant use ≤6 months preceding the VTE encounter. Cohorts were balanced using 1:1 propensity score matching (PSM). Cox proportional hazard models were used to assess the risk of MB, CRNM bleeding, recurrent VTE, and all-cause hospitalization. Generalized linear and two-part models were used to estimate MB-, recurrent VTE-, and all-cause related costs (per patient per month [PPPM]). Results: In the pre-matched cohort, 25,284 (66.9%) patients were prescribed warfarin and 12,515 (33.1%) apixaban. After 1:1 PSM, 11,363 matched pairs of apixaban-warfarin patients were included for a mean follow-up of 4.0 and 4.4 months, respectively. Matched cohorts had a mean age of 78 years and mean Charlson Comorbidity Index score of 2.9. Warfarin was associated with a higher risk of MB (hazard ratio [HR] = 1.31; 95% confidence interval [CI] = 1.10–1.57) and CRNM bleeding (HR = 1.31; 95% CI = 1.19–1.43) vs apixaban. The risks of recurrent VTE (HR = 0.96; 95% CI = 0.70–1.33) and all-cause hospitalization (HR = 1.05; 95% CI = 0.99–1.12) were similar among warfarin and apixaban patients. Warfarin patients had higher MB-related ($147 vs $75; p =.003) and all-cause costs PPPM ($3,267 vs $3,033; p <.001), but similar recurrent VTE-related medical costs PPPM ($30 vs $36; p =.516) vs apixaban patients. Conclusions: Warfarin was associated with significantly higher risk of MB and CRNM bleeding as well as higher MB-related and all-cause costs vs apixaban patients. Recurrent VTE risk and costs were similar among warfarin and apixaban patients.

Original languageEnglish (US)
JournalCurrent Medical Research and Opinion
StateAccepted/In press - Jan 1 2019



  • apixaban
  • major bleeding
  • recurrent VTE
  • VTE
  • Warfarin

ASJC Scopus subject areas

  • Medicine(all)

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