VALIDITY OF THE BDI AS AN INSTRUMENT TO ASSESS DEPRESION IN SCHIZOPHRENIC PATIENTS Pilar Blasco (1) Inma Fuentes (2), Juan Carlos Ruiz (2) and Marisa García Merita (2) (1) Specialized Center for the Mentally Ill in Bétera (CEEM) (2) School of Psychology. University of Valencia. XIII World Congress of Psychiatry. Cairo, September 2005 Depression symptomatology is a highly prevalent condition in patients with schizophrenia, ranging between 7 and 75 percent in the research studies (Gutierrez et al., 2000; Siris, 2000). The depression symptoms most frequently associated with schizophrenia are: sadness, loss of interest in habitual activities, loss of capacity for enjoyment of habitual activities, psychomotor delay, sleep disorders, decrease in the ability to concentrate, weight variation, and death-related thoughts (Apiquian et al., 2001; Chamorro, 1996). This symptomatology has important repercussions on prognosis (a poor response to pharmacological treatment, higher chronicity, and functional deterioration) and direct consequences on the patients quality of life (Apiquian et al., 2001). Furthermore, depression symptoms and feelings of hopelessness are key risk factors associated to suicidal behaviour in schizophrenics. Such suicidal behaviour constitutes one of the most frequent causes of premature death in this population (Barcía y Alcántara, 1999). According to Radomsky et al. (1999), between 20 and 50 percent of patients with schizophrenia will attempt to commit suicide. Within this suicidal group, 48 percent suffer from depressive symptomatology (Baca et al., 2005). This study compare two instruments: one that was specifically developed to be used in schizophrenia, the CDSS (Addington et al., 1990), and one that was not specifically developed for this population, the BDI (Beck et al., 1979). The objective of this comparison is to clarify the following (1) there are differences in prevalence results when different instruments are used to measure depression; (2) instruments specifically developed to measure depression in schizophrenia show lower rates of prevalence. METHOD Participants Thirty two inpatients, who were diagnosed as having schizophrenia according to the DSM-IV, participated in the study. The study took place at the CEEM in Bétera, part of the Social Welfare Department (Conselleria de Bienestar Social) of the Valencian Community. Those patients with any other diagnosis from axis I of the DSM-IV or with mental retardation were excluded from the study. The sample was made up of 18 men (56,25%) and 14 women (43,75%), whose ages ranged from 25 to 54 years old. The majority of participants had a low education level (n=14; 43,75%) or a medium-low education level (n=15; 46,88%). All patients took part in rehabilitation programs (social skills, cognitive skills, integrated psychological therapy for schizophrenia, psycho-education, daily life activities, adult education, vocational workshops, free-time and leisure programs and/or therapeutic outings). Of the total number of patients, % had family antecedents of mental disorder. The time period of evolution of the disease ranged between 9 and 35 years, with an average chronicity of years. The total number of hospital admissions after admission into the CEEM ranged from 0 and 2, with an average of 0.34 admissions. All of the patients were receiving pharmacological treatment with antipsychotics; also, 40.63% of the patients were taking antidyskinetic medication, 75.00% were taking benzodiazepines, and 21.88% were taking antidepressants. Instruments and procedure To assess depression symptomatology, two different tests were administered to the sample: the Beck Depression Inventory (BDI) and the Calgary Depression Scale for Schizophrenia (CDSS). We used the BDI version published by Beck in 1979, which was adapted and translated into Spanish by Vázquez (Vázquez y Jiménez, 2000), and the CDSS version which was adapted and translated into Spanish by Sarró et al. (2004). Both the BDI and the CDSS were filled out using an interview process. The indicators used to signal depression symptoms were the cut-off points established by Beck et al. (1988) and by Bobes (2004) for the BDI and the CDSS, respectively. For the BDI, the direct scoring ranged from 0 to 63 (21 items scored from 0 to 3) and the cut-off point was a direct score that was equal to or greater than 10. For the CDSS, the direct scoring ranged from 0 to 27 (9 items scored from 0 to 3) and the cut-off point was a score of 6 or more, so scores that were equal to or greater than 10 or 6 were considered to be indicators of depression symptoms in the BDI and the CDSS respectively. Table 1. CDSS and BDI scores; Fulfillment of Criterion and the Agreement between the two instruments * 0 indicates that the criterion to determine the existence of depression symptoms is not met; 1 indicates that the criterion is met. ** indicates whether there is agreement between the two scales about the presence or absence of depression symptoms. No indicates that there is no agreement; yes indicates that there is agreement. RESULTS The prevalence of depression symptoms in the sample of patients according to the BDI was 56,25%, and 9,37% according to the CDSS (see Table 1). The total number of coincidences between the two scales with respect to the presence/absence of depression symptoms was 53.12%. In 15 of the cases, BDI rated participants as having depression symptoms, whereas according to CDSS criteria, there were no symptoms. The phi correlation between both scales was calculated after having dichotomized the direct scores of each one, assigning 1 to the cases with depression symptoms and 0 to the remaining cases. The value that was obtained, phi=0,284, was not significant p=0,109. DISCUSSION The results obtained show that 46,88% of the cases that were presented as depression symptoms in the BDI were not interpreted as such by the CDSS. As a consequence, the fact that there is no correlation between the results from the CDSS with the results from the BDI casts doubt on the Beck Depression Inventory as an appropriate assessment tool for depression symptomatology in schizophrenia. These results demonstrate that it is not appropriate to administer scales to populations which the scales were not originally designed for, nor is it appropriate to attempt to obtain information that the scales were not specifically designed to obtain. Thus, when the BDI is used, there appears to be overlap between the symptoms that the scale assesses and the symptoms that are due to other causes, such as specific pharmacological treatments. It must also be noted that the negative symptoms present in schizophrenia cannot be adequately distinguished by tools that were not originally designed to do so, as is the case with the BDI. Even when stricter criterion are used for the BDI – for example, considering the presence of depression symptoms when the authors of the tool already make reference to moderate depression, placing the cut-off point at 16, there still is a large discrepancy between the two scales (28.12%). 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