Prevalence of chronic obstructive pulmonary disease in Korea: The fourth Korean National Health and Nutrition Examination Survey, 2008

Background and objective: Because the mortality and social burden associated with COPD is increasing, repeated surveys of the prevalence of COPD have been used to assess risk factors, detect potential patients, and establish early diagnoses and management protocols. We report the prevalence of spirometrically detected COPD in Korea in 2008, using data from the fourth Korean National Health and Nutrition Survey. Methods: Using nationwide stratified random sampling, based on the Korean Statistical Office census, 6840 subjects aged >= 19 years underwent spirometry, which was performed by four trained technicians, during 2008. The place of residence, levels of education and income and smoking status, as well as other results from a COPD survey questionnaire were also assessed. Results: Airflow obstruction (FEV1/FVC < 0.7) was detected in 8.8% of subjects aged >= 19 years (11.6% of men and 5.9% of women) and COPD was detected in 13.4% of subjects aged >= 40 years (19.4% of men and 7.9% of women). Of the 6840 subjects, 27.3% were current smokers and 17.2% were former smokers, and the prevalence of COPD was higher in current and former smokers than in never smokers. Approximately 94% of patients with COPD had mild-to-moderate disease, without apparent symptoms; only 2.4% had been diagnosed by a physician and only 2.1% of patients had been treated. The independent risk factors for COPD were smoking, advanced age and male gender. Conclusions: Although the prevalence of COPD in Korea is high, the disease is underdiagnosed and most COPD patients are under-treated.