The Risk Factors and Characteristics of COPD Among Nonsmokers in Korea: An Analysis of KNHANES IV and V

Purpose: Chronic obstructive pulmonary disease (COPD) is increasing in prevalence and mortality. This study evaluated the prevalence, risk factors, characteristics, and health-related quality of life (HRQoL) of COPD among nonsmokers in Korea. Methods: This was a population-based cross-sectional study using data obtained from the Fourth and Fifth Korean National Health and Nutrition Examination Survey, which was conducted from 2007 to 2011. Results: A total of 15,063 participants completely answered the questionnaire and performed the spirometry. Among them, 59.6 % were nonsmokers and 40.4 % were smokers. The prevalence of nonsmoker COPD was 7.1 %. On multivariate analysis, age ≥65 years (OR, 2.93; 95 % CI, 2.44–3.51), male sex (OR, 2.98; 95 % CI, 2.40–3.71), living in rural area (OR, 1.26; 95 % CI, 1.05–1.51), lower body mass index (BMI) (<18.5 kg/m²) (OR, 3.00; 95 % CI, 1.78–5.01), self-reported asthma (OR, 2.72; 95 % CI, 2.05–3.60), and self-reported tuberculosis (OR, 4.73; 95 % CI, 3.63–6.17) showed a significantly higher risk of nonsmoker COPD. Analysis of nonsmoker and smoker COPD revealed that there are more females in nonsmoker COPD patients (73.9 vs. 6.9 %, P < 0.001). Nonsmoker COPD patients presented with impaired mobility, pain/discomfort, and anxiety/depression functions as well as a lower mean EuroQol Five-Dimension Questionnaire utility score, which showed HRQoL. Conclusions: The burden of nonsmoker COPD was considerable. Older age, male sex, lower BMI, self-reported asthma, and self-reported tuberculosis were risk factors for nonsmoker COPD and there were differences between nonsmoker and smoker COPD in terms of sex, comorbidities, and HRQoL.