UCLA

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) serves 50% of infants and 25% of preschool-aged children in the U.S. and collects height and weight measurements from eligible children every six months, making WIC data a valuable resource for studying childhood growth and obesity.  We assessed the accuracy of measurements collected by WIC staff by comparing them to “gold standard” measurements collected by trained research staff.  At seven WIC clinics in southern California, 287 children ages 2-5 years measured by WIC staff using WIC standard protocol were re-measured by research staff using a research protocol (duplicate measurements with shoes and outerwear removed taken by trained personnel).  Intraclass correlation coefficients measuring agreement between WIC and research protocol measurements for height, weight and body mass index (BMI) were 0.96, 0.99 and 0.93, respectively.  Although WIC measurements overestimated height by 0.6 cm and weight by 0.05 kg on average, BMI was underestimated by only 0.15 kg/m² on average.  WIC BMI percentiles classified children as overweight/obese versus underweight/normal with 86% sensitivity and 92% specificity.  We conclude that height, weight and BMI measurements of children aged 2-5 years collected by trained WIC staff are sufficiently accurate for monitoring and research purposes.