The Reliability and Validity of the Calgary Depression Scale for Schizophrenia

Objective To explore the reliability and validity of the Mandarin version of the Calgary Depression Scale for Schizophrenia (CDSS). Methods 100 healthy controls redid the CDSS in 2 weeks for investigating the re-test reliability; CDSS, Hamilton Depression Scale (HAMD), Positive and Negative Syndrome Scale (PANSS) were evaluated in 150 schizophrenic patients, who were separated into schizophrenia with or without depression group by Structured Clinical Interview for DSM-IV-TR (Research Version, SCID), to explore the internal consistency, split-half reliability, criteria-related validity, convergent and discriminant validity. Results The re-test reliability of CDSS was good (r=0.650, P0.01); the CDSS was found to have high internal consistency (α=0.838, P0.01) and split-half reliability (r=0.857, P0.01). The criteria-related validity was excellent (Z=-5.109, P0.01); the correlation between CDSS and HAMD was significantly positive (r=0.751, P0.01), a weak correlation between CDSS and the PANSS negative and positive subscales was also discovered (r=0.23, P0.05). Conclusions Our findings suggest positive support to Mandarin version of the CDSS; it may be helpful to identify the depressive symptoms in Chinese schizophrenic patients.