Abstract MP012: Sexual Maturation Independently Contributes to Adiposity Differences between African American and Caucasian Girls

Abstract

Introduction: The prevalence of obesity is higher among African American girls compared to Caucasian girls. However, on average, African American girls also reach puberty earlier. Hypothesis: Sexual maturation affects adiposity differences between African American and Caucasian girls. Methods: The sample included 117 African American and 82 Caucasian girls aged 5–18 years. Waist circumference (cm) was measured in our outpatient clinic. Total body fat (grams) was measured by dual-energy x-ray absorptiometry. Abdominal subcutaneous and visceral adipose tissue mass (SAT and VAT in grams) were measured by magnetic resonance imaging. Abdominal images were obtained between the highest point of the liver and the lower pole of the right kidney. Analyzed slices centered on the lumbar inter-vertebral space (L4-L5), were 4.76 cm apart, and depending on the participant’s stature included 2 slices below and 2–5 slices above the L4-L5 interspace. Sexual maturity (breast development on a scale of 1–5 according to the criteria by Tanner) was determined, either by self-report (ages >9 years) or physician assessment (ages 5–9 years). Results: In linear regression models adjusted for age and race, sexual maturation significantly predicted waist circumference (beta=8.1, 95% CI=5.9 to 10.2), total body fat (beta=6767.2, 95% CI=4935.7 to 8598.8), SAT (beta=1988.4, 95% CI=1383.9 to 2592.9) and VAT (beta=56.6, 95% CI=36.8 to 76.4). African American girls had significantly higher waist circumference (p=0.0089), body fat (p=0.0171), and SAT (p=0.0184) compared to Caucasian girls when controlling for age only, but these ethnic differences attenuated to non-significance when sexual maturation was controlled. In linear regression models adjusted for age, sexual maturation, and body fat, although the race differences (African American compared to Caucasian girls) in SAT and waist circumference were attenuated, VAT was significantly lower (p<.0001). Conclusion: Sexual maturity was a significant independent predictor of adiposity in African American and Caucasian girls. Controlling for sexual maturation attenuated the race difference in waist circumference, body fat, and SAT, whereas the race difference remained in VAT. In conclusion, these results indicate that it is important to consider differences in sexual maturation when evaluating differences in adiposity between African American and Caucasian girls.