Cut points on the Patient Health Questionnaire (PHQ-9) that predict response to cognitive-behavioral treatments for depression

Objective: Monitoring depressive symptoms during treatment can guide clinical decision making and improve outcomes. The aim of this study was to explore values on the Patient Health Questionnaire (PHQ-9) that could predict response to treatment. Method: Data came from two independent trials, including three treatment modalities of cognitive-behavioral treatment for depression. Four hundred eighty-seven participants who either met the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition criteria for major depressive disorder or had PHQ-9 scores consistent with a diagnosis of depression were included in our analyses. Participants either received 18 weeks of telephone or face-to-face (n = 279) or 8 weeks of Web-delivered (n = 208) cognitive-behavioral therapy. Depressive symptoms, evaluated using the PHQ-9, were reported every 4 weeks in the telephone and face-to-face trial and weekly in the Web-delivered intervention trial. Results: Optimal cut points for predicting end-of-treatment response were consistent in both trials. Our results suggested using cut points of a PHQ-9 ≥ 17 at Week 4, and PHQ-9 ≥ 13 at Week 9 and PHQ-9 ≥ 9 at Week 14. Conclusions: Consistent cut points were found within the included trials. These cut points may be valuable for algorithms to support clinical decision making.