Camilla Boslev Baarnes,1 Zorana Jovanovic Andersen,2 Anne Tjønneland,3 Charlotte Suppli Ulrik1,4 1Department of Pulmonary Medicine, Hvidovre Hospital, Hvidovre, 2Center for Epidemiology and Screening, Department of Public Health, University of Copenhagen, 3Danish Cancer Society Research Center, 4Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark Background: Incidence and prognosis for severe asthma–COPD overlap is poorly characterized. We investigated incidence and long-term outcome for patients with asthma–COPD overlap compared to asthma and COPD alone. Materials and methods: A total of 57,053 adults (aged 50–64 years) enrolled in the Danish Diet, Cancer, and Health cohort (1993–1997) were followed in the National Patients Registry for admissions for asthma (DJ45–46) and COPD (DJ40–44) and vital status. Asthma–COPD overlap was defined as at least one hospital admission for asthma and one for COPD (different time points), and incident asthma–COPD overlap as at least one of the diagnoses occurring after enrollment into the Diet, Cancer, and Health cohort. Results: A total of 1,845 (3.2%) and 4,037 (7.1%) participants had admissions for asthma and COPD, respectively, with 662 (1.2%) participants with asthma–COPD overlap. Incidence rate of asthma–COPD overlap per 1,000 person-years was higher in women (0.73) than in men (0.54) (P