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

Abstract

BackgroundChronic 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.MethodsThe 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.ResultsAmong 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/m2; OR: 3.1; 95% CI: 1.0–9.4) were associated with the development of COPD.ConclusionLow 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.

Prevalence and Risk Factors of Chronic Obstructive Pulmonary Disease among Nonsmokers: Fifth Korea National Health and Nutrition Examination Survey (2010–2012)

“…The increase in COPD prevalence is similar to findings from the fourth KNHANES (2007–2009) and indicated that the average prevalence in these 3 years was 7.6% [10]. It has been reported that the prevalence of COPD among nonsmoking adults aged ≥ 40 years in China is 5.2% [12], which is slightly lower than the rate in South Korea.…”

“…A study that analyzed 2007–2009 KNHANES data also showed a 4.2-times higher incidence rate in men than in women [10], and a study on Chinese nonsmoking adults showed that the rate was 1.97 times higher in men [11]. Men could be at higher risk due to a lower level of health-related information or a lower rate of practicing health-related behavior than women [10], and are more occupationally and environmentally exposed to hazardous substances [12].…”

“…For the use of the fifth KNHANES raw data, approval was obtained by the Institutional Review Board of the Korea Centers for Disease Control and Prevention (Year 1: 2010-02CON-21-C, Year 2: 2011-02CON-06-C, Year 3: 1201-01EXP-01-2C) [10]. The data were disclosed to the public, and none of personally information of participants were identifiable.…”

“…However, the occurrence of COPD has recently increased among nonsmokers who have never smoked in their lives [9]. There are approximately 50 million nonsmoking COPD patients worldwide [6], and recent reports have revealed that the prevalence of COPD among nonsmoking South Koreans is 7.1–8.2% 10, 11.…”

“…The risks of respiratory infection also vary depending on the rate of practicing health-related activities or the level of occupational exposure to hazardous substances 10, 12. A decreased level of immunity or pulmonary compliance due to increased age may also lead to increased risk of respiratory infections or deterioration of respiratory function [13].…”