Purpose: Non-vitamin K antagonist oral anticoagulant medications are increasingly used for stroke prophylaxis in patients with nonvalvular atrial fibrillation (NVAF). This study aimed to compare adherence with rivaroxaban and apixaban among patients with NVAF in routine clinical practice.
Methods: Using pharmacy and medical claims from Truven Health Analytics MarketScan databases, we identified NVAF patients aged ≥18 years treated with rivaroxaban or apixaban. Baseline demographic and clinical features were balanced using 1:1 propensity score matching. Adherence to therapy was measured at 90 and 180 days post-index date and was defined by the proportion of days covered (PDC) ≥0.80 and PDC ≥0.90. "Gaps in care," defined as those with 10 or more day gaps in supply, were also evaluated.
Findings: Between June 2012 and April 2014, 11,477 rivaroxaban and 2992 apixaban users were identified. Baseline characteristics for rivaroxaban and apixaban users were well matched. Relative to apixaban users, rivaroxaban users were more likely to have a PDC ≥0.80 at both 90 days (85.3% vs 79.9%; P < 0.001) and 180 days (75.8% vs 72.2%; P = 0.001). Similar results were observed with PDC ≥0.90. The proportion of patients with at least one 5+ and 10+ day gap in prescriptions was significantly lower in the rivaroxaban versus apixaban cohorts: 54.2% versus 62.4% (P < 0.001) and 40.0% versus 49.2% (P < 0.001), respectively.
Implications: Adherence to non-vitamin K antagonist oral anticoagulants among NVAF patients is less than ideal, and gaps in treatment are common. Those on once-a-day rivaroxaban had significantly higher adherence and fewer gaps in treatment compared with twice-a-day apixaban. Future studies are needed to explore whether these treatment differences affect comparative patient outcomes.
Keywords: adherence; anticoagulant; apixaban; atrial fibrillation; rivaroxaban.
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