Association between pain severity, depression severity, and use of health care services in Japan: Results of a nationwide survey

Background: Depression is often associated with painful physical symptoms. Previous research has seldom assessed the relationship between the severity of physical symptoms and the severity of mental and emotional symptoms of depression or other health outcomes, and no such studies have been conducted previously among individuals with depression in Japan. The aim of this study was to assess the relationship between the severity of physical pain and depression and other outcomes among individuals in Japan diagnosed with depression. Methods: Data for individuals aged 18 and older in Japan who reported being diagnosed with depression and also reported physical pain were obtained from the Japan National Health and Wellness Survey. These respondents were characterized on sociodemographics and health characteristics, and the relationship between ratings of severity on pain in the last week and health outcomes were assessed using bivariate correlations and generalized linear models. Measures included the Patient Health Questionnaire for depression severity, Medical Outcomes Study 12-Item Short Form Survey Instrument for health-related quality of life, the Work Productivity and Activity Impairment for work and activity impairment, and 6-month report of health care use. Results: More severe physical pain in the past week was correlated with more severe depression, worse health-related quality of life, lower health utility, greater impairment at work, and more health care provider visits. These relationships remained significant after incorporating sociodemographics and health characteristics in the statistical models. Conclusion: Individuals whose depression is accompanied by more severe physical pain have a higher burden of illness than those whose depression includes less severe pain, suggesting that even partially ameliorating painful physical symptoms may significantly benefit patients with depression. Clinicians should take the presence and severity of physical pain into account and consider treating both the physical and emotional symptoms of these patients.