Differences in medication adherence by dosing schedule among patients with asthma

Patients with asthma may be prescribed once- or twice-daily dosing of controller inhalers. We assessed differences in controller adherence by dosing schedule and age. Inhaler use was assessed using electronic medication monitor (EMM) data collected from patients enrolled in Propeller Health. The EMM captured the date and time of inhaler actuations over 90 days. Prescribed dosing schedule was self-reported. Once- vs. twice-daily comparisons were assessed using regressions adjusting for age. 6,410 patients were included (mean (SD)) age: 34 (17.4) years; 32.6% with once-daily prescriptions. On average, once-daily users had significantly higher mean (SD) daily adherence compared to twice-daily users: 56.8 (32.4)% vs. 48.2 (31.7)%, p < 0.001. This pattern persisted by age group, with the exception of 4-17 year olds where no difference was observed (mean (SD)): 49 (30)% vs 48.4 (29.8)%, p = 0.77. Rescue medication use did not differ by dosing schedule. The percent of patients who achieved ≥ 80% adherence was significantly higher amongst once- vs. twice-daily users: 33.7% vs. 22.6%, p < 0.001. The adjusted odds of once- vs. twice-daily users achieving ≥ 80% adherence was 1.42 (95% CI: 1.24 - 1.62, p < 0.001) times higher. Patients with asthma who are prescribed once-daily (vs. twice-daily) schedules are more likely to adhere to their inhalers, even when controlling for age. Future work should explore the impact of dosing schedules on asthma control.