Clinical burden of asynchrony in patients with asthma when using metered-dose inhalers for control

Background: Asynchrony, or lack of coordination between inhalation and actuation when using a pressurized metered-dose inhaler (MDI), could theoretically impact the delivery of inhaled medications and treatment efficacy. Objective: To assess the real-world association between asynchrony and clinical outcomes among patients with asthma who receive controller therapy delivered by MDIs. Methods: A cohort of patients was assembled via electronic health records. The patients were aged ≥12 years, with one or more documentations of an asthma diagnosis, no diagnosis of chronic obstructive pulmonary disease, and two or more prescriptions for an inhalation aerosol corticosteroid alone or with long-acting beta-2-agonist delivered via MDI. Their inhaler technique, demonstrated by using a placebo MDI, was evaluated at a clinic visit by study nurses who used a standardized 10-step checklist. Asynchrony was defined as any gap in timing between inhalation and actuation. Clinical outcomes were assessed via electronic health records during the 6 months before the clinic visit and were compared between patients with and patients without asynchrony by using multivariable regression analyses adjusted for age, gender, asthma severity proxy, and baseline comorbidities. Results: Of the total 254 eligible patients, mean age of 49.3 years, 90 males (35.4%), 32 (12.6%) had asynchrony. Patients with asynchrony had higher odds of an asthma exacerbation (adjusted odds ratio, 2.99; p = 0.009), and lower odds of risk domain asthma control (adjusted odds ratio, 0.41; p = 0.04) compared with patients without asynchrony. Conclusion: This study provided real-world evidence that asynchrony in MDI use among patients with asthma who were treated with controller MDIs was associated with clinical burden in terms of asthma exacerbations and control.