Chronic obstructive pulmonary disease in the absence of chronic bronchitis in China: COPD without chronic bronchitis

Background and objective: COPD has a variable natural history and not all individuals follow the same course. The aim of this study was to assess the prevalence of COPD in the absence of chronic bronchitis (CB) based on a population survey in China, and to identify the determinants of CB in patients with COPD. Methods: Amulti-stage cluster sampling strategy was used to survey a population from seven different provinces/cities of China. All residents over 40 years of age were interviewed using a standardized questionnaire and spirometry was measured. A post-bronchodilator FEV1/FVC < 70% was defined as the diagnostic criterion for COPD. All COPD patients who were screened were divided into two groups according to the presence or absence of CB. Results: Of the population of 20 245 that was surveyed, 70% of the 1668 patients who were diagnosed with COPD reported no history of CB. The ages, BMI and comorbidities of COPD patients with or without CB were similar. Male gender, residence in a rural area, having a lower level of education, exposure to tobacco smoke or biomass fuels, poor ventilation in the kitchen and a family history of respiratory disease were all associated with a higher risk of COPD with CB. Patients without CB had less difficulty in walking and higher FEV1/FVC values than patients with CB, but were more likely to be underdiagnosed. The strongest predictors of CB were male gender, current smoking and severity of dyspnoea. Conclusions: This survey confirmed that there is a high prevalence of COPD in the absence of CB in China. It appears that CB is not essential to the diagnosis of COPD.