Epidemiology of chronic airway disease: results from a cross-sectional survey in Beijing, China.

Background: Although the epidemiology of chronic airway disease (CAD) has been investigated in several population-based studies, the findings of these studies are diverse. We aimed to investigate the prevalence of CAD and its associated factors in urban northern China. Methods: A cross-sectional study was conducted among 29,359 Chinese adults aged >= 20 years. All participants were randomly recruited from two urban communities in Beijing and asked to complete a self-administered questionnaire that enquired about the demographic characteristics as well as the diagnosis of CAD and CAD-related symptoms. Results: In all, 26,166 participants completed the questionnaire, with the response rate being 89.1%. The prevalence of diagnosed CAD was 9.0% among men and 7.2% among women, with a total prevalence of 8.1%. Furthermore, 11.5% of the investigated subjects had CAD-related symptoms. Women had a lower risk of developing wheezing, cough, dyspnea, and diagnosed CAD than men (P<0.05). The frequency of CAD-related symptoms and diagnosed CAD was greater among elderly persons than among those who were younger (P<0.01). Subjects with a smoking habit were more susceptible to CAD-related symptoms and diagnosed CAD (P<0.01). Additionally, individuals with CAD-related symptoms were more likely to be diagnosed with CAD, compared to those without these symptoms (P<0.01). Conclusions: CAD is a common respiratory disease in urban northern China. Female gender might be a protective factor against CAD, while age and smoking are risk factors for the disease.