Prevalence of COPD by disease severity in men and women in northern Vietnam.

The prevalence of COPD and its risk factor pattern varies between different areas of the world. The aim of this study was to investigate the prevalence of COPD by disease severity in men and women and risk factors for COPD in northern Vietnam. From all 5782 responders to a questionnaire survey, a randomly selected sample of 1500 subjects was invited to a clinical follow-up study. The methods included a structured interview using a modified GA2LEN study questionnaire for registration of symptoms and possible determinants of disease. Spirometry was performed before and after bronchodilation. The age distribution of the sample was 23-72 years. Of 684 subjects attending, 565 completed acceptable spirometric measurements. The prevalence of COPD defined by the GOLD criteria was 7.1%; in men 10.9% and in women 3.9% (p = 0.002). Of those 3.4% had a mild disease, 2.8% a moderate and 0.9% a severe disease. In ages >50 years, 23.5% of men and 6.8% of women had COPD. Among smokers aged >60 years (all men), 47.8% had COPD. None of the women with COPD had been smokers. Increasing age, smoking and male sex were the dominating risk factors, although male sex lost its significance in a multivariate setting. The prevalence of COPD among adults in northern Vietnam was 7.1% and was considerably higher among men than women. The prevalence increased considerably with age. Increasing age and smoking, the latter among men only, were the most important determinants of COPD.