Examining the accuracy of the New Zealand B4 School Check universal health service anthropometric measurements of children.

BACKGROUND:The aim of the current study was to determine whether anthropometric data from the New Zealand B4 School Check (B4SC) universal health service assessments are comparable to research grade anthropometric data. METHODS:B4SC anthropometric data were obtained for a subsample (n=394) of children who participated in the Prevention of Overweight in Infancy (POI) randomised control trial. B4SC anthropometric measures were compared to POI anthropometric values that had been interpolated to align with the date of the B4SC assessment. RESULTS:Interclass correlation coefficients between values from the two sources (0.93-0.98) suggested that across all these measures, most variation depended on between child effects rather than between source effects. A paired t-test found no evidence for differences between POI and B4SC height values. B4SC weights were a mean of 0.45kg heavier, and BMIs a mean of 0.41kg/m2 greater. Exploratory analyses demonstrated that greater overestimation of weight by the B4SC was associated with assessments on colder days. CONCLUSION:B4SC measurements of weight were greater than values obtained from interpolating the POI standardised research assessments. Interestingly, this overestimation was inversely associated with the average temperature on the day when the B4SC occurred. These findings suggest that universal health services that monitor growth in children could be improved by including standardised procedures to account for non-removal of clothing.