Introducción

La prevalencia de los trastornos disociativos (TD) es altamente variable entre países y culturas. Los estudios al respecto documentan prevalencias en el último año que van de 5 a 10% en población general, y de 10.2 a 41.4% en pacientes psiquiátricos. Además, diversos autores sugieren que se trata de entidades frecuentemente infra diagnosticadas, incluso por profesionales de la salud mental. En este estado de cosas, resulta relevante su evaluación en México, con base en un método altamente confiable como las entrevistas psiquiátricas estructuradas y disponer de medidas de tamizaje válidas y confiables para evaluarles de forma breve y sencilla. La Escala de Experiencias Disociativas DES (de las siglas en inglés de Disociative Experiences .Scale) es uno de los instrumentos de auto aplicación más utilizados con este propósito en los estudios realizados en otros países de la orbe. En esta dirección, los objetivos del presente estudio fueron: 1) estimar la prevalencia de TD en una muestra de pacientes psiquiátricos mexicanos con base en la DDIS, una entrevista estructurada para diagnóstico de acuerdo con los criterios de la Asociación Psiquiátrica Norteamericana; y 2) evaluar indicadores de validez y confiabilidad de la versión en español de la Escala de Experiencias Disociativas DES en población mexicana.

Método

La adaptación para México de la DES la hicieron dos expertos en psicopatología con amplia experiencia en clinimetría psiquiátrica, que llegaron a un acuerdo sobre las versiones definitivas tras la discusión de sus versiones independientes. Posteriormente, una psiquiatra previamente capacitada, aplicó la versión en español de la DES y la entrevista estructurada DDIS, a pacientes psiquiátricos del Centro de Atención Integral en Salud Mental de Estancia Breve del Instituto Jalisciense de Salud Mental, de la Secretaría de Salud Jalisco. Todos los sujetos eran mayores de edad, de uno y otro sexo, y aceptaron participar en el estudio de forma anónima y voluntaria.

Resultados

Participaron 100 sujetos, con una edad de 32.43+12.57 años; de los cuales 63 (63%) eran mujeres. El coeficiente alpha de Cronbach de la DES fue de 0.96. Se demostró una diferencia clínica y estadísticamente significativa de las puntuaciones en la DES entre las personas que de acuerdo al DDIS tenían TD, en comparación con las que no lo padecían (grupo con TD: 34.73 + 24.83, grupo sin TD: 10.71+9.64; t=-6.8, gl=98, p<0001); y entre los pacientes con algún TD de acuerdo a la DDIS y un subgrupo con depresión y sin TD (grupo con depresión sin TD: 9.34+8.55; t=6.36, gl=80, p<.0001). Un total de 38 pacientes (38%) cubrió los criterios para algún TD de acuerdo a la DDIS: 24 (24%) para trastorno de identidad disociativa, seis (6%) despersonalización, cinco (5%) amnesia, y tres (3%) para fuga psicógena. El diagnóstico concurrente más frecuentemente documentado en el expediente clínico de aquellos con TD de acuerdo al DDIS fue el de depresión mayor recurrente (n=17;44.7%).

Conclusiones

La prevalencia de TD es congruente con la documentada para muestras de pacientes psiquiátricos en estudios realizados en países occidentales. Empero, resulta francamente superior a la encontrada en culturas orientales, aun en estudios que utilizaron la misma metodología que el presente. Ello pone de manifiesto, una vez más, el papel que juegan las variables psicosociales en la precipitación y/o mantenimiento de los trastornos mentales en general, y de los disociativos en lo particular; y la necesidad de contar con estudios epidemiológicos locales que contribuyan al conocimiento de la problemática de una población específica y a la gestión de servicios de salud mental basados en evidencias de la misma. Además, se aportan pruebas sobre la validez de criterio y la alta consistencia interna de la Escala de Experiencias Disociativas DES en pacientes mexicanos; por lo que se sugiere su uso con fines clínicos y/o de investigación en nuestra población.

Introduction:

Dissociative disorders are characterized by impaired conscious integration functions, personal identity, memory and environment perception. Their frequent psychopathological manifestations are amnesia, depersonalization, fugue states, extra sensorial experiences, trance states and total personality changes.

They usually appear under different life stressors, and their clinical course is highly variable. Prevalence estimates give figures ranging from 5 to 10% among general population, and reach 10.2 to 41.4% among psychiatric populations. This wide variation is one of the indicators of the complexity of this diagnostic entities and of its difficulty to be studied. Culture is a key factor in functionality of subjects with a dissociative disorder, because the acceptance of many of its clinical features varies.

It is accepted that these diagnostic categories are barely-recognized, not only by general physicians, but by experienced mental health specialists.

The original Structured Diagnostic Interviews (SCID, CIDI, SADS, SCAN), did not include them in their widely distributed packages, and many of them decided to create a separate appendix to address them. Unfortunately, structured interviews face an important limitation as there is a lack of trained, and some times, experienced psychopathologist, a fact that difficults to use them in large samples.

Self-report instruments, when they show good reliability and validity, are of great value in terms of time, costs and feasibility. Their major limitation is the low reliability that they show in psychiatric conditions in which lack of insight is present (psychotic disorders).

To evaluate the psychometric properties of translated versions of instruments is highly desirable. This is specially important when elusive disorders are being evaluated.

Given that the cultural environment of Mexico is surrounded by several factors that influence this kind of disorders, the availability of reproducible research instruments is of outmost relevance.

Therefore, the Dissociative Experiences Scale (DES) -the most widely used measure in this field- in contrast with the Dissociative Disorders Interview Schedule (DDIS), was evaluated, with the purpose to give a first approach to a 12 month prevalence of some Dissociative disorders in Mexican psychiatric patients.

Methods:

Subjects:

A non-random, consecutive sample of male and female patients, between 18 and 63 years old were included. They were receiving treatment, regardless of the diagnosis, at the Institute of Mental Health of Jalisco, from the State's Ministry of the Health in Mexico. The ethics committee authorized the study, and they all gave informed consent.

Translation:

The Spanish version of the DES, has a Spanish translation, and a Mexican Spanish idiomatic adaptation was performed by consensus. The DDIS was translated by one bilingual psychiatrist, and independently reviewed by another. Consensus was reached in controverted items. Once a final translated version was obtained, it was given to 10 subjects (mainly with primary school level), to assess item understanding. A second review was performed to reach a culturally compatible version, concentrating in respecting item content validity. Back translation was not considered, because this method does not capture common language of low school population, which is the case of most Mexicans.

Measures:

Dissociative Experiences Scale (DES):

This is a 28 items, self-report scale, designed to evaluate different kinds and severity of Dissociative conditions, in a 0 to 100 range. Most populations without a psychiatric condition or with a non-Dissociative disorder, scored under 20. A cut-off point of 30, usually indicates the possibility of a Dissociative disorder diagnosis. Given that a Spanish version of the DES is available from Spain, only an idiomatic adaptation to Mexican Spanish was performed (changes in slang or word content differences between countries).

Dissociative Disorder Interview Scale (DDIS):

This is a structured diagnostic interview, of 132 yes/no items, designed to assess the presence of DSM-IV Dissociative disorders entities. It is to be applied by mental health professionals, properly trained on its use. It does not give a total score, it assesses each disorder independently. As previous studies performed in different languages, it has adequate psychometric properties, and is the usual golden standard for Dissociative categories. Previous reports on DDIS correlation with DES have shown variations between disorders, with Kappa values for Identity Dissociative Disorder ranging 0.68 to 0.95.

Procedures:

A 4^th year general psychiatry residency doctor was trained in the DDIS, and, after obtaining the patient's consent, applied the DDIS interview, and then gave the patient the DES to be completed. Demographic and clinical variables were obtained, as well as the diagnosis assigned in the patient chart. To analyze results two procedures were planned: 1) compare DES total score punctuation between positive and negative presence of Dissociative disorders according with the DDIS and 2)compare between patients with a Dissociative disorder with or without concomitant major depression.

Results:

A total of 100 subjects were included, 63% female, with a mean age of 32.4±12.5 (range 18 - 63) years old. The DES internal consistency index was 0.96. Patients with a Dissociative Disorder (according to the DDIS), showed clinically and significantly higher DES values than non-Dissociative patients (34.7±24.8 n= 38 vs. 10.7±9.6 n=62; T -6.8, d.f. 98, p< 0.001).

Frequency of Dissociative disorders and symptoms:

Mean DES total score was 19.8±20.6. According to DDIS criteria, 38 subjects fulfilled DSM IV diagnostic criteria for a Dissociative disorder: Dissociative identity disorder 24, Depersonalization Disorder 6, psychogenic fugue 3.

The most common concomitant diagnosis as assessed in the patient chart was unipolar major depression (17 44.7%. When a Dissociative disorder was comorbid with major depression, comparing it with Dissociative disorders only, the difference was greater (34.7±24.2 n= 38, 9.3±8.55, T 6.3, d.f. 80, p<000.1.

Discussion:

Dissociative disorder measurements evaluated, seem to work adequately in Mexican population. Prevalence of dissociative disorders found in this psychiatric population, is consistent with other studies. Further research in the field is needed, to evaluate the influence of cultural factors, including rural and indigenous samples.