Patients with atrial fibrillation (AF) treated with once daily rivaroxaban had significantly better adherence and fewer gaps in treatment compared with those on twice daily apixaban, an observational study has found.

Data were obtained on patients with non valvular AF aged 18 or over who were treated with rivaroxaban or apixaban between June 2012 and April 2014. Overall 11,477 patients treated with rivaroxaban and 2,992 with apixaban were identified. Baseline demographic and clinical features were well matched for the two groups. Adherence to therapy was measured at 90 and 180 days. This was defined by the proportion of days covered (PDC) ≥ 0.80 and PDC ≥ 0.90. Gaps in supply of medication were also evaluated.

Relative to patients who received apixaban, those treated with rivaroxaban 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 compared with the apixaban group: 54.2% versus 62.4% (P < 0.001) and 40.0% versus 49.2% (P < 0.001), respectively.

The study aimed to compare adherence with rivaroxaban and apixaban in patients with non valvular AF in routine clinical practice. It did not address persistence with therapy. Compliance or adherence can be defined as the extent to which a patient acts in accordance with the prescribed interval, and dose of a dosing regimen. Medication persistence is a different concept which refers to the act of continuing the treatment for the prescribed duration.

The authors concluded that patients on a once daily regimen with rivaroxaban had significantly higher adherence and fewer gaps in treatment compared with twice daily apixaban. However, this study did not explore whether or not these differences translated into differences in patient outcomes.

More research in this area is needed to inform the optimal dosing strategy for these drugs.

Dr Peter Savill

McHorney CA, Peterson ED, Laliberte F et al. Comparison of adherence to rivaroxaban versus apixaban among patients with atrial fibrillation. Clin Ther 2016 Oct 24. pii: S0149-2918(16)30737-8. doi: 10.1016/j.clinthera.2016.09.014