Psychometric Properties of the Patient Health Questionnaire (PHQ-9) as a Depression Screening Tool for Bariatric Surgery Candidates

BackgroundMajor depressive disorder has been shown in some studies to attenuate weight loss and psychosocial outcomes following surgery. Given the potential implications of depression on surgery outcomes, presurgery psychiatric assessment is recommended to assess suitability for bariatric surgery.ObjectivesThe purpose of this study was to examine the accuracy of the Patient Health Questionnaire-9 (PHQ-9) in detecting depression in bariatric surgery candidates.MethodsBariatric surgery candidates (n = 244) completed the PHQ-9 and the Mini International Neuropsychiatric Interview (MINI) as part of their presurgery psychiatric assessment. The operating characteristics of the PHQ-9 were examined. The study was replicated in an independent sample of bariatric surgery candidates (n = 275).ResultsRates of current and lifetime major depressive episodes were 1.6% to 3.8% and 33.8% to 35.5%, respectively, as assessed by the MINI. According to the PHQ-9, 52.5% to 54.9% of patients exceeded the cutoff for moderate depression (PHQ-9 ≥ 10), and 27.6% to 29.1% for moderate severe depression (PHQ-9 ≥ 15). The optimal dichotomization cutoff point on the PHQ-9 was ≥15 in both studies (sensitivity 75%, specificity 75% to 76%).ConclusionsOur results suggest that the PHQ-9 has adequate operating characteristics compared with a criterion standard measure. A PHQ-9 cutoff of 15 is recommended to identify bariatric surgery candidates who may require further assessment of depressive symptoms.