Background and purpose: The purpose of this study was to examine the performance of the Patient Health Questionnaire (PHQ)-9, a 9-item depression scale, as a screening and diagnostic instrument for assessing depression in stroke survivors.
Methods: As part of a randomized treatment trial for poststroke depression (PSD), subjects with and without PSD completed the PHQ-9, a 9-item summed scale, with scores ranging from 0 (no depressive symptoms) to 27 (all symptoms occurring daily). Subjects endorsing 2 or more symptoms of depression were administered the criterion standard Structured Clinical Interview for Depression (SCID). Receiver operating characteristic analysis was used to examine the sensitivity and specificity of the PHQ-9
Results: Of 316 subjects enrolled, 145 met SCID criteria for major depression or other depressive disorder, and 171 were not depressed. PHQ-9 scores discriminated well between subjects with any versus no depressive disorder, with an area under the curve (AUC) of 0.96, as well as between subjects with and without major depression (AUC=0.96). The AUC was similar regardless of patient age, gender, or ethnicity. A PHQ-9 score > or =10 had 91% sensitivity and 89% specificity for major depression, and 78% sensitivity and 96% specificity for any depression diagnosis.
Conclusions: The PHQ-9 performs well as a brief screener for PSD with operating characteristics similar or superior to other depression measures and similar to its characteristics in a primary care population. Moreover, PHQ-9 scores discriminate equally well between those with and without PSD regardless of age, gender, or ethnicity.