Study population
We included 318,950 unique
individuals with asthma during the study period 1999-2018, contributing
with a total of 1,731,632 years of observation time. Demographic
characteristics at time of inclusion including frequency of
asthma-related comorbidities are summarized in Table 1 . The
majority were women (57%) and the median age at cohort entry was 29
years (IQR 20-38 years). The annual asthma cohort from 1999-2018
consisted of 68,799 individuals with active asthma (median, IQR
67,414-70,277), corresponding to an annual asthma prevalence of 3.4%
among 18-45-year-olds in Denmark.