COPD Risk Factor Profiles in General Population and Referred Patients: Potential Etiotypes.

Purpose: To identify the risk factors for chronic obstructive pulmonary disease (COPD) in view of potential etiotypes in a general population and referred COPD patients. Patients and Methods: We performed a cross-sectional observational study utilizing two distinct datasets: a dataset of a general population including 2430 subjects with COPD from the Korea National Health and Nutrition Examination Survey (KNHANES) and another dataset of referral clinics including 579 patients with COPD from the Korean Obstructive Lung Disease (KOLD). Results: The mean age of both groups was 67 years, and 71.2% and 93.8% were male in the COPD subjects from the KNHANES and the KOLD, respectively. The mean forced expiratory volume in 1 second of predicted value was 79.1% (KNHANES) and 55.4% (KOLD). The frequency of risk factors of cigarette smoking (C), infection (I), pollution (P), and asthma (A) was 54.6%, 9.4%, 10.7%, and 7.9%, respectively, in the KNHANES COPD subjects, and 88.4%, 26.6%, 41.6%, and 35.2%, respectively, in the KOLD COPD subjects. Risk factors were unidentified in 32.6% (KNHANES) and 3.1% (KOLD) of COPD subjects. Additionally, 14.1% and 66.2% of subjects with COPD had two or more risk factors in the KNHANES and KOLD, respectively. Conclusion: The profiles of risk factors C, I, P, and A were identified and appeared to be different among the two COPD groups from a general population or referral clinics. In some of the COPD subjects, risk factors were not identified, so we should endeavour to find out unidentified COPD risk factors, especially in the general population.