Inhaled corticosteroids and FEV1 decline in asthma: an international cohort study

Inhaled corticosteroids (ICS) may prevent lung function decline in asthma but long-term studies are still few. As part of ALEC (EU Horizon 2020 Grant #633212) we assessed the association between ICS use and FEV1 decline in allergic and non-allergic asthma using the ECRHS data. We identified adults with doctor-diagnosed current asthma in 1999–2002 (ECRHS II) and followed them up to 2010–13 (ECRHS III). We analysed annual FEV1 decline in mL/y (ΔFEV1) in relation with ICS use during follow-up (no use, and use for <1.7, 1.7–10, >10 y, based on tertiles). We adjusted for sex, age, height, education, smoking, BMI, ΔBMI, centre (random intercept), and tested effect modification by allergen sensitisation (specific IgE >0.35 kU/L for mite, cat, grass pollen, or Cladosporium). Among 341 subjects with asthma aged 29–55 years, 66% used ICS during follow-up. At baseline, users for >10 y reported more previous hospital/ED admissions (34 vs 4%, p<0.001) and oral corticosteroid use in the last year (12 vs 1%, p=0.001) compared to non-users. ICS use was associated with an increased FEV1 decline among subjects without sensitisation but not in sensitised individuals (Figure 1) (p interaction 0.01). Results were consistent when analysing decline as a % of baseline FEV1 (p interaction <0.001). These preliminary results suggest that a long-term ICS therapy may be more effective in preventing FEV1 decline in allergic compared to non-allergic asthma.