Abstract
BACKGROUND: Regular use of inhaled corticosteroids (ICS) is a cornerstone of asthma treatment. Adherence to ICS has been suggested to be poor and be associated with poor asthma control and exacerbations. OBJECTIVE: To evaluate adherence to ICS and its relation to asthma symptom control and exacerbations in adult patients with asthma using ICS regularly. METHODS: Altogether, 411 Finnish adult asthmatics who reported using regular/daily ICS were included. Comprehensive prescription and dispensation data from national records were obtained. Adherence (%) to ICS was calculated individually [(dispensed ICS µg /prescribed ICS µg) x100] during the follow-up time. Asthma control was assessed by the Asthma Control Test (ACT). Exacerbations were assessed over the previous 12 months by a questionnaire. RESULTS: Median prescribed daily ICS dose was 1000 (IQR 750–1500) µg and median dispensed dose was 784 (IQR 489–1008) µg equivalent to beclomethasone dry-powder inhaler, yielding a median adherence of 76.0 (53.2–98.8) % during the follow-up. Regarding asthma exacerbations during the previous year, 66.7% of the responders had temporarily increased their asthma medication, 32.7% had a course of oral corticosteroid, 22.7% had unscheduled health care visit and 2.5% were hospitalised for asthma. Poor adherence was not associated with any of these event types. There was no correlation between adherence to ICS and ACT scores (Pearson Correlation coefficient r = 0.011, p = 0.822). CONCLUSIONS: Adherence to ICS treatment among asthmatics in Finland is high, and poor asthma control or asthma exacerbations are not related to poor adherence. Rather, exacerbating asthma patients seem to have better adherence to ICS. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12890-026-04223-0.