2003, Number 4
Salud Mental 2003; 26 (4)
Prevalencia de trastornos mentales y uso de servicios: Resultados de la Encuesta Nacional de Epidemiología Psiquiátrica en México
Medina-Mora ME, Borges G, Lara MC, Benjet C, Blanco JJ, Fleiz BC, Villatoro VJ, Rojas GE, Zambrano RJ, Casanova RL, Aguilar-Gaxiola S
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ABSTRACT
In 2001, the World Health Organization dedicated it’s Annual Health Report to Mental Health in an effort to put this problems at the core of the global health and development agendas. Along with this initiative, governments were invited to collaborate in the so called WHO 2000 initiative on Mental Health gathering information on the nature and extent of the problem, using the cross culturally validated Diagnostic Interview Schedule, WHOCIDI.This study forms part of this initiative. The paper describes the prevalence of psychiatric disorders, regional variations, socio demographic correlates and service utilization in the Mexican urban population between 18 and 65 years of age from the National Survey on Psychiatric Epidemiology (ENEP for its initials in spanish). It is the first time that such national data are gathered and published for Mexico.
The sample design was probabilistic, stratified and multistage, one individual per household was selected. Information was gathered in two phases (information from the composition of the household and from the individual selected among the eligible members) (18-65 years of age), the target population was non institutionalized inhabitants of households in urban localities of more than 2,500 inhabitants, which represents 72% of the national population. The sample design is a strict probability selection scheme: 200 primary selection units (PSU) selected with probability proportional to a measure of size (PPS); census tract areas (AGEB) serving as PSU; 5 city blocks or listing areas selected with PPS within each selected PSU; 1 compact segment in the neighborhood of 9 housing units (hu’s) selected within each selected listing area; all households within selected hu´s included in survey and 1 eligible respondent selected within each selected household.
The field work was conducted in two stages. During the first phase (September- December 2001) 10,377 households were visited up to 5 times to obtain information either on the household or for the selected interviewer. In order to reduce the non response rate, a second phase was implemented; a systematic probabilistic sub sample of 21 PSUs for Mexico City Metropolitan Area and 40 PSUs in the rest of the country was re-visited. The strategy was to complete up to 10 callbacks (including those already completed in the first round) in each non-response household and in each non-response individual interview. During this re-visit, efforts were concentrated on obtaining data on households with missing informants or refusals, and completing interviews on individuals not located previously or individuals that refused the individual interview in the first phase. No financial incentive was given during any phase of the survey. The fieldwork ended in May 2002 and a total of 5,826 completed interviews were achieved. The response rate, both at the household and at the individual level, takes into consideration the complex survey design and the re-visit process. The weighted response rate at the household level was 91.3%, and the weighted response rate at the individual level was 76.6%. The main reason for non-participation at household was “no one at home” (12.8% of eligible households). Direct refusals were infrequent (5.2%). Main reason for nonparticipation at individual level was “absent in the moment” (7.8% of listed individuals). Direct refusals were infrequent (6.2% of listed individuals).
The instrument is a computer assisted version of the Composite International Diagnostic Interview (CIDI certified version 15; World Health Organization, 2001), a structured diagnostic interview, installed on a laptop and administered face to face by a lay interviewer. The CIDI provides DSM-IV and ICD-10 diagnoses for lifetime, 12-month and 30-day timeframes of 23 disorders as well as modules covering demographics, employment, finances, marriage and children, social networks, family burden, chronic medical conditions, pharmacoepidemiology, disability and service utilization. In this article we present diagnoses according to ICD10.
In order to maximize the yield of information while minimizing the average administration time of the interview some participants answered a long version of the interview and others a short version depending upon participant characteristics, participant responses to screening questions, random selection and household size. Adequate inter rater reliability, test-retest reliability and validity of earlier CIDI versions has been documented. The translation of the instrument into Spanish was carried out according to WHO recommendations. The information was collected by interviewers with previous experienced in systematic data collection extensively trained and supervised during field work. Fifthy four per cent were females, 40% were between 18 and 29 years of age, 68% had completed 6 years of schooling and 12% had a university degree, 67% were married or living with someone, 58% were employed.
Twenty eight point six per cent of the urban adult population of the country meets the criteria for at least one of the 23 disorders considered during their life time, 13.9% during the 12 months previous to the interview and 5.8% during the previous 30 days. Per type of disorder the more frequent were anxiety disorders (14.3% in life time), followed by substance use disorders (tobacco, alcohol and other drugs) (9.2%), and affective disorders (9.1%). When only disorders meeting the criteria for the last 12 months and 30 days were considered, the order was reversed with anxiety and affective disorders being more common than substance abuse and dependence. Males had higher rates of life time disorders (30.4% and 27.1% respectively), but females had higher rates during the last 12 months (14.8% and 12.9%) and during the last 30 days (6.5% and 5.1%). These differences are explained by the higher rates of substance/abuse dependence problems among males and of anxiety and affective disorders among females.
By individual diagnosis, specific phobias were the most common (7.1% in lifetime), followed by behavior disorders (6.1%), alcohol dependence (5.9%), social phobia (4.7%) and major depressive episode (3.3%). Among females phobias (specific and social) followed by major depressive episode were the more common problems while among males alcohol dependence, behavior problems and alcohol abuse (without dependence) were the more common diagnoses observed.
Separation anxiety disorders (median of 5 years) and the attention deficit disorder (median of 6 years) showed the earliest age of onset. Specific phobia (7 years) and oppositionist disorder (8 years) came later. When only diagnosis observed during adult life are considered then anxiety disorders come first, followed by affective and substance abuse disorders.
An additional analysis of periods of onset showed three ages where the initiation of major depressive episodes was more common, around 17 years of age, at 32 and after 60. Results from the study show that affective disorders initiate along all ages of life span. Onset of anxiety disorders tend to concentrate in early ages (before 15 years of age) and substance abuse problems show highest onsets between 15 and 30 years. Most childhood disorders appear between 5 and 15 years, bulimia and adult separation disorder extend during adult life.
The Central West region of the country showed the highest life time prevalence for any disorder, mainly due to the high rate of substance abuse disorders and the South East the lowest rate. Highest 30 day prevalence for affective disorders was observed in the Central West (2.5%), anxiety disorders (3.4%) in the region formed by the 3 metropolitan areas, and substance use disorders (1.7%) in the North.
Service utilization (including formal and informal services) was quite low with only 11.7% of those with at least one diagnosis, 19.4% of those with 2 diagnoses and 11.2% of those with 3 or more. Only 2 of each 30 persons with 3 or more diagnosis received specialized treatment, the most frequent being general doctors.
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