The secular trend in the prevalence of overweight and obesity in the population of primary school children from Ljubljana (Slovenia)

Background: The prevalence of overweight and obesity among children has increased dramatically in recent decades. The survey examined overweight and obesity in the population of boys and girls from Ljubljana, the capital of Slovenia, aged seven through fourteen from 1991 to 2011.

Methods: An annually repeated cross-sectional study of data from the national SLOFIT monitoring system was used. The body mass index cut-off points of the International Obesity Task Force were used to identify the prevalence of overweight and obesity. Multinomial logistic regression was used for modelling the probability of overweight and obesity as a function of time (year of measurement), sex and age of subjects.

Results: In 1991-2011 period, the odds for overweight and obesity among primary school children (n = 376,719) increased every year by 1.7% (95% CI: 1.6-1.9) and 3.7% (3.4-4%) respectively. Boys have 1.17 (95% CI: 1.15-1.20) times higher odds of becoming overweight and 1.39 (95% CI: 1.35-1.44) times higher odds of becoming obese than girls. In comparison to the reference group (age of 14), the highest odds for overweight were found at the ages of nine and ten (1.39; 95% CI: 1.34-1.44), while for the obesity the highest odds were at the age of eight (2.01; 95% CI: 1.86-2.16).

Conclusion: From 1991 to 2011, overweight and obesity clearly became more prevalent in children from Ljubljana. This trend has been more obvious among boys than girls. In comparison to 14-year-old boys and girls, the highest odds for excessive weight were found below the age of 10.