International guidelines designed to help healthcare professionals diagnose cow’s milk allergy (CMA) in infants may be leading to overdiagnosis, a report in
The BMJ has warned.
A team from the University of Bristol, St George’s University of London, and King’s College, London assessed 1,300 infants and found that nearly three quarters aged 3–12 months had mild to moderate symptoms of CMA as described in the international Milk Allergy in Primary Care (iMAP) guideline.
The study was carried out following an investigation by The BMJ which found that prescriptions of specialist formula milk for infants with CMA increased by nearly 500% from 2006 to 2016, and NHS spending on these products increased by nearly 700% over the same period.
This was despite the absence of evidence that such a large increase in true prevalence had occurred. Prevalence of CMA is estimated to be 2%, with only 1% experiencing immunoglobulin E-mediated allergy, which causes immediate and consistent symptoms and can be diagnosed through testing. Non-IgE-mediated CMA has delayed symptoms, and is diagnosed by observing clinical improvement when cow’s milk protein is avoided.
In this study, parents were asked to record any symptoms their child had each month, including colic, posseting, loose stools or constipation, and eczema flare-ups. One in four parents reported two or more possible mild to moderate symptoms every month. Symptoms occurred most often in infants aged 3 months, when none were consuming cow’s milk. Only 4.3% experienced severe symptoms. At age 3-6 months, half the children were introduced to six allergenic foods, including cow’s milk, alongside breastfeeding. The other group was exclusively breastfed. By 6 months, there was no significant difference in the incidence of symptoms between the two groups.
The authors said: ‘Parents are often seen in clinics, worried about a medical cause for their infant’s symptoms. However, our research confirms that these symptoms are extremely common but in an otherwise healthy infant, an underlying cause is unlikely. Incorrectly attributing these symptoms to cow’s milk allergy is not only unhelpful but may also cause harm by discouraging breastfeeding.’
Although independently produced, the iMAP guideline is frequently used by the formula industry in marketing and educational materials.
Mahase E. BMJ 2021;375:n3037. Published 8 December 2021.