Cow's milk allergy overdiagnosis: prevalence, characteristics and risk factors
File(s)
Author(s)
Allen, Hilary
Type
Thesis
Abstract
Background
Cow’s milk allergy (CMA) affects about 1% of European infants but overdiagnosis is common. Concern has been raised about promotion of CMA overdiagnosis by formula milk companies. However, the extent and nature of CMA overdiagnosis and its relationship with formula sponsorship have not been formally evaluated.
Aims
This thesis characterised CMA overdiagnosis by estimating prevalence, describing triggers and identifying risk factors. To explore the impact of formula sponsorship, independent clinical practice guidance for CMA was developed through Delphi consensus, and compared with diagnosis and management recommendations from formula-funded guidelines.
Methods
Three independent studies were performed. First, analysis of national prescribing databases to document low-allergy formula prescribing. Second, analysis of primary care records for a cohort of English children characterised for CMA. Third, a Delphi consensus study to develop independent CMA clinical practice guidance.
Results
Low-allergy formula prescriptions in England, Norway and Australia increased 2-3-fold over 11 years, with prescribed volumes ~10-fold greater than expected.
In a clinical trial cohort, parent-reported CMA overdiagnosis affected 16.1% infants compared with 1.4% true confirmed CMA. CMA overdiagnosis occurred at median 49 days old, mainly for gastrointestinal symptoms. Half of those over diagnosed were prescribed low-allergy formula. In this cohort, high primary care practice prescribing of low-allergy formula in the year prior to birth was associated with increased CMA overdiagnosis. Exclusively formula-fed infants had increased low-allergy formula prescription.
Non-conflicted guidance for CMA diagnosis and management was more supportive of breastfeeding women, included narrower criteria for CMA and more limited recommendations for specialised formula, compared with formula-funded guidance.
Conclusions
CMA overdiagnosis is common and ~90% of infants with a CMA diagnosis probably don’t have CMA. Primary care practice prescribing habits are a risk factor for CMA overdiagnosis. Independent CMA guidance may protect mothers and infants from CMA overdiagnosis better than formula industry-funded guidance.
Cow’s milk allergy (CMA) affects about 1% of European infants but overdiagnosis is common. Concern has been raised about promotion of CMA overdiagnosis by formula milk companies. However, the extent and nature of CMA overdiagnosis and its relationship with formula sponsorship have not been formally evaluated.
Aims
This thesis characterised CMA overdiagnosis by estimating prevalence, describing triggers and identifying risk factors. To explore the impact of formula sponsorship, independent clinical practice guidance for CMA was developed through Delphi consensus, and compared with diagnosis and management recommendations from formula-funded guidelines.
Methods
Three independent studies were performed. First, analysis of national prescribing databases to document low-allergy formula prescribing. Second, analysis of primary care records for a cohort of English children characterised for CMA. Third, a Delphi consensus study to develop independent CMA clinical practice guidance.
Results
Low-allergy formula prescriptions in England, Norway and Australia increased 2-3-fold over 11 years, with prescribed volumes ~10-fold greater than expected.
In a clinical trial cohort, parent-reported CMA overdiagnosis affected 16.1% infants compared with 1.4% true confirmed CMA. CMA overdiagnosis occurred at median 49 days old, mainly for gastrointestinal symptoms. Half of those over diagnosed were prescribed low-allergy formula. In this cohort, high primary care practice prescribing of low-allergy formula in the year prior to birth was associated with increased CMA overdiagnosis. Exclusively formula-fed infants had increased low-allergy formula prescription.
Non-conflicted guidance for CMA diagnosis and management was more supportive of breastfeeding women, included narrower criteria for CMA and more limited recommendations for specialised formula, compared with formula-funded guidance.
Conclusions
CMA overdiagnosis is common and ~90% of infants with a CMA diagnosis probably don’t have CMA. Primary care practice prescribing habits are a risk factor for CMA overdiagnosis. Independent CMA guidance may protect mothers and infants from CMA overdiagnosis better than formula industry-funded guidance.
Version
Open Access
Date Issued
2024-11-30
Date Awarded
01/10/2025
License URL
Advisor
Boyle, Robert
Santer, Miriam
Murphy, Andrew
Sponsor
Irish College of General Practitioners
Publisher Department
National Heart & Lung Institute
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)