Parent-reported compared with researcher-measured child height and weight: impact on body mass index classification in Australian pre-school aged children.

ISSUE ADDRESSED: Parent-reported data may provide a practical and cheap way for estimating young children's weight status. This study aims to compare the validity and reliability of parent-reported height and weight to researcher-measured data for pre-school aged children (aged 2-6 years). METHODS: This was a nested study within a cluster randomised controlled trial (October 2016-April 2017), conducted within 32 Early Childhood Education and Care (ECEC) services across New South Wales, Australia. Parents of children reported on demographics and child height and weight via a survey. For the same child, height and weight data were objectively collected by trained research staff at the service. We calculated mean differences, intra-class correlations, Bland-Altman plots, percentage agreement and Cohen's kappa coefficient (>0.8 = "excellent"; 0.61-0.8 = "good"; 0.41-0.60 = "moderate"; 0.21 and 0.4 = "fair [weak]"; <0.2 = "poor"). RESULTS: Overall, 89 children were included (mean age: 4.7 years; 59.5% female). The mean difference between parent-reported and researcher-measured data were small (BMI z-score: mean difference -0.01 [95% CI: -0.45 to 0.44]). There was "fair/weak" agreement between parent-categorised child BMI compared with researcher-measured data (Cohen's Kappa 0.24 [95% CI: 0.06 to 0.42]). Agreement was poor (Cohen's kappa <0.2) for female children, when reported by fathers or by parents with a BMI > 25 kg/m2 . CONCLUSION: There was "fair/weak" agreement between parent-reported and measured estimates of child weight status. SO WHAT?: Parent's report of weight and height may be a weak indicator of adiposity at the level of individuals however it may be useful for aggregate estimates.