Clinical characteristics and related risk factors of depression in patients with early COPD

Background and objective: Although depression is considered one of the comorbidities of COPD, the clinical characteristics of depression in patients with early COPD remain unknown. We aimed to use national-level data to identify the clinical features and risk factors of depression in patients with early COPD. Methods: We examined 7,550 subjects who were registered in the Korean National Health and Nutrition Examination Survey database of 2014 because that was the only year in which the Patient Health Questionnaire-9 for depression status was administered. Spirometry was used to identify patients with COPD whose forced expiratory volume in 1 second was 50% or more, and these patients were included in the analysis. Results: Of the 211 subjects with early COPD, 14.2% also had depression, whereas 85.8% did not. The patients with depression were predominantly living alone and had a greater prevalence of diabetes compared with the patients without depression. The overall quality of life of the subjects with depression was lower than that of those without depression, and only the quality of life index correlated significantly with depression severity. In the multivariate regression analysis, female sex (adjusted OR, 1.79; 95% CI, 1.38–2.31; p,0.01), living alone (adjusted OR, 1.86; 95% CI, 1.37–2.51; p,0.01), and low income (adjusted OR, 2.17; 95% CI, 1.55–3.04; p,0.01) were identified as significant risk factors for depression. Conclusion: In patients with early COPD, depression was associated with a low quality of life, and female sex, living alone and low income were significant risk factors for depression.