Background Real-life evidence on prevalence and management of severe asthma is limited. Nationwide population registries across the Nordic countries provide unique opportunities to describe prevalence and management patterns of severe asthma at population level.

Aim In nationwide register data from Sweden, Norway, and Finland, we examined the prevalence of severe asthma and the proportion of severe asthma patients being managed in specialist care.

Methods This is a cross-sectional study based on the NORdic Dataset for aSThmA Research (NORDSTAR) research collaboration platform. We identified patients with severe asthma in adults (≥18 years) and in children (6–17 years) in 2018 according to the ERS/ATS definition. Patients managed in specialist care were those with an asthma-related specialist outpatient contact (only available in Sweden and Finland).

Results Overall, we identified 598 242 patients with current asthma in Sweden, Norway, and Finland in 2018. Among those, the prevalence of severe asthma was 3.5%, 5.4% and 5.2% in adults and 0.4%, 1.0%, and 0.3% in children in Sweden, Norway, and Finland, respectively. In Sweden and Finland, 37% and 40% of adult patients with severe asthma and ≥2 exacerbations were managed in specialist care; in children the numbers were 56% and 41%, respectively.

Conclusion In three Nordic countries, population-based nationwide data demonstrated similar prevalence of severe asthma. In children, severe asthma was a rare condition. Notably, a large proportion of patients with severe asthma was not managed by a respiratory specialist, suggesting the need for increased recognition of severe asthma in primary care.