The Calgary Depression Rating Scale for Schizophrenia: development and interrater reliability of a German version (CDSS-G)

A German version of the Calgary Depression Rating Scale for Schizophrenia ( CDSS-G) approved by the author of the original scale is presented comprisin g a semi-structured interview for 9 items to sensitively and specifically a ssess depression in schizophrenia and related disorders. The process of tra nslation is outlined and the finally derived CDSS-G was investigated with r espect to interrater reliability in three studies. To keep comparability wi th the CDSS source version a standard procedure was used. Two trained rater s jointly assessed ten schizophrenic patients (study I). In a second study, videotapes with the CDSS-G were presented to clinically inexperienced rate rs (study II, N= 14/15) to test the agreement on the CDSS-G in this sample. Finally, in a third study clinically experienced researchers participated in a rater training (study III, N = 34). They carried out CDSS ratings on t hree patients with mild depressive symptoms. The dependence of interrater r eliability on depression severity was investigated for all studied patients . Both intraclass correlation coefficients (ICC)and weighted kappa coeffici ents (K-W) were calculated. The results revealed a high ICC = 0.97 in study I for the total CDSS-G score. Single item ICC values were all above 0.70, The results of study II revealed somewhat lower agreement on CDSS-G items a nd total scores in psychiatric novices with however acceptable values of K- W > 0.50 for the total Scores. Study III yielded satisfactory results (0.66 < K-W < 0.76) for clinically experienced psychiatrists in schizophrenic pa tients with mild depression. The results demonstrate adequate to excellent interrater reliability of the CDSS-G corroborating the results of the origi nal version in different settings. (C) 1999 Elsevier Science Ltd. All right s reserved.