Drug use in Mexico has been on the rise since the 1970s. Nonetheless, this problem has exhibited important variations in the different regions of Mexico. To document these trends, the National Institute of Psychiatry Ramón de la Fuente (INP) has performed household surveys on addictions in different Mexican cities. In the 1970s and early 1980s surveys were conducted in the following cities: Mexico City, La Paz, Baja California Sur; Mexicali, Baja California Norte; Monterrey, Nuevo León; San Luis Potosí, San Luis Potosí; and Puebla, Puebla, among others. The first national survey in urban population was carried out in 1 988, and was repeated in 1993 and 1998, while the first national survey to included rural population was conducted in 2002, which is being followed by another study currently in the field. The student population has also been extensively studied, and has been included in three national drug surveys and studies performed in different entities. Antecedents Results from these surveys show that drug use has not increased in a uniform fashion throughout the Mexican Republic and both student and household surveys have demonstrated higher rates in the northwestern region of the country comprising the states of Baja California, Sonora and Chihuahua, which have exhibited above-average drug use on comparison with the remaining regions of the country. The most frequently consumed drug by the population is marihuana. The 1988 national household survey registered a rising prevalence in use of 2.9% in Mexican population aged 12-65 years of individuals who had used drugs at some time during their lifetime; in 1993 this prevalence increased to 3.32% and in 1998 to 4.70%; while in 2002 the percentage demonstrated a slight decrease to 3.48%. In 1988, the second place in drug preferences of the population was inhalants with a prevalence of drug use at some time during their lifetime of 0.76%; by 1993, the second place was occupied by cocaine. Prevalence of use of the latter was 0.33% in 1988; by 1993, cocaine increased to 0.56% and to 1.45% in 1998, presenting a slight decrease in use in 2002 (1.23%). From 1988-2002 non-prescribed medical drugs consumed were found in the third place in population preference. Objective This article compared drug use rates observed in three cities on or near Mexico's northern border with the U. S.: Ciudad Juarez, Chihuahua; Tijuana, Baja California Norte, and Monterrey, Nuevo León, were studied as part of the 1 998 national survey on addictions by selecting independent representative samples of these localities and with a new survey of these entities in 2005. Method The 1998 national survey of addictions was carried out in a representative sample of Mexican urban population (in localities of 2500 inhabitants). Independent samples were drawn from inhabitants living in several cities throughout Mexico. In this article we report the drug-use trends for three of these cities (Ciudad Juarez, Monterrey and Tijuana) by comparing the rates observed in 1998 with the results of a new wave of household surveys conducted in 2005 in the same cities using comparable methodology. Samples in both periods included population 12-65 years of age residing in households. Sample design was stratified by means of the following: several stages with localities (Áreas Geoestadísticas Básicas, AGEBS, its acronym in Spanish, census tracts); blocks of houses within the selected localities; segments of houses within sample blocks, and one individual per household as the selection unit in each stage. Sample size in Tijuana was 466 and 553 in 1998 and 2005, respectively, while sample sizes for Ciudad Juarez were 472 in 1998 and 606 in 2005, and for Monterrey this was 637 in 1998 and 675 in 2005, and the non-response rate was 23% in 1 998 and 20.3% in 2005. Instruments for obtaining information employed in both time frames considered were similar. Two types of questionnaires were administered: a household questionnaire that included sociodemographic information on all household inhabitants in the sample and their housing conditions and an standardized individual questionnaire administered in a face-to-face interview that collected information on the following: prevalence and use patterns of tobacco, alcohol, five types of illegal drugs (marihuana, cocaine, heroin, hallucinogens, amphetamine-type stimulants and other drugs); four types of medical pharmaceuticals utilized without a prescription (narcotics, stimulants, tranquilizers and sedatives), determining consequences and services utilization. In this article tobacco and alcohol use is not reported. This questionnaire has been extensively tested and used in previous surveys. Interviewers were persons academically prepared in the Social Sciences and trained in the logistics of the several survey stages and extensively supervised during field work. Results Highest rates of use were observed in Tijuana and Ciudad Juarez in contrast with Monterrey, which had lower rates. When use of any drug was considered, an increase in lifetime use from 1998-2005 was observed in all three cities; when use during the past year was contemplated, an increase was observed from 1998-2005 from 2.8-4.8% in the case of Ciudad Juarez and in Monterrey from 1.3%-2.0%, while these rates for Tijuana decreased from 5.4%-4.01%. Reports of use during the previous month fell in Tijuana from 4.4%-2.81 % and in Monterrey this decreased from 1.1 %-0.71 %, while in Ciudad Juarez drug use rates during the previous month increased from 2.4%-3.24%. It is important to mention that there was no statistical significance in any of the different prevalences types. Lifetime use of medical drugs without prescription increased in Tijuana and in Monterrey, while in Ciudad Juarez this remained stable from 1998-2005. In 2005, use of medical drugs decreased in Ciudad Juarez from 1.2%-0.88% and in Tijuana from 1.3%-1 .28%, while in Monterrey no use was detected in 1998, but 0.48% of interviewees did reported drug use in 2005. Previous-month use increased in Tijuana from 0.7%-1 .28% and in Monterrey this ranged from no use in 1998 to 0.48% by contrast in Ciudad Juarez previous-month drug use fell from 1.2-0.88%. In referring only to use of any illegal drug (excluding medical pharmaceutical), lifetime use increased in all three cities from 1998-2005; lifetime use doubled in Monterrey and Ciudad Juarez, while use during the previous year decreased in Tijuana from 4.4%-3.25% and increased in Ciudad Juarez from 1.6%-3.98% and in Monterrey from 1.3%-1 .52%. Prior-month increased in Ciudad Juarez from 1.2%-2.42%, while this exhibited a decrease in Tijuana from 3.9%-2.05% and in Monterrey from 1.1%-0.23%. Data also indicate that a high proportion of individuals in Monterrey have used only one drug; these percentages rose in the 1998-2005 period from 3.7%-8.96% numbers of the poly-drug users doubled in Tijuana from 4%-8.44% and in Ciudad Juarez from 3.2%-7.43%; in Tijuana this was due to an increase among males, and in Ciudad Juarez the number of poly-drug users increased in both genders.
El consumo de drogas en México ha ido en aumento. En la década de 1970, el Instituto Nacional de Psiquiatría realizó las primeras encuestas de hogares sobre el tema de las adicciones en población de distintas ciudades del país: la Ciudad de México, La Paz, B.C.S.; Mexicali, B.C.; Monterrey, N.L.; San Luis Potosí, S.L.P., y Puebla, Pue, entre otras y ha documentado las tendencias del problema y sus variaciones regionales. A nivel nacional se han realizado en hogares cuatro encuestas en 1988, en 1993, en 1998 y en 2002, denominadas <<Encuestas Nacionales de Adicciones>>. Asimismo se han levantado tres encuestas nacionales sobre drogas entre la población estudiantil, las cuales han dado cuenta de que el consumo de drogas no se ha incrementado de manera uniforme en el país, sino que tanto en las encuestas estudiantiles como entre las de adicciones ha resaltado la zona noroccidental, conformada por estados como Baja California, Sonora y Chihuahua, donde se tienen las mayores cifras de consumo de drogas en la República Mexicana. Las encuestas de adicciones indican que la droga que más ha consumido alguna vez en la vida la población urbana de 12 a 65 años es la mariguana, con los siguientes porcentajes: en 1988, 2.99%; en 1993, 3.32%; en 1998, 4.70%; y en la medición de 2002 disminuyó ligeramente a 3.48%. En 1988, el segundo lugar lo ocupaban los inhalables con 0.76%, pero en las demás mediciones ocupa este lugar la cocaína, con 0.56% en 1 993; 1.45% en 1998 y en 2002, 1.23%. En el tercer lugar se encuentran las drogas médicas consumidas sin prescripción desde 1988 hasta 2002. Este artículo presenta una comparación de las prevalencias de uso de drogas en tres ciudades de la Encuesta Nacional de Adicciones de 1998 con respecto a la Encuesta de ciudades de 2005 de las tres ciudades siguientes: Ciudad Juárez, Monterrey y Tijuana. La Encuesta Nacional de Adicciones de 1998 se realizó en una muestra representativa de la población urbana de todo el país (en localidades de más de 2500 habitantes). En esta encuesta, las 32 entidades del país se dividieron en tres regiones y también se obtuvieron muestras en ciudades fronterizas que fueron: Tijuana, Ciudad Juárez y Matamoros y en tres zonas metropolitanas que fueron: La ciudad de México, Guadalajara y Monterrey. La muestra fue de 12015 entrevistas completas. La encuesta de ciudades de 2005 se realizó en cuatro ciudades que fueron: Querétaro, Monterrey, Ciudad Juárez y Tijuana. Sin embargo, para efectos de este trabajo, solamente se comparan las tres últimas. Las dos encuestas tuvieron como objetivo a la población de 12 a 65 años de edad. En ambas se aplicaron dos cuestionarios: el de hogar con datos socioeconómicos y otro individual, cuyas secciones de consumo de drogas fueron iguales. El muestreo en ambas encuestas fue multietápico, probabilístico y estratificado, y en la última etapa se seleccionó a un individuo de cada hogar con un rango de edad de 12 a 65 años. Se obtuvo una no respuesta de 23% en 1998 y de 20.3% en 2005.
