ACTUALIZACIÓN DE LA ESCALA DE DEPRESIÓN DEL CENTRO DE ESTUDIOS EPIDEMIOLÓGICOS (CES-D). ESTUDIO PILOTO EN UNA MUESTRA GERIÁTRICA MEXICANA

SUMMARY Introduction. Depression is one of the leading causes of disease and disability in the world. Yet, most cases of depression are ignored by the community or even at certain levels of the health care system. Thus, medical care is delayed, a fact that has a negative impact on public health and on socioeconomical conditions. In this context, screening instruments for depressive symptoms can help to improve the recognition rates, and therefore to offer adequate treatment. Also, timely referral to appropriate health care may be achieved. The Center for Epidemiologic Studies Depression Scale (CES-D) is one of the instruments most widely used to screen depressive symptoms. The CES-D was created in the early 1970's, long before the current DSM-IV and ICD-10 classification criteria were available and therefore its content do not cover all the criteria included in these contemporary classifications. The present study is meant to be a first attempt to generate a new and revised design for the CES-D, and thus, to count on a reliable, valid, and suitable instrument to be used in the context of large community studies of depression. The revision is based on prior work carried out by Eaton and colleagues. Methods. In order to make a revision of the CES-D used for the Mexican elderly population, it was necessary to translate the revised instrument, to harmonize its items according to our culture and to the construct being measured, and also to adapt the questionnaire for a field-test pilot study. A survey among patients visiting a large primary health care clinic was then carried out (n=300). Because it was impossible to know in advance the number of patients that were seeking services each day, a sample by convenience was used. However, the sample was not influenced by age, sex or physical appearance of the patients. Before the interview actually started, informed consent was obtained from all the participants. The nature and scope of the study, the fact that their freedom to skip any question or to refuse their participation with would not affect their right to receive the services they were expecting. All was explained to each one individually, interviewers received training which included interview techniques and detailed discussions regarding ethical issues. The questionnaire for the survey gathered information on age and sex, and included the revised CES-D scale with 35 items, and the 30 questions listed in the Geriatric Depression Scale. Double, independent data entry was performed using EpiData software. The data were then translated into SPSS format, using the scale's algorithm that was developed by Eaton and colleagues (1988). This algorithm assesses the presence of symptoms according to DSM-IV criteria and sorts respondents into the following groups: "Having significant clinical symptoms of major depressive episode", "probable major depressive episode", "possible major depressive episode", "sub-threshold depression", and "no-symptoms depression with clinical significance". Further analyses were performed using STATA 7.0 version to assess reliability and validity of revised scale. Results. A total of 288 patients were actually interviewed, 191 of whom were females and 97 males. The age range of the sample was 60-92 years with a mean age of 73 years for males and 70 for females. Duration of the interviews was 21 minutes on the ave- rage; most of the interviews were completed within 13 and 30 minutes. In regard to reliability of the revised CES-D, Chronbach's alpha was 0.90, with similar coefficients by groups of age, sex, and by interviewer. Item-total correlation varied between 0.11 and 0.74, with 0.50 as the mean correlation. Factor analysis with main components, indicated a one-factor solution that accounted for 25% of the variance. In order to compare results from the revised version versus