Objective: The quality-adjusted life year, which is usually calculated from the health utility value, is now a standard measurement used in political decision-making in health. Although depression is the leading cause of decrement in health utility in general population, impact of comorbid depression among cancer patients has not been studied sufficiently. Therefore, this study aimed to measure the impact of depression on cancer patients' health utility score, according to the severity of depression.
Methods: Impact of depression severity (measured by the Patient Health Questionnaire) on health utility score (measured by the EuroQoL-5 scale) was evaluated in a sample of 328 Japanese cancer patients, controlling for performance status, symptom burden, and demographic variables.
Results: The patients with depression had significantly lower health utility value than those without depression (mean decrement = 0.14). Decrements in health utility of 0.13, 0.18, and 0.19 were observed for mild, moderate, and moderately severe to severe level of depression, respectively. The difference was significant between groups. Depression severity was a significant predictor for health utility (standardized coefficient beta = -0.25), which was comparable with physical symptom burden and performance status. Participants' age, gender, cancer stage, and comorbid illness were not significant. The model explained 37.9% of the variance.
Conclusions: Even mild level of depression caused clinically meaningful decrement in health utility value in cancer patients, which was comparable with decrements due to major physical complications of cancer. Influence of depression should be carefully investigated when interpreting the quality-adjusted life year among cancer patients. Copyright © 2015 John Wiley & Sons, Ltd.
Keywords: DALY; EQ-5D; QALY; cancer; depression; oncology.
Copyright © 2015 John Wiley & Sons, Ltd.