Effect of comorbid depression on health-related quality of life of patients with chronic diseases: A South Korean nationwide study (2007–2015)

Patients with chronic physical diseases often have concomitant depression. Depression influences an individual's health and his or her overall health-related quality of life (HRQoL). The extent to which depression incrementally worsens HRQoL in patients with ≥1 comorbid physical chronic diseases remains unclear. This cross-sectional study is based on data of 50,844 respondents (age, ≥19 years) who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) (2007–2015). HRQoL was measured using the modified EuroQol five-dimensional (EQ-5D) score. Mean HRQoL scores were compared between subgroups of respondents with or without depression. The association between HRQoL and disease status was evaluated using multiple regression models after controlling for sociodemographic variables. HRQoL score decreased when depression was concomitant. HRQoL score of respondents who had ≥3 chronic diseases with concomitant depression (mean = 0.83, SE = 0.010) were significantly lower (p = 0.002) than those of respondents who had ≥3 chronic diseases but no concomitant depression (mean = 0.87, SE = 0.007). Moreover, respondents with ≥3 chronic diseases comorbid with depression showed the largest negative association (coefficient = −0.133, p