[An 18-year follow-up study on the risk factors of deaths regarding chronic obstructive pulmonary disease in Xi'an, China].

Objective: To examine risk factors of chronic obstructive pulmonary disease (COPD) deaths in Chinese military elderly men.

Methods: A cohort analytic study was carried out in Xi'an, China. A total of 1268 retired military males aged 55 or older were examined in 1987 and followed for 18 years. Main outcome measures were all causes and COPD deaths.

Results: The total person-years of follow-up from 1987 until June 2005 was 18 766.28. The mean follow-up time was 14.35 years; A total of 491 had died, with 748 alive and 29 lost of follow-up. COPD was the second cause of death in all deaths (16.90%). Results Univariate analysis of Cox model showed that age, number of smoking cigarettes per day, duration of smoking, negative affairs and existing COPD were risk factors of COPD deaths and the relative risks [95% confidence intervals (CI)] were 1.13 (1.09-1.17), 1.04 (1.02-1.06), 1.03 (1.01-1.04), 1.81 (2.85-6.77) and 4.39 (2.85-6.77) respectively. Data from Multivariate analysis of Cox model showed that age, number of smoking cigarettes per day and existing COPD were risk factors of COPD death with relative risks [95% confidence intervals (CI)] as 1.10 (1.06-1.15), 1.03 (1.01-1.06) and 3.07 (1.90-4.98) respectively. The risks for deaths increased significantly with increasing amount and duration of smoking resulting from all causes and COPD. Compared with current smokers, former smokers had lower risks of total mortality(excess risk reduction of 66.67%).

Conclusion: COPD was the second cause among all deaths in this cohort. Age, number of smoking cigarettes per day and existing COPD were the risk factors of COPD deaths which called for further survey to examine the relationship between quitting smoking and COPD deaths in this cohort.