Prevalence of Patients Eligible for Anti-IL-5 Treatment in a Cohort of Adult-Onset Asthma

Abstract

Background: Antibodies against the IL-5 pathway have been developed for the treatment of late-onset eosinophilic corticosteroid-resistant asthma. However, the prevalence of severe asthma and the proportion of patients who could benefit from such treatment among the general population of asthmatics remain unknown.

Objective: To evaluate the prevalence and characteristics of patients eligible to anti-IL-5 treatment and severe asthma in an unselected cohort of adult-onset asthma.

Methods: Seinäjoki Adult Asthma Study is a 12-year follow-up study of patients with new-onset adult asthma (n = 203). Prevalence was estimated based on information collected at 12-year follow-up visit. Health care use was collected from the whole 12-year follow-up period.

Results: The prevalence of anti-IL-5-treatable patients was 2%, when the following criteria were used: daily use of medium-to-high inhaled corticosteroid (ICS) dose and long-acting β₂-agonist, ≥2 exacerbations/previous year and blood eosinophil count ≥300 cells/μL or fraction of exhaled nitric oxide ≥ 50 ppb. The prevalence of severe asthma, as defined according to European Respiratory Society/American Thoracic Society, was 5.9%, and only 1 patient met criteria for both groups. When compared with anti-IL-5 eligible patients, severe asthmatics were more often current smokers at diagnosis, obese, used higher ICS dose, and had higher blood neutrophils 12 years after diagnosis. Both groups differed from nonsevere asthma by a higher number of all and unplanned respiratory-related visits to health care. Severe asthmatics showed the highest number of hospitalizations.

Conclusions: In a cohort of unselected consecutive patients with adult-onset asthma, 5.9% fulfilled criteria for severe asthma and 2% qualified for anti-IL-5 treatment. Both groups represent a high burden to health care and specifically targeted treatment could lead to lower use of health care at long term.

Keywords: Adult; Adult-onset; Asthma; Benralizumab; Eosinophil; Interleukin-5; Mepolizumab; Prevalence; Reslizumab; Severe.