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22-11-2011 | Mental health | Article

CDSS ‘most effective tool’ for assessing depressive symptoms in schizophrenia


Free abstract

MedWire News: The Calgary Depression Scale for Schizophrenia (CDSS) is the most reliable and valid tool for assessing depressive symptoms in patients with schizophrenia, researchers report.

"We recommend… the CDSS in research as well as in daily clinical practice," say Katja Taxis (University of Groningen, the Netherlands) and team.

Writing in the Journal of Affective Disorders, the researchers explain: "Depressive symptoms are highly prevalent (25%) in patients with schizophrenia [and] are associated with a higher burden of disease and more frequent relapses."

But they add that "Currently there is no overview of available depression instruments and their psychometric properties in patients with schizophrenia."

To address this, Taxis et al searched the literature for studies that investigated the reliability and validity of tools used to assess depression in patients with the mental health disorder.

In total, 47 articles reporting on six instruments met criteria for inclusion in the review.

These instruments included the clinician-rated Brief Psychiatric Rating Scale - Depression subscale, Positive and Negative Syndrome Scale - Depression subscale, Hamilton Rating Scale for Depression, Montgomery Asberg Depression Rating Scale and Calgary Depression Scale for Schizophrenia (CDSS), as well as the self-report Beck Depression Inventory.

Analysis of the pooled results revealed that all of the instruments were reliable for assessing depressive symptoms in schizophrenia patients.

However, the CDSS was the most reliable and valid tool for assessing such symptoms.

Specifically, The CDSS was the most accurate instrument for differentiating depressive symptoms from other schizophrenia symptoms (divergent validity). It was also the instrument least likely to misdiagnose depression or fail to spot such symptoms (predictive validity), at a sensitivity of 88% and a specificity of 88% at the optimal cut-off points.

In addition, the CDSS correlated well with other depression instruments (concurrent validity), the researchers note.

Taxis and team conclude: "In most of the reviewed studies the CDSS outperformed other depression instruments in terms of reliability and validity in patients with schizophrenia."

They add: "As self-report is more expedient for the use in routine clinical practice, further research is needed to develop a self-reporting instrument with psychometric properties comparable to the CDSS."

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Mark Cowen

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