[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 FEV1(forced expiratory volume in the first second) and/or FEV1/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 FEV1 and FEV1/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.