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

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.