Background: Asthma control is increasingly used as an outcome measure in asthma trials. Economic evaluations of asthma interventions require converting the impact on control to impact on resource use. The purpose of this study was to estimate the savings in direct costs by achieving asthma symptom control as defined in the Global Initiative for Asthma (GINA) 2014 management strategy.

Methods: Adolescents and adults with asthma were recruited through random digit dialing. Asthma control per GINA and the use of health-care resources were assessed at baseline and three-monthly visits up to one year. We used regression models to associate costs with symptom control, adjusting for potential confounding variables.

Results: The final sample included 517 individuals (average age 48.9, 65.8% female) with mostly mild-moderate asthma contributing 2,033 follow-up visits. In 598 (29.4%), 809 (39.8%), and 626 (30.8%) of visits asthma was symptomatically controlled, partially controlled, or uncontrolled, respectively. The average three-month costs of asthma were $134.5. Of these, 20.5% were attributable to inpatient care, 47.8% to outpatient care, and 31.5% to medication. Compared to controlled asthma, partially controlled asthma was associated with a non-significant increase of $9.5 (95%CI -$13.6 – $32.6) in adjusted three-month costs and uncontrolled asthma with a statistically significant increase of $81.7 (95%CI $48.5 – $114.9).

Conclusion: A substantial fraction of this population-based sample of largely mild-moderate asthmatics was symptomatically uncontrolled. Achieving symptom control was associated with a reduction in direct costs. The adjusted values from this study can be used to inform cost-effectiveness analyses of asthma treatments. This article is protected by copyright. All rights reserved.