Prevalence of depression among outpatients visiting a general internal medicine polyclinic in rural Japan

Objective: In Europe and the US, primary care has been anticipated in identifying untreated depression. Findings show a high prevalence of depression in such settings. However, the prevalence of depression in an internal medicine clinic in a rural area of Japan, which has a role in primary care, is unclear. Method: The prevalence of depression and comorbid psychiatric disorders among outpatients of an internal medicine clinic in a rural general hospital was measured by a structured interview using the Mini International Neuropsychiatric Interview. Outpatients were recruited consecutively and stratified by Patient Health Questionnaire-9 (PHQ-9) scores. Among 598 outpatients, we interviewed 75 randomly selected patients and 29 whose results of the PHQ-9 were positive. We estimated prevalence of depressive episode using age, sex, physical findings by internal medical doctors and PHQ-9 scores as covariates. Results: The estimated prevalence of major and minor depressive episodes were 7.4% [95% confidence interval (CI): 3.4%-11.4%] and 6.8% (95% CI: 2.6%-10.9%), respectively. Among major depressed patients, 71.4% had current suicidal ideation. Conclusion: Given the high rate of depression and suicidality, identification of depression and collaboration between internal medical doctors in a rural area of Japan and mental health professionals are needed.