Medication adherence in Medicare-enrolled older adults with asthma before and during the coronavirus disease 2019 pandemic

BACKGROUND: Data regarding medication adherence in older adults with asthma before and during the coronavirus disease 2019 (COVID-19) pandemic are lacking. OBJECTIVE: To evaluate medication adherence and determine factors associated with adherence in Medicare-enrolled older adults with asthma before and during the COVID-19 pandemic. METHODS: This was a retrospective cohort analysis of Medicare-enrolled patients with asthma. Medication adherence was measured using rates of proportion of days covered for dates January to July 2019 and January to July 2020. Patients less than 65 years of age, with chronic obstructive pulmonary disease, or with cystic fibrosis were excluded. Paired t tests assessed change in adherence between 2019 and 2020. Logistic regression evaluated association of age, sex, depression, moderate or severe asthma, use of a 90-day supply, having 3 or more albuterol fills, number of medications, medication-related problems, prescribers, pharmacies, controller medication classes, and systemic corticosteroid fills with high adherence (proportion of days covered ≥ 80%). RESULTS: Mean adherence to asthma controller medications ranged from 75% to 90%, in 2019. Adherence significantly decreased (P < .001) from 51% to 70% for all controller medications, except theophylline in 2020. Similar results were observed among patients with moderate or severe asthma. In 2019 and 2020, number of controller medications, 3 or more albuterol fills, and having a 90-day supply were associated with high adherence (P < .001). CONCLUSION: Adherence to asthma controller medications decreased considerably during the COVID-19 pandemic among Medicare-enrolled patients with asthma. Patients with markers for more severe asthma, overuse of albuterol, and a 90-day supply of controller medications were more likely to have high adherence. These findings can be used to identify opportunities to improve adherence and prescribing among adult patients with asthma.