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‘Well-meaning’ guidelines may be promoting over-diagnosis of cow’s milk allergy in babies, research suggests

Guidelines produced to help doctors diagnose cow’s milk allergy may “unintentionally medicalise normal infant symptoms”, a new study has indicated.

While the condition in known to only affect one in 100, prescription rates for specialist formula has increased.

The research team, led by the University of Bristol, found that while 75 per cent of babies have two or more symptoms in their first year – bringing up milk, vomiting, colic, loose stools or constipation – the rates of young children with the condition are much lower.

They say that these symptoms are common, making cow’s milk allergy difficult to diagnose.

Senior co-researcher and children’s allergy doctor, Dr Michael Perkin, from the Population Health Research Institute at St George’s, University of London, said: “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.

“Parents of young infants are often seen in clinics, worried about a medical cause for their infant’s symptoms such as colic, bringing up milk or loose stools. However, our research confirms that these symptoms are extremely common. In an otherwise healthy infant, an underlying cause is unlikely. Incorrectly attributing these symptoms to cow’s milk allergy is not only unhelpful, but it may also cause harm by discouraging breastfeeding.”

As part of their study, researchers found that rates of symptoms were highest at three months, when the infants were being exclusively breastfed. By six months, there was no difference in the number of babies with symptoms between those drinking cow’s milk and those who were not. This has led the research team to suggest that most of the symptoms listed in the guidelines used to diagnose cow’s milk allergy are common and normal.

Lead researcher Dr Rosie Vincent, Honorary Clinical Research Fellow at the Centre for Academic Primary Care, University of Bristol, said: “Guidelines, designed to help the non-specialist to diagnose cow’s milk allergy in infants may unintentionally medicalise normal infant symptoms and promote over-diagnosis of cow’s milk allergy.”

Professor Matthew Ridd, a GP and senior co-researcher at the Centre for Academic Primary Care, University of Bristol, added: “Our study was based on the international Milk Allergy in Primary Care guideline but our results are likely to apply to other cow’s milk allergy guidelines. Well-meaning guidelines need to be supported by robust data to avoid the harms from over-diagnosis, which may be greater than the damage of delayed diagnoses that they seek to prevent.”

The study has been published in the journal, Clinical and Experimental Allergy.

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