Five-year inhaled, systemic, and total corticosteroid exposure reduction during anti‒interleukin-5 receptor alpha treatment for severe asthma

Background Anti-interleukin-5 receptor alpha (IL-5Rα) therapy for severe asthma has indicated marked reductions in systemic corticosteroid use. However, little is known about the long-term total (inhaled and systemic) corticosteroid exposure. Objective To estimate total corticosteroid exposure reduction and prevalence of corticosteroid remission over 5 years of anti-IL-5Rα therapy for severe asthma. Methods All Danish adults in whom anti-IL-5Rα for severe asthma was initiated during 2016 to 2019 were observed for 5 years. Corticosteroid exposure was assessed annually using national registries, and changes were estimated using mixed models. Corticosteroid remission was defined as no systemic corticosteroid exposure and low-to-moderate daily inhaled corticosteroid doses. Results In total, 253 patients were included (median age 57 years, 51% female). At baseline, 33% were using daily maintenance oral corticosteroids. The year before biologic therapy, median total corticosteroid exposure was 3604 mg (3404, 3803) prednisolone equivalents. In year 1, total corticosteroid exposure was reduced by 25.2% (13.4, 36.9), increasing to a reduction of approximately 45% in years 3 through 5. Systemic corticosteroids accounted for most reductions, with decreases of 32.8% (21.1, 44.6) during the first year and approximately 60% during later years. For inhaled corticosteroids, statistically significant reductions were observed during year 4 at −149.7 µg budesonide equivalents (−13.7, −285.7) and −189.1 µg (−23.2, −355.1) during year 5. During later treatment years, inhaled corticosteroids represented the primary source of corticosteroid exposure. Corticosteroid remission was achieved in an annual average of 23% whereas 5-year sustained corticosteroid remission was achieved in only 2.4%. Conclusion Over 5 years, anti-IL-5Rα treatment significantly reduced total corticosteroid exposure. Reductions were driven by marked reductions in systemic corticosteroid exposure, whereas modest reductions in inhaled corticosteroid exposure were observed.