54 Body Mass Index vs Weight-for-Length in Infancy and Cardiometabolic Outcomes at Age 8-10 Years

Abstract

Abstract Primary Subject area Public Health and Preventive Medicine Background The WHO provides body mass index (BMI) curves for infants 0 to < 2 years old, but how these compare to the recommended method (weight-for-length [WFL]) in predicting later adiposity and cardiometabolic measures is uncertain. Objectives Our project aimed to: 1) confirm that WFL and BMI in infancy are associated with adiposity and cardiometabolic measures at 8-10 years old; and 2) compare the predictive ability of the two methods. We hypothesized that both methods would perform similarly. Design/Methods WFL and BMI Z-scores (zWFL and zBMI) at 6, 12, and 18 months of age were computed using data extracted from health booklets, used among participants in a prospective cohort study investigating the natural history of obesity and cardiovascular risk in youth (n = 464). Outcome measures at 8-10 years included adiposity, lipid profile, blood pressure, and insulin dynamics. The relationships between zWFL, zBMI, and each outcome were estimated using multivariable linear regression models. Outcome prediction at 8-10 years was compared between the two methods, using eta-squared and Lin’s concordance correlation. Results zWFL and zBMI were associated with all measures of adiposity at 8-10 years. Associations with other cardiometabolic measures were less consistent. For both zWFL and zBMI across infancy, eta-squared were highly similar and the Lin’s coefficients were markedly high (> 0.991) for all outcomes. Conclusion zBMI measured in infants appeared to be equivalent to zWFL for predicting adiposity and cardiometabolic measures in childhood. This lends support to the sole use of zBMI for growth monitoring and screening of overweight and obesity from birth to 18 years.