Non-adherence and sub-optimal treatment with asthma medications in young adults: a population-based cohort study

OBJECTIVE Pharmacological treatment plays a key role in the management of asthma, but medication adherence is generally low. Our aim was to assess factors associated with dispensing patterns of, and adherence to, asthma medication in young adults with asthma. METHODS The study included young adults (age 22-24 years) from the Swedish population-based birth cohort BAMSE (n = 3,064) with linkage to register data on dispensed asthma medications and recorded diagnosis. Dispensing information was collected in January 2014-June 2019 (the study period) to cover the period of questionnaire data. Adherence to asthma medication was defined as refilling a prescription within 18 months. RESULTS In total, 234 individuals (7.6%) had asthma (doctor's diagnosis of asthma in combination with respiratory symptoms) and had been dispensed at least one prescription of asthma medication during the study period. Among them, 77% were dispensed a controller medication. The mean number of prescriptions dispensed per individual was higher in males than females (11.0 vs. 7.2; p < 0.01). The proportion of asthmatics with only a short-acting β2-agonist (SABA) dispensed was 22%, of which 33% were classified as having uncontrolled asthma. Adherence to controller medication was 60% and higher among those with an asthma diagnosis from specialized care than those diagnosed in primary care (RR 1.32 95% CI 1.03-1.69). Sex, socioeconomic status, and non-allergic comorbidity did not affect adherence. CONCLUSION Young adults with asthma had few prescriptions of asthma medication dispensed, indicating sub-optimal treatment. A considerable proportion was dispensed only SABA. Furthermore, adherence to controller medication was relatively low.