Cross-cultural adaptation and validation of the Spanish version of the Calgary Depression Scale for Schizophrenia
Introduction
In the last decade, increasing attention has been paid to the diagnosis and assessment of depression in schizophrenia because of its significance for diagnosis, treatment, and outcome McGlashan and Carpenter, 1976, Koreen et al., 1993, Addington et al., 1998, Birchwood et al., 2000. The occurrence of depression is associated with unfavorable prognosis and highlights the importance of identifying these symptoms Drake and Cotton, 1986, Roy, 1986, Caldwell and Gottesman, 1990. Although frequencies of depression in epidemiological studies ranging from 7% to 75% are reported Bartels and Drake, 1988, Koreen et al., 1993, Siris, 1995b, it is generally accepted that depression occurs in 25% of patients diagnosed as having schizophrenia (Siris, 1995a). However, the identification of depressive symptoms in schizophrenics is difficult and, in practice, there is significant overlap between depressive symptoms, negative symptoms, and extrapyramidal symptoms induced by neuroleptics. An additional problem arises from the fact that the methods normally used to measure depression in patients with schizophrenia were developed for nonpsychotic patients (Siris, 1995a) and do not perform well with schizophrenic patients.
To overcome this problem, Addington et al., 1990, Addington et al., 1992 developed a nine-item structured interview scale known as the Calgary Depression Scale for Schizophrenia (CDSS). The scale is derived from the Hamilton Depression Rating Scale (HDRS) (Hamilton, 1960) and the Present State Examination (PSE) (Wing et al., 1974), and assesses symptoms of depression at any stage of the disease. Validity and reliability studies have shown the ease of its use, adequate unifactorial structure and good internal consistency, high interrater reliability, and satisfactory external validity and specificity Addington et al., 1992, Addington et al., 1993a, Addington et al., 1994. An experienced examiner should develop an adequate reliability after five practice interviews.
The CDSS has been adapted and validated to be used in Mexico (Ortega-Soto et al., 1994), France (Bernard et al., 1998), Brazil (Bressan et al., 1998), Germany (Müller et al., 1999), Japan (Kaneda et al., 2000b), Greece (Kontaxakis et al., 2000), and Denmark (Schuetze et al., 2001). The CDSS scale is now translated into 22 languages and can be downloaded from the web site: http://www.ucalgary.ca/cdss/.
The aim of this study was to test the validity of the Spanish version of the CDSS in identifying depressive episodes in patients with schizophrenia in Spain.
Section snippets
Subjects
Ninety-three subjects with schizophrenia attended at ‘Benito Menni Mental Health Institute’ in Sant Boi del Llobregat, Barcelona (Spain) were included in the study. These patients were recruited from the schizophrenic population either admitted for inpatient care or attended at the outpatient clinics of this mental health hospital between May to December 2000. They all fulfilled DSM-IV (American Psychiatric Association, 1994) diagnostic criteria for schizophrenia, confirmed by the Structured
Results
Of the 93 patients studied (inpatients, n=56; outpatients, n=37), 40% were female and 60% male. The mean age of the patients was 37.2 years (S.D.=10.4 years). A total of 19 patients met DSM-IV criteria for Depressive Disorder Without Other Specification and 10 of them showed five or more items for Major Depressive Episode. Demographic data, clinical characteristics of the study population, and total scores on the various assessment scales expressed as mean (S.D.) values are shown in Table 1.
Discussion
The aim of this study was to present the cross-cultural adaptation of the CDSS in a Spanish population as well to assess the psychometric potential of the Spanish-language version of the CDSS with regard to validity and reliability. A total of 93 schizophrenic patients at different stages of the disease were evaluated for depression, and 20.4% of them fulfilled DSM-IV criteria for Depressive Disorder Without Other Specification and 10.7% for a Major Depressive Episode. These percentages are in
Acknowledgements
We are indebted to Dr. Donald Addington for his authorization and helpful suggestions during the validity study of the CDSS-S, to Dra. Marı́a L. Tiffon and Ramon Sarró for their back-translations into English, and to Marta Pulido for editing the manuscript and editorial assistance. This work was supported by the SENY Foundation and the Catalonian Agency of Health Technology Assessment and Research (SENY-CAHTA Grant 14E/99), Barcelona, Spain.
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