Risk factors of chronic obstructive pulmonary disease in patients with chronic bronchitis

Objective To explore the risk factors of chronic obstructive pulmonary disease (COPD) in patients with chronic bronchitis in following-up 8 years. Methods The baseline survey of the study was carried out on 1 999 patients with chronic bronchitis screened out from 67 251 (15 years or more) rural people in 1992. In 2000, 1 114 patients were reexamined by simple random sampling method. Results 869 (78.0% of 1 114 ) with complete data entered analysis of this study. Smoking, and family history of COPD were associated significantly positively with the decrement per capita yearly of FEV 1 (forced expiratory volume in the first second) and/or FEV 1/FVC (forced vital capacity) ratio. Ex-smoking decreased the decrement of lung function in smokers. The accumulative incidence of COPD was associated positively with smoking and family history of COPD and negatively with baseline FEV 1 and FEV 1/FVC. The relative risk of COPD was not significantly different between non-smokers and ex-smokers. Conclusion For Chinese rural patients with chronic bronchitis, aging, smoking, family history of COPD, lower pulmonary function are independent risk factors of COPD while sex is not one. Ex-smoking can almost decrease the relative risk of COPD to the approximative risk level of non-smoking.