Clinical Utility of the Patient Health Questionnaire–9 in the Assessment of Major Depression after Broad Spectrum Traumatic Brain Injury

Abstract Objective To determine the predictive validity of the Patient Health Questionnaire–9 (PHQ–9) when screening for symptoms of depression following traumatic brain injury. Design Retrospective analysis of data collected as part of routine clinical outpatient care over a period of 30 months. Participants Persons with mild to severe traumatic brain injury who were referred for neuropsychological evaluation within 1–12 months (N = 137). Interventions Not applicable. Main Outcome Measures PHQ–9 and Minnesota Multiphasic Personality Inventory, Second Edition, Restructured Form (MMPI–2–RF). Results PHQ–9 scores > 10 had a sensitivity of 91.7 and a specificity of 60.2 in predicting a diagnosis of major depression. Correlations between PHQ–9 scores and MMPI–2–RF scales Demoralization (0.64) and Low Positive Emotions (0.48) ranged from large to medium. Premorbid outpatient psychiatric treatment was the most consistent predictor of PHQ–9 elevations as well as final diagnoses of major depression. Conclusions The PHQ–9 has adequate clinical utility as a screening instrument for depression in outpatients with traumatic brain injury. Elevations on this instrument can, however, not be automatically be attributed to neuropathology; especially not in the context of premorbid psychiatric dysfunction. Clinicians should conduct more thorough follow-up assessment in those with highly elevated PHQ–9 scores.