Purpose: The aim of this study was to apply a propensity score approach to assess the long-term benefits of inhaled corticosteroids (ICS) on respiratory health in asthma.
Methods: This analysis was conducted on adults with persistent asthma from the Epidemiological study on the Genetics and Environment of Asthma, a 12-year follow-up study. ICS exposure was assessed by questionnaire. Change in lung function over the follow-up period, asthma control, and health-related quality of life (asthma quality of life questionnaire) were assessed by standardized and validated methods.
Results: Among 245 adults with persistent asthma, 78 (31.8%) were regularly/continuously exposed to ICS (≥6 months/year, ICS++ ) and 167 never/irregularly exposed to ICS (<6 months/year, ICS+/- ) over the follow-up period. Compared with ICS+/- subjects, a nonsignificant trend for a slower lung function decline (mL/year) was observed in ICS++ subjects (β [95%CI] = -11.4 [-24.9; 2.0]). The ICS++ subjects did not have better controlled asthma and higher health-related quality of life as compared with ICS+/- subjects.
Conclusions: Applying a propensity score method did not offer evidence of a statistical significant long-term benefit of ICS on respiratory health in adults with persistent asthma regularly or continuously exposed to ICS over a long period.
Keywords: asthma; indication bias; inhaled corticosteroids; long-term effects; pharmacoepidemiology; propensity score; respiratory health.
Copyright © 2014 John Wiley & Sons, Ltd.