Adherence rate to inhaled corticosteroids and their impact on asthma control

Background:  Poor asthma control is associated to high morbidity. The objective of this study was to assess the association between adherence rates to beclomethasone dipropionate (BDP) and the degree of asthma control.
Methods:  A cohort concurrent study was carried out for 12 months with 122 asthmatic patients, aged 3–12 years, randomly selected in a pediatric pulmonology outpatient clinic, who received BDP free of charge. Adherence rates were verified by pharmacy records. Clinical control was assessed through a scoring system comprised four variables (nocturnal and morning symptoms, limitation of physical activities and exacerbations). Total score was 16 points. Patients whose score was below or equal to two were considered controlled (group 1), and patients whose score was above or equal to three were considered uncontrolled (group 2). For patients able to perform spirometry, we considered as controlled the patients with forced expiratory volume in 1 s (FEV₁) equal to or above 80% of the predicted value, and as uncontrolled the patients with FEV₁ below 80%.
Results:  Fewer than half (40.3% maximum) of the 122 patients maintained asthma control. Median adherence rate of groups 1 and 2 were 85.5% and 33.8%, ( P  < 0.001) in the 4th month, 90.0% and 48.0% ( P  < 0.001) in the 8th month and 84.4% and 47.0% in the 12th month ( P  < 0.001), respectively.
Conclusion:  In all periods, there were statistically significant differences in adherence rates for maintaining or not maintaining the asthma control. Optimal asthma control entailed adherence rate higher than 80%. Strategies for reducing asthma morbidity should include a regular monitoring of adherence to inhaled steroids.