Characterization of severe asthma worldwide: data from the International Severe Asthma Registry (ISAR)

Abstract Background To date, clinical characteristics of the international severe asthma population are unknown. Inter-country comparisons are hindered by variable data collection within regional/national severe asthma registries. Our aim was to describe demographic and clinical characteristics of patients managed in severe asthma services in the USA, Europe, and Asia/Pacific region. Methods The International Severe Asthma Registry (ISAR) retrospectively and prospectively collected data on severe asthma patients (≥18 years old), receiving GINA Step 5 treatment or remaining uncontrolled on GINA Step 4. Baseline demographic and clinical data were collected from the U.S., UK, South Korea, Italy, and the SAWD registry (including Australia, Singapore and New Zealand) from December 2014-December 2017. Results 4,990 patients were included. Average age was 55.0 (SD: 15.9) years, and age at asthma onset 30.7 (SD: 17.7) years. Patients were predominantly female (59.3%), white (72.6%), had never smoked (60.5%) and were over-weight/obese (70.4%). 34.9% were on GINA Step 5. 57.2% had poorly controlled disease. 51.1% of patients were on regular intermittent OCS and 25.4% were on biologics (72.6% for those on GINA Step 5). Mean exacerbation rate was 1.7 (SD: 2.7) per year. Inter-country variation was observed in clinical characteristics, prescribed treatments and biomarker profiles. Conclusions Using a common dataset and definitions, this study is the first to describe severe asthma characteristics of a large cohort of patients included in multiple severe asthma registries, and to identify country differences. Whether these are related to underlying epidemiological, environmental factors, phenotype, asthma management systems, treatment access and/or cultural factors requires further study.