The association between body mass index trajectories and cardiometabolic risk in young children

Background Rapid growth is associated with increased cardiometabolic risk (CMR) in adolescence and adulthood. Little is known about whether the association between rapid growth and increased CMR originates in early childhood. Objectives To identify age and sex standardized body mass index (zBMI) trajectories and to examine the association between zBMI trajectories and CMR outcomes in children 0 to 60 months. Study design A longitudinal cohort study was conducted through The Applied Research Group for Kids (TARGet Kids!) in Toronto, Canada. Participants had repeated measures of weight and length or height performed from birth to 60 months of age. Latent class mixed modelling was used to identify the zBMI trajectories. Linear regressions were performed to determine the association between zBMI trajectories and the primary outcome, a CMR score, quantified as the sum of age- and sex- standardized waist circumference, systolic blood pressure, glucose, log-triglycerides and negative high-density lipoprotein cholesterol (HDL-C), divided by root 5. Secondary outcomes were the individual components of the CMR formula as well as diastolic blood pressure and non-HDL-C. Results Four BMI trajectories were identified among the 1166 children. After adjusting for all covariates, children in the rapidly accelerating trajectory had increased total CMR score (beta= 1.38, 95% CI 0.77; 1.99,P< .001) and increased waist circumference score (beta= 2.39, 95% CI 1.92; 2.86,P< .001) compared to the stable low group. Conclusions Rapid growth during early childhood is associated with increased CMR in preschool children, largely driven by larger waist circumference.