Risk factors for chronic obstructive pulmonary disease among never-smokers in Korea

Background: Chronic obstructive pulmonary disease (COPD) patients include those who have never smoked. However, risk factors other than smoking in never-smokers have not been elucidated sufficiently. This study investigated the risk factors for COPD among never-smokers in Korea using population-based data. Methods: The data were retrieved from the Korean National Health and Nutrition Survey IV conducted from 2007 to 2009. Among subjects aged 40 years or older who underwent appropriate pulmonary function tests, never-smokers not diagnosed with asthma and not showing a restrictive pattern on pulmonary function tests were enrolled. Risk factors of COPD in never-smokers were analyzed using logistic regression models. Results: Among 24,871 participants in the representative Korean cohort, 3,473 never-smokers were enrolled. COPD patients accounted for 7.6% of the never-smokers. In the logistic regression analysis, low education status (odds ratio [OR]: 2.0; 95% confidence interval [CI]: 1.2-3.2), occupational exposure (OR: 2.6; 95% CI: 1.3-5.3), a history of tuberculosis (OR: 4.5; 95% CI: 2.3-8.7), bronchiectasis (OR: 6.0; 95% CI: 1.4-25.4), male sex (OR: 4.2; 95% CI: 2.6-6.7), advanced age (60-69 years vs 40-49 years; OR: 3.8; 95% CI: 2.0-7.0), and being underweight (body mass index <18.5 vs 18.0-24.9 kg/m(2); OR: 3.1; 95% CI: 1.0-9.4) were associated with the development of COPD. Conclusion: Low education status, manual labor, a history of tuberculosis and bronchiectasis, as well as male sex, advanced age and being underweight were risk factors for COPD in Korean never-smokers.