Persistence with inhaled corticosteroids reduces the risk of exacerbation among adults with asthma: A real-world investigation

Background and objective: Real-world evidence suggests that persistence with inhaled corticosteroids (ICS), the mainstay of asthma drug therapy, is generally poor. The effect of persistence with ICS on the risk of asthma exacerbation was addressed in a population-based study. Methods: The cohort of 2335 beneficiaries of the National Health Service provided by the Italian Region of Lombardy, aged 18–40 years and newly treated with ICS during 2005–2008, was followed from their first ICS dispensation until 2010. Discontinuation of treatment with ICS and starting oral corticosteroid therapy during follow-up were respectively regarded as proxies of poor persistence with asthma medication and asthma exacerbation (outcomes). A proportional hazards model was fitted to identify predictors of ICS discontinuation. Case-crossover and case-case-time-control designs and conditional logistic regressions were used to estimate the association between persistence with ICS and asthma exacerbation. Results: Cumulative incidences of discontinuation were 36%, 57% and 78% at 6 months, 1 year and 5 years, respectively. Predictors of poor persistence were female gender, use of antibiotics during follow-up, absence of use of short-acting beta-agonists prior to and after starting treatment with ICS and starting and maintaining ICS monotherapy during follow-up. The odds ratios of asthma exacerbation (and 95% confidence intervals) associated with ICS exposure during the current period, contrasted with exposure during the reference period, were 0.4 (0.2, 0.9) and 0.3 (0.1, 1.0) from case-crossover and case-case-time-control estimates, respectively. Conclusion: Persistence with ICS treatment in adults with asthma reduces the risk of exacerbation in the real-life setting.