Objective: Evaluation of the reliability and validity of the Hungarian version of the Calgary Depression Scale for Schizophrenics (CDSS) in a Hungarian clinical population of patients with schizophrenia.
Method: One hundred patients diagnosed with schizophrenia according to DSM-IV criteria were included in this study. Patients were all acutely admitted to the psychiatric unit of the Merényi Hospital due to relapse. For evaluating convergent and discriminant validity of the CDSS, scales measuring depression, negative symptoms, extrapyramidal side effects, antipsychotic-induced dysphoria were assessed: Hamilton Depression Rating Scale (HDRS), Positive and Negative Syndrome Scale (PANSS), Subject Well-being under Neuroleptic Treatment (SWN), Drug Induced Extra-Pyramidal Symptoms Scale (DIEPSS), Clinical Global Impressions-Severity (CGI-S), Clinical Global Impressions-Improvment (CGI-I). In order to examine the test-retest reliability of the CDSS we conducted a 3 month-follow-up (n=83), during which we applied the same set of scales.
Results: The interrater reliability was high in both the CDSS (ICC= 0.98) and the other scales (ICC= 0.75-0.98). Measures of internal consistency showed strong reliability, Cronbach alfa was 0.87, Guttman split-half reliabilty was 0.82. Correlation calculations between CDSS and HAM-D resulted in high correlation: r=0.75-0.81. CDSS showed lower correlations with PANSS-N, DIEPSS and SWN, indicating that this scale is able to separate symptoms of depression from negative symptoms, extrapyramidal side-effects and antipsychotic-induced dysphoria.
Conclusion: The Hungarian version of CDSS can be used to assess depression in schizophrenia and we recommend the introduction of the scale into practice in Hungary.