Detection of Depression in Acute Schizophrenia: Sensitivity and Specificity of 2 Standard Observer Rating Scales

Abstract

Objective: To compare the psychometric properties of the Calgary Depression Rating Scale (CDRS) and the Hamilton Depression Rating Scale (HDRS) for severity assessment of depression in acute schizophrenia. Method: During clinical routine treatment, we investigated 119 inpatients with acute schizophrenia, using the CDRS, the HDRS, and a global 4-point Depression Severity Scale (DEP-SEV). We compared CDRS and HDRS sum scores regarding their diagnostic accuracy, with global severity of depression as the criterion. We estimated sensitivity and specificity on the basis of receiver operating characteristic curves. Results: According to global clinical ratings (DEP-SEV), 31% of patients had no depression, 19% had mild, 31% had moderate, and 19% had severe depression. Sensitivity was significantly higher ( P < 0.05) for the CDRS than for the HDRS to assess mild (0.94 vs 0.76, cut-off 3 vs 10 points) or severe depression (1.00 vs 0.78, cut-off 11 vs 22 points); specificity was comparably high (≥ 0.88) for both scales. Conclusion: Despite the fact that both scales were effective in separating mild, moderate, and severe depression, significant advantages emerged for the CDRS to detect mild or severe depression in schizophrenia.