Comparison of two waist circumference measurement protocols: the SEARCH for diabetes in youth study

Background Reports comparing waist circumference (WC) measurements from young populations are scarce. Objectives We compared two protocols for measuring waist circumference in a sample of youth with diabetes. Methods Participants were enrolled in the SEARCH for Diabetes in Youth Study (SEARCH). WC was measured at least twice by the National Health and Nutrition Examination Survey (NHANES) protocol and twice by the World Health Organization (WHO) protocol. Method‐specific averages were used in these analyses. Results Among 6248 participants, the mean NHANES WC (76.3 cm) was greater than the mean WHO WC (71.9 cm). Discrepancies between protocols were greater for females than males, among older participants, and in those with higher body mass index (BMI). In both sexes and four age strata, the WCs using either method were highly correlated with BMI z‐score. The within‐method differences between the first and second measurements were similar for the two methods. Conclusions These analyses do not provide evidence that one of these two methods is more reproducible or is a better indicator of obesity as defined by BMI z‐scores.