Which is the Optimal Depression Rating Scale to Identify DSM-IV Depression in Schizophrenia? A Diagnostic Validity Comparison of Five Mood Scales

Objectives: To find a brief semi-structured or self-report depression rating scale with the highest accuracy for a diagnosis of DSM-IV defined depression in patients with schizophrenia from Iraqi-Kurdistan. Methods: 200 people with schizophrenia living in the Kurdistan Region of Iraq were recruited. The Mini International Neuropsychiatric Interview (MINI) was used to define the presence of schizophrenia; depression was further defined according to DSM-IV criteria. Symptoms of depression were examined using five scales: the Patient Health Questionnaire (PHQ2, PHQ9), Hospital Anxiety and Depression Scale (HADS), the Centre for Epidemiological Studies Depression scale (CES-D) and the Calgary Depression Scale for Schizophrenia (CDSS). Three psychiatrists conducted interviews and rated the Clinical Global Impression (CGI). ROC curve analysis was used to establish the optimal cut-off as well as comparative sensitivity and specificity. Results: Eighty (40%) patients had DSM-IV major depression and 97 (48.5%) had major or minor depression; 157 (78.5%) had at least two DSM-IV symptoms of depression. Comparing the five scales for identification ofdepression showed the optimal methods for detection of major depression (against non-major depression) were the PHQ9 PHQ2 CDSS. Against major depression the PHQ9 was the most accurate method with a sensitivity of 93.8% and a specificity of 84.2%. Optimal methods for detection of major or minor depression (against no depression) were the PHQ2 PHQ9 CDSS. The PHQ2 had a sensitivity of 85.6% and a specificity of 96.1%. Conclusion: Self-report scales, particularly the PHQ2 and PHQ9 appear to perform well against DSM-IV defined depression in schizophrenia. Further validation against non-DSM-IV standards is recommended.