Babies may be overdiagnosed with cow's milk allergy: U.K. study

An infant being fed formula from a bottle. (AP / James B. Hale)

A recent analysis out of the United Kingdom has found that international guidelines used to help diagnose cow's milk allergy may result in infants being overdiagnosed — which in turn could discourage breastfeeding.

Published in the journal Clinical and Experimental Allergy on Wednesday, the research led by the University of Bristol in England found that the majority of symptoms listed under cow's milk allergy guidelines are not only common and normal, but also not caused by cow's milk allergy itself.

"Guidelines, designed to help the non-specialist to diagnose cow's milk allergy in infants may unintentionally medicalize normal infant symptoms and promote overdiagnosis of cow's milk allergy," Dr. Rosie Vincent, honorary clinical research fellow at the Centre for Academic Primary Care at the University of Bristol who led the research, said in a news release.

The researchers used data from the Enquiring About Tolerance study in the U.K. involving 1,303 infants between three and 12 months old, which counted how many infants had cow's milk allergy symptoms on a monthly basis, as defined in the international Milk Allergy in Primary Care (iMAP) guideline.

Cow's milk allergy, the researchers say, can result in acute or delayed symptoms, the latter of which is more varied.

Delayed symptoms include gut and skin symptoms such as posseting, or bringing up milk, and vomiting, colic or prolonged and intense crying in an otherwise healthy infant, loose stools or constipation, and eczema.

Since many of these symptoms are already common in infants, the researchers say this makes delayed cow's milk allergy difficult to diagnose.

However, they say one in four parents reported two or more possible mild to moderate symptoms each month, with symptoms most common at three months old when all children were fully breastfed and not directly consuming cow's milk.

At six months old, the analysis found no difference in the number of children with two or more symptoms, whether they had consumed cow's milk or not.

"Our findings come against a background of rising prescription rates for specialist formula for children with cow's milk allergy, which is completely out of proportion to how common we know the condition is," said Dr. Michael Perkin, senior co-researcher and children's allergy doctor from the Population Health Research Institute at St George's, University of London.

Perkins adds that "incorrectly attributing these symptoms to cow's milk allergy is not only unhelpful, but it may also cause harm by discouraging breastfeeding."

Dr. Matthew Ridd, a general practitioner and senior co-researcher at the University of Bristol's Centre for Academic Primary Care, said while the study was based on iMAP, the results will likely apply to other cow's milk allergy guidelines, as well.

"Well-meaning guidelines need to be supported by robust data to avoid the harms from overdiagnosis, which may be greater than the damage of delayed diagnoses that they seek to prevent," Ridd said.