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

Background: 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.Objective: 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.Methodology: 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.Results: 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.Conclusions: ACO was a prevalent condition in middle-aged and older Chinese. Better management and more research on ACO are needed.