With increasing obesity prevalence in children globally, accurate and practical methods for quantifying body fat are critical for effective monitoring and prevention, particularly in high-risk settings. No population is at higher risk of obesity than Pacific Islanders, including children living in the independent nation of Samoa. We developed and validated sex-specific prediction models for fat mass in Samoan children.
Dual X-ray absorptiometry (DXA) assessments of fat mass and weight, height, circumferences, and skinfolds were obtained from 356 children aged 7–9 years old in the Ola Tuputupua’e “Growing Up” study. Sex-specific models were developed from a randomly selected model development sample (n = 118 females, n = 120 males) using generalized linear regressions. In a validation sample (n = 59 females; n = 59 males), Lin’s concordance and Bland-Altman limits-of-agreement (LoA) of DXA-derived and predicted fat mass from this study and other published models were examined to assess precision and accuracy.
Models to predict fat mass in kilograms were: e^[(−0.0034355 * Age8 − 0.0059041 * Age9 + 1.660441 * ln (Weight (kg))−0.0087281 * Height (cm) + 0.1393258 * ln[Suprailiac (mm)] − 2.661793)] for females and e^[−0.0409724 * Age8 − 0.0549923 * Age9 + 336.8575 * [Weight (kg)]−2 − 22.34261 * ln (Weight (kg)) [Weight (kg)]−1 + 0.0108696 * Abdominal (cm) + 6.811015 * Subscapular (mm)−2 − 8.642559 * ln (Subscapular (mm)) Subscapular (mm)−2 − 1.663095 * Tricep (mm)−1 + 3.849035]for males, where Age8 = Age9 = 0 for children at age 7 years, Age8 = 1 and Age9 = 0 at 8 years, Age8 = 0 and Age9 = 1 at 9 years. Models showed high predictive ability, with substantial concordance (ρC > 0.96), and agreement between DXA-derived and model-predicted fat mass (LoA female = −0.235, 95% CI:−2.924–2.453; male = −0.202, 95% CI:−1.977–1.572). Only one of four existing models, developed in a non-Samoan sample, accurately predicted fat mass among Samoan children.
We developed models that predicted fat mass in Samoans aged 7–9 years old with greater precision and accuracy than the majority of existing models that were tested. Monitoring adiposity in children with these models may inform future obesity prevention and interventions.
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We are very grateful to the children and families who participate, as well as, our partners in the Samoa Ministry of Health, Bureau of Statistics, Ministry of Women, Community, Social Development, and the OLaGA field team (especially Vaimoana Lupematasila Filipo, Maria Siulepa Arorae, Fa’atali Tafunaina, Folla Unasa, Melania Selu, Lupesina Vesi, and Kima Savusa). Thank you to Dr. Hudda for critical advice, which contributed to the final manuscript. The Ola Tuputupua’e study received financial support from the following sources: Yale University (Faculty Funding, David Dull Internship Fund, Jan A.J. Stolwijk Fellowship Fund, Downs International Health Student Travel Fellowship, Thomas C. Barry Travel Fellowship), US National Institutes of Health (NIH) Minority and Health Disparities International Research Training Program (NIMHD T37MD008655), U.S. Fulbright Graduate Student Research Fellowship, Brown University (International Health Institute, Nora Kahn Piore Award, and Framework in Global Health Program), Brown University Population Studies and Training Center which receives funding from the NIH for training (T32 HD007338) and general support (P2C HD041020), and NIH National Lung, Health, Blood Institute for infrastructure support (R01 HL093093 and HL140570). CCC was supported by Yale-Brown Ivy Plus Exchange Program, Ruth L. Kirschstein Predoctoral Individual National Research Service Award (NIH 1F31HL147414), and the Fogarty Global Health Equity Scholars Program (FIC D43TW010540). WJ acknowledges support from the National Institute for Health Research (NIHR) Leicester Biomedical Research Centre, which is a partnership between University Hospitals of Leicester NHS Trust, Loughborough University, and the University of Leicester.
The authors declare no competing interests.
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Choy, C.C., Johnson, W., Duckham, R.L. et al. Prediction of fat mass from anthropometry at ages 7 to 9 years in Samoans: a cross-sectional study in the Ola Tuputupua’e cohort. Eur J Clin Nutr 77, 495–502 (2023). https://doi.org/10.1038/s41430-022-01256-6