Estimating Pediatric Weight: Mercy vs. Broselow Methods

Katherine Bakes, MD

The 2D- and 3D-Mercy TAPEs were more accurate than the Broselow tape.

Investigators who developed the Mercy method of estimating pediatric weight prospectively compared the performance of the 2D- and 3D-Mercy TAPE with the Broselow tape method in 624 children aged 2 months to 16 years (median age, 8.5 years; 77% white). The 2D-Mercy TAPE is a two-sided tape that measures humeral length on one side and mid-upper arm circumference on the other; the 3D- device is a single-sided tape that is folded to measure the mid-upper arm circumference and half-humeral length from a single position. Each length measurement corresponds to a weight value, with total estimated weight calculated by the sum of these fractional values.

Based on body mass indexes, 4% of children were underweight, 57% were normal weight, 14% were overweight, and 13% were obese; the remaining 12% were infants. Because the Broselow tape is only applicable for children <145 cm in height, only 415 children could be measured using this method. Percents of estimated weights that fell within 10% and 20% of actual weights were greater for the 2D-TAPE (76% and 98%, respectively) and 3D-TAPE (65% and 93%) than with the Broselow method (59% and 91%). Mean error was 0.3 kg for the 2D-TAPE, 0.2 kg for the 3D-TAPE, –1.3 kg for the Broselow method.

Citation(s):

Abdel-Rahman SM et al. Evaluation of the Mercy TAPE: Performance against the standard for pediatric weight estimation. Ann Emerg Med 2013 Apr 17; [e-pub ahead of print].