This is the first study that investigates the responsiveness of the Patient Health Questionnaire-9 (PHQ-9), a standard 9-item self-report depression scale, to antidepressant medication. Authors analyzed data from 1,788 depressed outpatients (66.8% women; mean age, 50.3 years), participating in a prospective, open-label, non-interventional, observational study of sertraline. On the 0-27-point PHQ-9 scale, the total sample gained 10.3 points at 12 weeks, corresponding to a standardized effect size of -1.85. With reference to two independent criterion standards, the PHQ-9 change scores were considerably greater in therapy responders than in nonresponders. The PHQ-9 was equally responsive in men and women. Therefore, the PHQ-9 qualifies as a practical tool for gauging response to pharmacological treatment in depressed patients.
