shapecoder: a new method for visual quantification of body mass index in young children

Summary Background Few tools exist to quantify body mass index visually. Objective To examine the inter‐rater reliability and validity (sensitivity and specificity for overweight/obesity and obesity) of a three‐dimensional visual rating system to quantify body mass index (BMI) in young children. Methods Children (n = 242, mean age 5.9 years, 50.0% male; 40.5% overweight/ obese) participated in a videotaped protocol and weight and height were measured. Research staff applied a novel three‐dimensional computer‐based figure rating system (shapecoder) to the child's videotaped image. Inter‐rater reliability was calculated, as well as correlation with measured body mass index (BMI) and sensitivity, specificity, positive predictive value and negative predictive value for overweight/obesity and obesity. Results Inter‐rater reliability was excellent (intraclass correlation coefficient = 0.98). The correlation of shapecoder‐generated BMI with measured BMI was 0.89. For overweight/obesity, the sensitivity, specificity, positive predictive value and negative predictive value were 62%, 97%, 94% and 79% respectively. For obesity, these values were 65%, 99%, 97% and 92% respectively. Conclusion shapecoder provides a method to quantify child BMI from video images with high inter‐rater reliability, fair sensitivity and good specificity for overweight/obesity and obesity. The approach offers an improvement over existing two‐dimensional rating scales for BMI.