Validity of the Patient Health Questionnaire (PHQ)-9 and PHQ-2 in general internal medicine primary care at a Japanese rural hospital: a cross-sectional study ★

ObjectiveTwo depression screening tools, Patient Health Questionnaire (PHQ)-9 and PHQ-2, have not had their validity examined in general internal medicine settings in Japan. We examined the validity of these screening tools.MethodsA total of 598 outpatients of an internal medicine clinic in a rural general hospital were enrolled consecutively and stratified by PHQ-9 score. Seventy-five patients randomly selected and 29 patients whose results from the PHQ-9 were considered to be positive for depressive disorder were then interviewed with a semistructured interview, the Mini International Neuropsychiatric Interview. We calculated diagnostic accuracy of the PHQ-9 and PHQ-2 to detect major depression and that of the suicidality item of the PHQ-9 to detect suicidality using sampling weights with multiple imputations.ResultsSensitivity and specificity for depression were 0.86 and 0.85, respectively, for the PHQ-9 with cutoff points of 4/5, and 0.77 and 0.95, respectively, for the PHQ-2 with cutoff points of 2/3. Sensitivity and specificity of the suicidality item of the PHQ-9 were 0.70 and 0.97, respectively.ConclusionIn internal medicine clinics in Japanese rural hospitals, the PHQ-2 with an optimal cutoff point for each setting plus the suicidality item of the PHQ-9 can be recommended to detect depression without missing suicidality.