Ron Goldberg
Severe asthma exacerbation rates vary significantly between similar patients with severe asthma residing in different countries, according to study findings published in Chest.
Investigators sought to evaluate the degree of explained and unexplained variation in severe asthma exacerbation rates across countries, primarily in patients with severe asthma who are biologic-naïve.
The study included data from the International Severe Asthma Registry (ISAR), collected between 2015 and 2021, for 7510 patients at least 18 years of age with severe asthma who did not initiate biologics prior to their baseline visit. The ISAR is a prospective observational international cohort of patients from 19 countries (17 countries in the current study; 56% of participants from the United States) who have a clinical diagnosis of severe, uncontrolled asthma. Data are collected using electronic report forms and medical charts.
The rate of severe exacerbations from baseline to 1 year was the primary outcome. Follow-up was to 1 year, and patients with less than 30 days follow-up or with missing visit dates were excluded, as were countries with sample sizes less than 5.
The investigators defined severe exacerbation as oral corticosteroid use for at least 3 days or asthma-related emergency room visit or hospitalization. An intention-to-treat approach was used without adjustments for changes in asthma medications or biologics during follow-up (the 8.2% of participants who used biologics during follow-up were excluded in sensitivity analysis). All patients were treated at baseline with medium or high doses of long-acting beta-agonists (LABA) and inhaled corticosteroids.
Follow-up lasted an average of 353 days. Overall, the investigators noted 1939 severe exacerbations, or 0.27 per person-year, with a significant between-country variation in rate. The minimum per person-year exacerbation rate of 0.04 was found in Argentina and the maximum of 0.88 was in Saudi Arabia (interquartile range [IQR], 0.13-0.39). Second lowest rate was in Colombia (0.08) and second highest was in the United Kingdom (0.76). After adjustment for sampling variability and patient characteristics, the between-country variation remained significant in all covariates (P <.001) except for the long-term use of long-acting muscarinic antagonists (LAMA) and LABA (P >.5).
Study limitations include underestimation of the rate of true exacerbations in countries with limited access to health care, lack of standardized definition of severe asthma across ISAR countries, and the fact that ISAR is not a population-based registry.
“Our findings suggest that each country or jurisdiction adapt clinical recommendations for severe asthma to their setting for optimal treatment escalation strategies,” the study authors concluded. “Moreover, multivariable risk prediction models with setting-specific effects that are properly calibrated to their local settings should be promoted as part of our quest in improving the management of asthma and increasing the efficiency of severe asthma trials.”
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
References:
Lee TY, Price D, Yadav CP, et al. International variation in severe exacerbation rates in patients with severe asthma. Chest. Published online February 21, 2024. doi:10.1016/j.chest.2024.02.029