CDSS best for assessing depression symptoms in schizophrenia

By Mark Cowen

Results from a systematic review of published studies suggests that the Calgary Depression Scale for Schizophrenia (CDSS) is the most reliable and valid instrument for assessing depression symptoms in patients with schizophrenia.

Of the six depression instruments assessed, the CDSS most accurately differentiated depressive symptoms from other schizophrenia symptoms, had good correlation with other depression instruments, and was the least likely instrument to miss cases of depression or misdiagnose depression.

The findings come from a review of 48 studies that reported clinician-rated data on the Beck Depression Inventory, the Brief Psychiatric Rating Scale-Depression subscale, the Positive and Negative Syndrome Scale-Depression subscale, the Hamilton Rating Scale for Depression, the Montgomery Asberg Depression Rating Scale, and the CDSS in patients with schizophrenia.

Katja Taxis (University of Groningen, the Netherlands) and team found that all of the instruments were reliable for the measurement of depressive symptoms in patients with schizophrenia.

However, the CDSS had the best divergent validity for negative symptoms and extrapyramidal symptoms, had good concurrent validity (0.77), and the best predictive ability (sensitivity 88%; specificity 88%).

The researchers explain depressive symptoms are common in patients with schizophrenia and are associated with a greater burden of disease and more frequent relapses. But, to date, there has been no overview of available depression instruments and their psychometric properties in patients with schizophrenia.

"We would recommend to use the CDSS for the measurement of depressive symptoms in research and in daily clinical practice of patients with schizophrenia," Taxis and team conclude in the Journal of Affective Disorders.

"The CDSS was most reliable and valid for the measurement of depressive symptoms of schizophrenia."

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