Overweight and obesity at school entry as predictor of overweight in adolescence in an Arctic child population

Background: The aim of this study was to analyse the changes in the prevalence of overweight, obesity, and in mean body mass index (BMI) among school children, and to analyse the predictive value of overweight and obesity at school entry to overweight and obesity in adolescence in an Arctic child population. Methods: Retrospective cohort study. A database was created on the basis of files from health examinations. Data on children aged 5-7 years and 13-17 years and the subsample of children followed from school entry to adolescence was analysed. Results: During the years 1972-2002 the prevalence of overweight and obesity increased significantly, and mean BMI rose by 5.6% at school entry and by 4.7% in adolescence. Sensitivity and specificity: Of the children being obese in adolescence, 56.3% were already obese at school entry; for the overweight children, 50.6% were also overweight or obese at school entry. Of the children with normal weight in adolescence, 91.9% were also normal weight at school entry. The positive predictive value of being overweight or obese combined at school entry was 59.5%, i.e. more than every second retained their overweight or obesity in adolescence. Only 10% of the obese school entry children had gained normal weight in adolescence. The negative predictive value for normal weight children at school entry was 91.3%. Conclusion: The study showed that during 30 years from 1972, overweight and obesity among school children in Greenland have increased dramatically. Overweight and obesity at school entry were shown to be a good predictor of overweight or obesity in adolescence.