Background: Overweight is shown to track (= to maintain a relative position in a distribution) from childhood to adulthood, but is mostly studied in preobesogenic cohorts and in single ethnic groups. Little is known about tracking of thinness by ethnicity.
Objectives: to determine (differences in) tracking of BMI (class) from 3 through 15 years and the prediction of BMI class at 13-15 years of age in contemporary Dutch, Turkish, Moroccan and South Asian children living in the Netherlands.
Methods: Historical cohort of 7625 children, born 1994-1997, with 24,376 measurements of BMI. BMI z-score and BMI class was analysed using universal criteria. South Asian children were also assessed using ethnic specific BMI criteria. Diagnostic odds ratios (OR) and test properties were calculated to estimate the ability of BMI class at 3-4 years to predict BMI class at 13-15 years.
Results: Tracking of thinness between 3 and 15 years was stronger than that of overweight, as indicated by a generally higher diagnostic OR. BMI trajectories between 3 and 15 years of age of thin, normal weight and overweight adolescents were, although significantly different, quite similarly shaped in children of Dutch, Turkish and Moroccan descent. The South Asian BMI trajectory deviated considerably from the other ethnic groups, but the differences disappeared when South Asian specific BMI criteria were applied. A substantial proportion of overweight developed between 5-10 years, after which less children shifted to other BMI classes. A total of 55-78% of children with overweight at 3-4 years retained their overweight at 13-15 years, and 10-20% of 3-4 year olds with thinness remained thin.
Conclusions: In all ethnic groups, overweight and especially thinness highly tracked into adolescence. South Asian children differed from the other ethnic groups when universal BMI criteria were applied, but with South Asian specific BMI criteria tracking patterns became more concordant.