Evolución del estado nutricional en una cohorte de escolares chilenos: ¿Un cambio real o ficticio? / Evolution of nutritional status in a cohort of school age children

Background: Considering the high prevalence of obesity among children attending elementary schools, it is important to know the evolution of body weight when these children reach adolescent. Aim: To analyze the changes in nutritional status of children between the first year of elementary school and the first year of high school. Material and methods: A historical cohort of children that were assessed when they started elementary school in 1997 was evaluated again eight years later Weight and height were measured and body mass index (BMI) was calculated. Obesity was considered as a BMI over percentile 95 of Center for Disease Control (CDC) references. The concordance between nutritional assessment in both periods and the risk of obesity during adolescence, based on previous weight were also calculated. Results: Data from 117,815 children were analyzed. The prevalence of obesity in the first year of elementary school and the first year of high school was 14.6 percent and 7 percent, respectively. The mean weight increase during the eight years period was 32.6±8.4 kg corresponding to 108 percent±28.1 percent of the expected increase. There was a low diagnostic concordance between both assessment periods. There was a reduction of under and overweight and a higher proportion of subjects with normal weight in the second assessment period. The risk for being obese in the first year of high school was 6.4 times greater for children that were obese in the first year of elementary school (confidence intervals 6.1-6.9. Conclusions: There was an important reduction in the proportion of obesity between the age of 6 and 14 years. The risk of obesity at 14 years of age was strongly influenced by the presence of obesity at 6 years of age. The broader BMIranges for normality for high school children could give a false image of the nutritional status of teenagers.

Evolución del estado del estado nutricional de escolares chilenos de 6 años (1987- 2003) / Evolution of the nutritional status of six years old Chilean children (1987-2003)

Background: As a consequence of the epidemiological transition in Chile, the nutritional status of the population has changed notoriously. Aim: To study the changes in the nutritional status of six years-old Chilean children from 1987 to 2003. Material and Methods: The computer data base of a government institution in charge of the School Lunch Program (JUNAEB) was used. It contains data on weight, height, sex and date of birth of six years old children, in the years 1987, 1990, 1993, 1996, 2000, 2001, 2002 and 2003. Results: The data of approximately 80,000 children was analyzed. Both weight and height increased over the study years. There was a significant reduction in the number of children with weight deficit but also an increase in the proportion of children with obesity. Stunting was also reduced. The proportion of children with HAZ over 2 SD increased from 0.76 in 1987 to 2.2 percent in 2003. The prevalence of obesity has not increased since the year 2000. Conclusion: The stabilization in the prevalence of obesity is a positive finding, considering its adverse consequences for health.