For the article on Medscape: Click: here
Most non-scale methods estimate the child's weight based upon only age, length, height, or the circumference of the mid-upper arm or other anatomic site.
To address what it saw as the limitations of single-variable weight estimation methods, one group of researchers in the United States and United Kingdom has developed a new method that includes both humeral length and mid-upper arm circumference (MUAC). They reported their findings online February 26 in Archives of Disease in Childhood.
The Mercy TAPE ("TAking the guesswork out of Pediatric weight Estimation") method performed comparably among children of varying races and ethnicities, and was more accurate than either the humeral length or the MUAC alone, the authors wrote.
"The Mercy TAPE, developed at Children's Mercy Hospital, is a very easy paper-based device that requires no mathematical calculations and can be used by people with no sophistication. All they have to do is follow an instruction, and they can read or be shown how to do it. So it is very adaptable," said senior author Dr. Gregory L. Kearns of Children's Mercy Hospital and the University of Missouri-Kansas City School of Medicine, in Kansas City, Missouri, in a phone call with Reuters Health.
"In terms of prediction accuracy, the Mercy TAPE has so far outperformed many of the existing weight prediction methods," Dr. Kearns said.
"The Mercy TAPE is good for any child anywhere, at any time, irrespective of their habitus. It's easy, quick, simple and has no real constraints in its application," he said.
Whether the person weighing the child according to the Mercy TAPE method uses a standard tape measure or the actual Mercy TAPE paper tool, measurements are taken of the humeral length and mid-upper arm circumference (MUAC) on the same limb.
Each value is assigned a fractional weight that can be looked up on a reference table if using a standard tape measure or read directly from the Mercy TAPE tool. The two numbers are added to estimate the child's weight. The method has no height restrictions and is applicable over a very broad range of ages, the authors wrote.
As reported in a separate paper online February 19 in Emergency Medicine, in the CORKSCREW study from Ireland, Dr. Darko Skrobo of Cork University Hospital and colleagues found that by switching from the widely used Advanced Pediatric Life Support (APLS) formula to the Luscombe and Owens (LO) formula, they could more accurately estimate the weights of Irish children in life-threatening situations.
The APLS formula, i.e., age plus four, multiplied by two, is widely used in Irish hospitals, the authors wrote. But it was created in the 1950s, Dr. Skrobo said, and based its data on post-war children in the UK.
As the prevalence of obesity increases, the formula's accuracy has been questioned. The newer LO formula, i.e., age multiplied by three, plus seven, has been suggested to replace it.
The LO formula can be used over a larger age range than other formulas and it eliminates the need to memorize several different formula components, the authors say.
To gather data on the weights and ages of the Cork pediatric population between ages one and 15 years, and to identify which of the two formulas is most accurate, the researchers collected data from patient charts in their Emergency Department.
From the 3,155 children in their study (1,344 girls and 1,811 boys), the researchers found that, overall, the APLS formula underestimated the children's weights by a mean of 20.3%.
By contrast, the LO formula underestimated the children's weights by a mean of 4.0%.
"The LO formula has been shown to overestimate weights in certain age ranges. In our study, it was between four and nine years of age, with a maximum 7.2% overestimation at age six years," Dr. Skrobo said in an email. "In clinical practice, a 7.2% overestimation in a six-year-old equals 1.72 kg. Each department must decide if this deviation is an acceptable compromise in order to gain better estimation in all other ages. I personally believe it is!"
"Age-based weight estimation formulas remain the only methods that have been validated in emergency situations, and that can help calculations of fluids, glucose, drug concentrations, etc., before the crucially ill child arrives," he said.
"It surprises me that many emergency departments still have not conducted their own research into this matter. Under-resuscitation of children affects outcomes. Each emergency department strongly needs to perform audits and review its own methods, to investigate what method is most accurate for their local population," he said.
"Weight estimation methods are highly population- and geography-specific, and the LO formula has been validated in several studies and proven to be a superior age-based weight estimation formula in many western emergency departments," he said.
"In emergency situations and where fully calibrated weighing scales are not functioning, weight estimation saves lives," he said.
Drs. Kearns and Skrobo were not involved in each other's studies.
Arch Dis Child 2014.
Emerg Med J 2014.