Taking the Guesswork out of Pediatric Weight Estimation

Studying a method of weight estimation for children using arm measurement, for when scales are unavailable or impractical.

This study is evaluating the predictive performance and equivalence of the Mercy Method™ weight estimation method in 625 children aged 2 months to 16 years at three U.S. sites. Study participants needed to be able to have arm measurements performed with a tape measuring device. The study period lasted approximately 20 minutes, and no follow-up visits occurred.


Many times, the weight of a child must be known, but a suitable scale is not available. Undeveloped countries often lack such devices, but sometimes, in developed countries, scales are unavailable (in cases of emergency or trauma) or impractical (in instances where casts, tubing, hoses, or other medical equipment pose difficulties). Therefore, methods for obtaining accurate weight are needed all around the world.

A few methods for estimating weight have been evaluated in pediatrics, such as relying on the child’s age, length, or a combination thereof. However, many of these strategies do not perform well in all children.

Investigators at Children’s Mercy Hospitals and Clinics in Kansas City, Missouri, have developed and validated a weight estimation method called the Mercy Method,™ which uses measurements of arm length and upper arm circumference obtained with a tape measuring device to predict weight. This method has outperformed other methods for predicting weight in children.

The Mercy Method™ tape study was conducted at three sites in the United States, with 625 children aged 2 months to 16 years who were able to have the measurements performed. The children’s involvement was completed within 20 minutes, and no follow-up visits were needed.


  • Evaluation of the Mercy TAPE: performance against the standard for pediatric weight estimation. Annals of Emergency Medicine • October 2013. Abdel-Rahman SM, Paul IM, James LP, Lewandowski A; Best Pharmaceuticals for Children Act-Pediatric Trials Network. We assessed the performance of 2 new devices (2D- and 3D-Mercy TAPE) to implement the Mercy Method for pediatric weight estimation and contrasted their accuracy with the Broselow method. We enrolled children aged 2 months through ...


Pediatric Academic Societies Annual Meeting, May 4-7, 2013

The Mercy TAPE: A New Device for Pediatric Weight Estimation
Paul I, James L, Lewandowski A, Abdel-Rahman S


Published; clinical study report submitted to FDA

ClinicalTrials.gov identifier:

Principal Investigator:
Susan M. Abdel-Rahmen, PharmD
Children’s Mercy Hospital
Kansas City, MO


  • Mercy TAPE moves closer to market The FDA has approved the 510(k) application for the Mercy TAPE—an anthropometric-based device developed by Dr. Susan Abdel-Rahman at Children’s Mercy Hospital in Kansas City that predicts weight in children 2 months through 16 years of age. The results from the PTN study validating this device appeared in the Annals of Emergency Medicine in 2013. Section ...
  • The PTN Mercy Method tape study locks its database The PTN’s Mercy Method™ tape study has locked its database containing information from 625 patients. Database lock means that all clinical trial data have been reviewed, queries have been resolved and issues addressed, and the database cannot be altered in any way. The trial concluded enrollment in April of this year. The Mercy Method™—developed at Children’s ...
  • The PTN Mercy Method tape study completes enrollment The PTN’s Mercy Method™ tape study has successfully completed enrollment of 625 evaluable patients. Trial enrollment was concluded in less than two months. The study team attributes this impressive enrollment rate to the efforts of lead investigator Susan Abdel-Rahman, PharmD, of Children’s Mercy Hospitals and Clinics in Kansas City, Missouri; principal investigators Ian Paul, MD, of ...