Background. Body mass index (BMI) screenings in schools are a useful tool in tracking the prevalence of childhood obesity in a population. Following children over time, provides a longitudinal assessment of their body weight status.
Objective. To determine the incidence and track childhood overweight and obesity in children measured in kindergarten and third grade.
Sample. Eight hundred and fifty one children who attended urban, inner-city public school (Cincinnati). The sample included a near equal distribution of boys and girls, was 60% African American and 65% of the children attended schools with low participation in National School Lunch Program (<88%).
Design. Longitudinal Study
Methods. Children's weight and height were measured in kindergarten and third grade. BMI and change in BMI were examined. Determinants of BMI (gender, ethnicity, and social economic status) were used for interpretation. SES was defined by the school's participation in the National School Lunch Program (NSLP).
Results. BMI significantly increased beyond expected growth from kindergarten to third grade (p<0.01). Of the children who were obese in kindergarten, 75.5% remained obese in third grade. Obese kindergartners were also nearly 30 times more at risk for developing obesity in third grade versus children who were not obese (OR=28.97; 95% CI: 17.08,49.14). BMI in kindergarten accounted for 53% of the variation of BMI in third grade. The sensitivity and specificity of obesity in kindergarten predicting obesity in third grade was 49% and 97% respectively. African-American children had significantly higher BMIs versus children of other races in both kindergarten and third grade respectively (p=0.001, p<0.001). Children who attended schools with high participation in NSLP had higher BMIs in kindergarten and third grade versus children who attended schools with lower participation (p=0.03), Between kindergarten and third grade, a higher percentage of girls and children of other races including Mexican Americans and Asians became overweight and obese. Experiencing greater than average changes in BMI between kindergarten and third grade was associated with presence of obesity in kindergarten, low SES and gender.
Conclusion. Between kindergarten and third grade, there was a significant increase in BMI, especially in children who were obese in kindergarten, attended a school with high participation in NSLP or female.