Validity of anthropometric measurements, BMI and child growth assessments conducted by Head Start teachers: training needs for longitudinal child growth surveillance

Abstract

BackgroundHigh prevalence of childhood obesity and associated diseases have been observed in the US Affiliated Pacific but no system for monitoring young child obesity in the region is available. Head Start (HS) preschools located throughout the region complete bi‐annual growth assessments to assess childhood obesity and can potentially contribute to a growth monitoring system.ObjectiveTo assess the relative validity of HS anthropometric measurements and growth assessments for potential use in a surveillance system.MethodsThis was a validation study of HS child anthropometric measurements taken by HS teachers against standardized researcher measurements for height and weight. Data from 19 HS classrooms (135 children) that were previously enrolled in a larger randomized control trial were included in this study. Differences in height, weight, BMI and CDC BMI categories between HS teachers and a standardized researcher were analyzed using paired t‐tests, controlling for child age at time of measurement to quantify differences in HS and researcher measured heights and weights. weighted Kappa statistics determined agreement between the methods on BMI weight categories adjusting for age at measurement with post‐hoc paired t‐tests to analyze differences in BMI categories by measurement method.ResultsHS teacher growth assessments did not significantly differ from those of a standardized researcher and weighted Kappa statistics for agreement based on CDC BMI categories showed reasonable agreement between the two methods (weighted kappa=0.72).ConclusionsAt the programmatic level, this level of agreement suggests that HS measurements are adequate for determining prevalence of BMI categories. However, they may not provide sufficient precision to assess changes over time in individuals and research studies (ie: measuring intervention or program effect). Anthropometric data from HS centers may contribute to a system for childhood overweight and obesity surveillance in the US Affiliated Pacific, however, further training on conducting measurements would be necessary to track individual changes over time.Support or Funding InformationThis project is supported by the Agriculture and Food Research Initiative Grant no. 2011‐68001‐30335 from the USDA National Institute of Food and Agricultural Science Enhancement Coordinated Agricultural Program