Trends in the lifetime risk of COPD exacerbation requiring hospitalisation

This study aimed to estimate time trends in the lifetime risk of hospitalisation with exacerbation of chronic obstructive pulmonary disease (COPD) in Denmark. During the period from 1994 to 2008, a register-based cohort study was conducted covering each subject in the entire population of Denmark (5.18 million in 2008). Based on previously validated diagnosis codes, all COPD hospitalisations were identified. Individual retrospective review periods of 8 years were used to determine first-time hospitalisations. From year 2002 to 2008, all first-time COPD hospitalised subjects aged ≥30 years were identified. The calculation of lifetime risk was based on age- and sex-specific first-time COPD hospitalisation rates and rates of COPD hospitalisation-free survival, assuming them to be calendar time stationary. The study included 23.9 million person-years of risk time and identified 48 959 first-time COPD hospitalisations. For 30-year-olds in Denmark, the lifetime risk of COPD hospitalisation was 12.0% (95% CI 11.9-12.2) for females and 10.9% (95% CI 10.8-11.1) for males. Trends were generally equal in both sexes. During the period from 2002 to 2008, the rate of first-time COPD hospitalisations decreased, while the survival of never COPD hospitalised subjects increased. In consequence, the lifetime risk of COPD hospitalisation remained constant.