Is Once Versus Twice Daily Dosing Better for Adherence in Asthma and Chronic Obstructive Pulmonary Disease?

Patients with asthma and chronic obstructive pulmonary disease (COPD) may be prescribed once- or twice-daily dosing of controller inhalers.

To assess differences in controller adherence by dosing schedule and age.

Electronic medication monitors (EMMs) captured the date and time of inhaler actuations over 90 days in patients using the Propeller Health platform. Prescribed inhaler schedule was self-reported. Once- versus twice-daily schedule comparisons were assessed retrospectively using regressions adjusting for age.

A total of 6294 patients with asthma and 1791 patients with COPD were included. On average, once-daily users had significantly higher median (interquartile range [IQR]) daily adherence than twice-daily users (asthma: 63.3 [IQR: 31.1, 86.7]% vs 50.3 [IQR: 21.1, 78.3]%, P < .001; COPD: 83.3 [IQR: 57.2, 95.6]% vs 64.7 [IQR: 32.8, 88.9]%, P < .001). This pattern persisted in all age groups, with the exception of 4- to 17-year-olds in asthma. The lowest adherence was in the young adult population (18- to 29-year-olds). The percentage of patients who achieved ≥80% adherence was significantly higher among once- versus twice-daily users in asthma (34.3% vs 23.6%, P < .001) and COPD (54.8% vs 38.6%, P < .001). The adjusted odds of once- versus twice-daily users achieving ≥80% adherence was 1.36 (95% confidence interval: 1.19-1.56, P < .001) in asthma and 1.73 (95% confidence interval: 1.38-2.17, P < .001) in COPD. Most once-daily patients with COPD took their medication in the morning versus at night; there was no difference in morning versus afternoon/evening administration in all other asthma and COPD groups.

Patients with asthma and COPD who were prescribed once-daily versus twice-daily medications were more likely to adhere to their inhalers. Patients with COPD had higher adherence than those with asthma, possibly reflecting, in part, the older cohort age. The effect of greater adherence on exacerbations is a topic for future analysis.