An Improved Pediatric Weight Estimation Strategy

There exist a number of pediatric health care settings wherein time and/or resource constraints do not permit care providers to reliably assess children’s weight. This study describes the development and validation of a pediatric weight estimation strategy that addresses the limitations of currently available weight estimation methods. Demographic and anthropometric data on children 2 months to 16 years of age were extracted from the National Health and Nutrition Examination Survey. Datasets were randomly assigned into a method development set (n=17,328) and a method validation set (n=1,938). Humeral length and mid-upper arm circumference were used to develop a weight estimation method. The predictive performance of this method was evaluated and compared with the performance of 13 previously published weight estimation methods. We also developed a measurement device that performs both measurements simultaneously requiring simple addition and no external references to arrive at the weight estimate. The method developed in this study (Mercy method) outperformed the 13 other published methods when evaluated by goodness-of-fit (r 2 =0.98 vs. 0.69 to 0.87; slope=0.97 vs. 0.43 to 0.96; intercept 0.9 vs. 3.1 to 11.8), mean error (-0.40 kg vs.-10.88 to 2.23), mean percentage error (-0.46% vs. -16.84 to 3.51), root mean square error (3.65 kg vs. 3.42 to 16.96) and percentage of children in agreement within 10% of actual weight (79% vs. 17.8 to 45.3). The Mercy method represents a significant improvement over existing age-based, length-based and habitus-based weight estimation strategies.