Concurrent physician-diagnosed asthma and chronic obstructive pulmonary disease: A population study of prevalence, incidence and mortality

OBJECTIVE: We conducted a population-based cohort study to estimate trends in prevalence, incidence, and mortality of concurrent physician-diagnosed asthma and chronic obstructive pulmonary disease (COPD). STUDY DESIGN AND SETTING: Two validated health administrative case definitions were used to identify asthma and COPD among all individuals aged 35 years and older living in Ontario, Canada. Annual asthma, COPD, and concurrent asthma and COPD prevalence, incidence, and mortality, standardized for age and sex, were estimated, and compared from 2002 to 2012, using generalized linear models. RESULTS: Standardized prevalence of concurrent asthma and COPD increased by 10.5%, from 2.9% in 2002 to 3.2% in 2012 overall, but more prominently in women compared to men. Overall, standardized incidence decreased by16%, from 2.5 to 2.1 per 1000 individuals, but increased significantly in young adults. All-cause mortality among patients with concurrent asthma and COPD decreased by 11.2%, from 2.6% to 2.2%. Being diagnosed with both diseases was significantly associated with higher all-cause mortality compared to asthma (OR = 1.56, 95% CI: 1.50–1.58), but not compared to COPD (OR = 0.97, 0.96–0.98), except in young adults aged 35 to 49 years where people with asthma and COPD had higher mortality (OR = 1.21, 1.15–1.27). CONCLUSIONS: In a large North American population, the burden of concurrent physician-diagnosed asthma and COPD is increasing, particularly in women and young adults.