New international guidelines developed to help diagnose cow’s milk allergy may lead to over-diagnosis, according to University of Bristol-led research published in the journal Clinical and Experimental Allergy.
When an infant has a milk allergy, their immune system fights infections and overacts to the proteins found in cow’s milk. When the child has milk, the body thinks the proteins are harmful and fights against them. Causing an allergic reaction in which the body releases chemicals like histamine.
The new study found that three-quarters of infants have two or more symptoms at some point in the first year of life. The guidelines state this could be caused by a cow’s milk allergy, yet the condition only affects one in 100.
Cow’s milk allergy symptoms
Acute or delayed symptoms occur during an allergic reaction to cow’s milk. Delayed symptoms are varied, including both gut and skin side effects, such as bringing up milk and vomiting, colic, loose stools, or constipation, and flaring of eczema. However, many of these symptoms are common in infants, making diagnosing a cow’s milk allergy difficult.
Dr Rosie Vincent, Honorary Clinical Research Fellow at the Centre for Academic Primary Care, University of Bristol, who led the research, 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.”
The researchers from the University of Bristol, St Georges, University of London, Imperial College London, Kings College London, and St John’s Institute of Dermatology used data from the Enquiring About Tolerance report. It involved 1,303 infants aged between twelve months and three years with their parents tasked to record any symptoms their child experienced monthly. They counted how many infants had cow’s milk allergy symptoms each month, as defined in the International Milk Allergy in Primary Care (IMAP) guideline.
What did the researchers find?
Researchers found that one in four parents reported two or more possible “milk to moderate” symptoms every month. Symptoms were most prominent at three months old when all children were fully breastfed and not directly consuming cow’s milk. However, there were no differences in the number of children with two or more symptoms between those consuming and not consuming cow’s milk at six months old. These findings suggest that the majority of symptoms listed in cow’s milk allergy guidelines were common, normal and not caused by cow’s milk allergy.
Senior co-researcher and children’s allergy doctor, Dr Michael Perkin, from the Population Health Research Institute at St George’s, University of London, added: “Our findings come against a background of rising prescription rates for a 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.”
Professor Matthew Ridd, a GP and senior co-researcher at the Centre for Academic Primary Care, University of Bristol, said: “Our study was based on IMAP, 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.”
