Published online: June 9, 2018
It is recognized that asthma is not a single disease but manifests in many different forms. Novel drugs, antibodies against IL-5 pathway such as mepolizumab, reslizumab, and benralizumab, have been developed for treatment of severe asthma with persistent eosinophilic airway inflammation and poor response to conventional therapy. However, the proportion of patients who could benefit from such treatment among a general asthma population is still unknown.
Ilmarinen et al. investigated the prevalence and characteristics of patients who could benefit from a novel anti-IL-5 treatment, in a report which was published recently in The Journal of Allergy and Clinical Immunology: In Practice. The study was part of the Finnish Seinäjoki Adult Asthma Study (SAAS) and consisted of 203 patients diagnosed with adult-onset asthma. The study cohort included smokers, obese individuals, and patients with multi-morbid disease that are usually excluded from asthma studies. The study had exceptionally long follow-up from diagnosis of asthma and up until the 12-year follow-up visit. Prevalence was estimated based on information collected at year 12. Also, information on healthcare use during the entire follow-up period was included.
The authors found that in the general population of patients with asthma, severe asthma prevalence was 5.9%, and 2% of the patients could benefit from anti-IL-5-treatment. The criteria for eligibility to this novel treatment included daily use of at least medium dose of inhaled corticosteroids and long-acting bronchodilator, at least two exacerbations of asthma during the previous year, and blood eosinophil count ≥300 cells/µl or fractional exhaled nitric oxide (FeNO) at least 50 parts per billion. Anti-IL-5-eligible patients and patients with severe asthma both showed a high number of respiratory-related visits to healthcare, but those with severe asthma were hospitalized more often. The severe asthma patients also differed by being more often smokers at diagnosis and obese 12 years after diagnosis, having higher use of inhaled corticosteroids, and having a different type of inflammation according to blood parameters compared to the anti-IL-5-eligible patients.
Ilmarinen and colleagues summarize that 5.9% of their unselected population of adult-onset asthma had severe asthma and 2% qualified for anti-IL-5 treatment. Both groups represent a high burden to healthcare and specifically targeted treatment could lead to long-term lower use of healthcare.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.