Asthma-chronic obstructive pulmonary disease overlap in China: prevalence, associated factors and comorbidities in middle-aged and older adults.

Asthma-COPD overlap (ACO) is a persistent airflow limitation with features of both asthma and chronic obstructive pulmonary disease (COPD). No studies have explored the prevalence of ACO at the national level in China. In this study, we aimed to estimate the prevalence of ACO and to assess the associated factors and comorbidities of ACO in middle-aged and older Chinese. Participants aged 45 years and over in a nationally representative investigation - the China Health and Retirement Longitudinal Study (CHARLS) in 2011 - were included. ACO was defined as a dual self-reported physician diagnosis of asthma and COPD. The prevalence of ACO was demonstrated across different characteristic groups. The potentially associated factors and comorbidities were examined by logistic regressions. The prevalence of ACO was 2.22% in general middle-aged and older Chinese. The relative prevalence of ACO to asthma was 62.53% and that to COPD was 21.99%. Older age (≥70 years), Northwest China residence, smoking (former and current) and former alcohol drinking were associated with a higher risk of ACO. Comorbidities of ACO included stomach or other digestive disease, kidney disease, cardiovascular disease, and arthritis or rheumatism. ACO was a prevalent condition in middle-aged and older Chinese. Better management and more research on ACO are needed.