Obesity in Mexican school-age children ORIGINAL ARTICLE Factors associated with overweight and obesity in Mexican school-age children: Results from the National Nutrition Survey 1999 Bernardo Hernández, DSc,(1) Lucía Cuevas-Nasu, BSc,(2) Teresa Shamah-Levy, BSc,(2) Eric A Monterrubio, BSc,(2) Claudia Ivonne Ramírez-Silva, BSc,(2) Raquel García-Feregrino, BSc,(2) Juan A Rivera, MS, PhD,(2) Jaime Sepúlveda-Amor, MD, DSc.(3) Hernández B, Cuevas-Nasu L, Shamah-Levy T, Hernández B, Cuevas-Nasu L, Shamah-Levy T, Monterrubio EA, Ramírez-Silva CI, Monterrubio EA, Ramírez-Silva CI, García-Feregrino R, Rivera JA, Sepúlveda-Amor J. García-Feregrino R, Rivera JA, Sepúlveda-Amor J. Factors associated with overweight and obesity Factores asociados con sobrepeso y obesidad in Mexican school-age children: en niños mexicanos de edad escolar: Results from the National Nutrition Survey 1999. resultados de la Encuesta Nacional de Nutrición, 1999. Salud Publica Mex 2003;45 suppl 4:S551-S557. Salud Publica Mex 2003;45 supl 4:S551-S557. The English version of this paper is available too at: El texto completo en inglés de este artículo también http://www.insp.mx/salud/index.html está disponible en: http://www.insp.mx/salud/index.html Abstract Resumen Objective. The objective of the study was to measure the Objetivo. Documentar las prevalencias de sobrepeso y prevalence of overweight and obesity in Mexican school- obesidad en niños mexicanos en edad escolar (5 a 11 años age children (5-11 years) in the National Nutrition Survey de edad) obtenidas de la Encuesta Nacional de Nutrición 1999 (NNS-1999). Material and Methods. Overweight en 1999 (ENN-1999). Material y métodos. El sobrepeso and obesity (defined as an excess of adipose tissue in the y la obesidad (definida como un exceso de tejido adiposo body) were evaluated through the Body Mass Index (BMI) en el organismo) se evaluaron a través del Indice de Masa in 10,901 children, using the standard proposed by the In- Corporal (IMC) en 10 901 niños, tomando como patrón de ternational Obesity Task Force. Sociodemographic variables referencia el propuesto por el International Obesity Task were obtained using a questionnaire administered to the Force. Las variables sociodemográficas se obtuvieron a partir children’s mothers. Results. The national prevalence of over- de un cuestionario aplicado a la madre del niño. Resul- weight and obesity was reported to be 19.5%. The highest tados. La prevalencia nacional de sobrepeso y obesidad fue prevalence figures were found in Mexico City (26.6%) and de 19.5%. Las prevalencias más altas se encontraron en la the North region (25.6%). When adjusting by region, rural Ciudad de México (26.6%) y en la región norte (25.6%). Al or urban area, sex, maternal schooling, socioeconomic status, ajustar por región, zona rural o urbana, sexo, escolaridad de indigenous ethnicity and age, the highest prevalences of la madre, nivel socioeconómico, edad e indigenismo, los overweight and obesity were found among girls. The risks mayores riesgos de sobrepeso y obesidad se encontraron of overweight and obesity were positively associated with en niñas; el riesgo de obesidad y sobrepeso se asoció posi- maternal schooling, children’s age and socioeconomic sta- tivamente con la escolaridad de la madre, con el nivel so- tus. Conclusions. Overweight and obesity are prevalent cioeconómico y con la edad de los escolares. Conclusiones. health problems in Mexican school-age children, particular- El sobrepeso y obesidad son problemas de salud de alta ly among girls, and positively associated with socioeconom- prevalencia en niños en edad escolar en México, especial- ic status, age, and maternal schooling. This is a major public mente en niñas, y se asocia positivamente con el nivel so- health problem requiring preventive interventions to avoid cioeconómico, la edad de los escolares y la escolaridad de This survey was conducted with the support from the Secretaría de Salud. (1) Centro de Investigación en Salud Poblacional, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México. (2) Centro de Investigación en Nutrición y Salud, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México. (3) Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México. Received on: August 20, 2002 • Accepted on: September 18, 2003 Address reprint requests to: Dr. Bernardo Hernández, Director de Salud Reproductiva, Instituto Nacional de Salud Pública. Avenida Universidad 655, colonia Santa María Ahuacatitlán 62508 Cuernavaca, Morelos, México. E-mail: [email protected] salud pública de méxico / vol.45, suplemento 4 de 2003 S551 ORIGINAL ARTICLE Hernández B et al future health consequences. The English version of this pa- las madres. Este es un problema de salud pública que re- per is available too at: http://www.insp.mx/salud/index.html quiere acciones de prevención para evitar riesgos en la sa- lud en un futuro. El texto completo en inglés de este artículo también está disponible en: http://www.insp.mx/salud/ index.html Key words: nutritional surveys; body mass index; overweight; Palabras clave: encuestas nutricionales; índice de masa cor- obesity; school-age children; Mexico poral; sobrepeso; obesidad; niños en edad escolar; México besity, defined as an excess of adipose tissue in school-age children, as measured by the National Nu- O the body, is currently considered a public health trition Survey 1999 (NNS-1999). This survey is repre- problem worldwide.1,2-5 In Latin America, the preva- sentative at the country level and includes four regions lence of obesity has greatly increased in all population and urban and rural areas of Mexico. The prevalence groups, particularly in low socioeconomic level popu- of obesity and its association with sociodemographic lations.6-8 Women of reproductive age (12-49 years characteristics are analyzed to generate information old) and children <5 years are two population groups that should be useful for designing nutrition programs with a high prevalence of obesity.9-10 Moreover, some and interventions to prevent obesity. countries have reported an increasing prevalence of obesity in those population groups in the last two de- Material and Methods cades.11-13 In Mexico, several studies have documented a high Population and sample size prevalence of overweight and obesity.9,10,14 The Mexi- co City Urban Food and Nutrition Survey (Encuesta The study population consisted of Mexican school-age Urbana de Alimentación y Nutrición en la Zona Metro- children aged 5-11 years. Data were collected through politana de la Ciudad de México or ENURBAL 1995) the NNS-1999 conducted from October 1998 to March found a prevalence of overweight and obesity of 13.6% 1999 and included a probabilistic sample representa- among children <5 years of age.15 tive of the four regions and urban and rural areas of Childhood obesity is a common nutrition prob- Mexico (population over or under 2 500 inhabitants). lem –and therefore a public health problem– in devel- The study sample was selected from the National oped countries. Obesity statistics are available in Household Sampling Frame (Marco Muestral Nacio- Mexico at the country level for children <5 years of nal de Hogares) of the National Institute of Statistics, age and women of childbearing age.9,10,15 Although the Geography, and Informatics (Instituto Nacional de Es- precise prevalence of obesity in Mexican school-age tadística, Geografía e Informática, INEGI), using a children remains unknown, it is estimated to be high multistage, stratified, cluster sampling design. and is showing an upward trend.16 Available informa- The survey included 21 000 households, from which tion on the prevalence of obesity in school-age chil- 8 200 had a 5- to 11-year-old school-age population dren comes from small studies; for example, in two currently living there. The non-response rate was 7.6% areas of Mexico City the prevalence of overweight and for this population group, leaving a sample of 11 415 obesity among children aged 10-15 years was ap- school-age children. Only school-age children of families proximately 24% in 1998.17 who refused to participate were excluded. Further studies have documented an association between childhood obesity and the risk of adult obe- Study design sity18 as well as the risk of chronic diseases such as hypertension, diabetes (due to hyperinsulinemia), A cross-sectional study was conducted to assess the hypercholesterolemia, cardiovascular disease, and prevalence of overweight and obesity and its associa- cancer.19-22 tion with sociodemographic characteristics in children There is a dearth of information on the nutritional aged 5-11 years. The Body Mass Index (BMI= weight status of the school-age population at the country lev- kg/height m2) was utilized to measure the dependent el. To fill this gap, this paper aims at documenting the variables for overweight and obesity. To classify chil- prevalence of overweight and obesity in Mexican dren as being overweight or obese, we used the age S552 salud pública de méxico / vol.45, suplemento 4 de 2003 Obesity in Mexican school-age children ORIGINAL ARTICLE and sex specific cutoff points proposed by Cole et al, as weight and height values or implausible values were suggested by the International Obesity Task Force.23 checked and corrected. Implausible anthropometric These cutoff points are based on a reference population values were defined as BMI values <10 or >38. The fi- which includes data from different countries, and nal database contained all the study variables and in- generates BMI-specific centiles for children linked to cluded a sample of 10 901 school-age children. adult BMI cutoff points of 25 kg/m2 (overweight) and 30 kg/m2 (obesity). Analysis The independent variables were residence region North (Baja California, Baja California Sur, Coahuila, After exploratory data analysis, crude and adjusted Chihuahua, Durango, Nuevo León, Sonora, Tamau- odds ratios and relative risks with 95% confidence in- lipas), Center (Aguascalientes, Colima, Guanajuato, tervals were obtained, to identify risk factors associat- Jalisco, México (excluding suburban counties of Me- ed with overweight and obesity.