Atopy Modifies the Association Between Inhaled Corticosteroid Use and Lung Function Decline in Patients with Asthma

Inhaled corticosteroids (ICSs) are the mainstay of asthma treatment, but response to medication is variable. Patients with allergic inflammation generally show a better short-term response to ICSs; however, studies on predictors of long-term response are few.

To assess whether allergic sensitization can modify the association between ICS use and lung function decline over 20 years in adult asthma.

We used data from the 3 clinical examinations of the European Community Respiratory Health Survey. We measured ICS use (no use, and use for <1.3, 1.3-8, and >8 years) and FEV₁ decline among subjects with asthma over the 2 periods between consecutive examinations. We conducted a cohort study combining data of the 2 periods (906 observations from 745 subjects) to assess whether the association between ICS use and FEV₁ decline was modified by allergic sensitization (IgE > 0.35 kU/L for any of house-dust mite, timothy grass, cat, or Cladosporium).

FEV₁ decline was similar for non-ICS users, as well as ICS users for less than 1.3 years, with and without allergic sensitization. However, among subjects on ICSs for a longer period, sensitization was associated with an attenuated decline (P_interaction = .006): in the group treated for more than 8 years, FEV₁ decline was on average 27 mL/y (95% CI_{Bonferroni-adjusted}, 11-42) lower for subjects with sensitization compared with nonsensitized subjects.

Our study suggests that biomarkers of atopy can predict a more favorable long-term response to ICSs. Randomized controlled studies are needed to confirm these findings.