Achieving good adherence to inhaled corticosteroids after weighing canisters of asthmatic children

Background: The metered-dose inhalers (MDIs) currently available for inhaled corticosteroid delivery do not offer an integrated dose counter; therefore, it is difficult to evaluate adherence of patients. The present authors developed a linear regression equation using canister weight to calculate the number of doses actuated from the MDIs. This study aimed to assess medical adherence after the integration of regular weighing of the canisters into the routine service.  Methods: A cohort study was carried out between May 2013 and April 2014. Children aged less than 8 years with a diagnosis of asthma were recruited. The duration of adherence assessment was 24 weeks. Participants had a regular schedule every 8 weeks to obtain a new FLIXOTIDE® 125 inhaler. Parents were asked to collect the discarded MDI canisters, which were then weighed by a laboratory scale. The weight of each canister was replaced in the regression equation to calculate the number of doses actuated from the MDIs.  Results: A total of 52 asthmatic children participated in the study. The median age was 52.7 months. At the end of 24 weeks, 44, 33, and 23 discarded MDI canisters were collected from visits 1, 2, and 3, respectively. The median percentages of adherence were 96.8%, 96.3%, and 96.3%, respectively. In 11 discarded canisters (11%), the remaining medication was more than 30% of the labeled doses. Approximately 90% of the participants had no asthma exacerbation during 24-week study period.  Conclusion: High adherence rates were achieved after integration of canister weighing into the asthma care service.