2003, Number 1
Actualización de la Escala de Depresión del Centro de Estudios Epidemiológicos (CES-D). Estudio piloto en una muestra geriátrica mexicana
Reyes-Ortega M, Soto-Hernández AL, Milla-Kegel JG, García-Ramírez A, Hubard-Vignau L, Mendoza-Sánchez H, Mejía-Garza LA, García-Peña MC, Wagner-Echeagaray FA
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Language: Spanish
References: 29
Page: 59-68
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ABSTRACT
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 average; 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 the original CES-D scale, a threshold to identify possible cases of depression was defined using the mean plus one standard deviation. The comparison indicated good to very good concordance between both scales (kappa = 0.79). However, it is important to consider that the revised CES-D includes the original scale plus 15 added items, and this might contribute to the concordance between the two scales. It is interesting to point out that 14 patients who were not classified as possible cases by the original CES-D scale were identified as such by the revised scale. On the other hand, the original scale identified eight patients as possible cases who were not classified as such by the revised scale. In this sample, based upon the revised version of the CES-D scale, four out of ten male or female patients reported depression symptoms. However, important differences by sex were found with respect to the proportion of patients gathered by groups of symptom severity. Among the female patients, 9% and 13% were classified as either having “probable major depressive episode” or with “significant clinical symptoms of major depressive episode”. In contrast, male patients were more frequently classified as having sub-threshold depression (18%) or with a possible major depressive episode (6%).
Discussion. The most important findings of this paper can be summarized as follows. A revision of the original CES-D scale is offered. The revised version of the CES-D reported in this paper has good to excellent internal consistency when administered through face-to-face interviews by trained personnel. The revised scale has adequate validity, suggesting that a functional instrument can be developed to be used in large community surveys, and also as an aid for clinically oriented work. The data gathered in our survey indicates that two out of three patients seeking primary health care do not present depression symptoms that might have clinical significance, whereas one out of eight elderly women might be undergoing a major depressive episode.
Several important limitations of the present study need to be acknowledged. First, the sample was not drawn by random procedures and might not be representative of all elderly patients seeking health care in this family practice unit. Another important limitation is the lack of a clinical appraisal to confirm or refute results from the CES-D. Yet, another limitation is the relatively small sample size of this study, which prevents us from performing further statistical analyses.
In spite of important limitations such as these, our study offers important results. First, the internal consistency of the revised scale across interviewers and groups of age and sex suggests that this new version is at least as reliable as the original CES-D, and these results are consistent with findings reported by Eaton and colleagues in their study done in the US. The study also offers some evidence on the validity of the revised scale, at least in terms of content and construct validity. However, further studies are needed before more solid evidence is available. Directions for future work in this area include studies with clinical assessment depression symptoms to allow for comparison with results from the revised CES-D scale, as well as the need to obtain bigger and more heterogeneous samples to attempt replication of the preliminary findings reported here.
Concepts and reference systems evolve with science and practice. The original CES-D was designed in the early 1970s and it was already out of date with respect to major classification systems such as the DSM-IV. The revised version of the CES-D conforms to DSM-IV criteria for major depressive episode, and as such might be useful both in clinical settings and in epidemiologic studies.
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