What is the prevalence of Cow's Milk Protein Allergy (CMPA) in infants?

Prevalence of Cow's Milk Protein Allergy (CMPA) in Infants

Cow's milk protein allergy (CMPA) affects approximately 2-3% of infants in the first year of life, making it the most common food allergy in early childhood. 1

Epidemiology of CMPA

CMPA prevalence varies based on diagnostic criteria and study methodology:

• The most reliable estimates indicate a 2-3% incidence in infants under one year 1
• Some studies report ranges between 2-7.5% in the first year of life 2
• Symptoms suggestive of CMPA may be encountered in approximately 5-15% of infants, emphasizing the importance of proper diagnostic confirmation 1
• In exclusively breastfed infants, reproducible clinical reactions to cow's milk protein in human milk occur in approximately 0.5% 1, 3

Clinical Presentation and Diagnosis

CMPA can manifest through various symptoms across multiple organ systems:

• Most infants develop symptoms before 1 month of age, often within 1 week after introduction of cow's milk protein-based formula 1
• Approximately 50-60% present with cutaneous symptoms (urticaria, angioedema, atopic dermatitis) 1, 4
• 50-60% experience gastrointestinal symptoms (vomiting, diarrhea, blood in stool) 1, 4
• 20-30% develop respiratory symptoms (wheezing, rhinitis, coughing) 1
• The majority of affected infants have two or more symptoms from two or more organ systems 1

CMPA is classified into two main types:

1. IgE-mediated reactions: Typically appear within minutes to 2 hours after ingestion 4
2. Non-IgE-mediated reactions: Usually manifest 2-72 hours after ingestion 4

Risk Factors and Associated Conditions

Several factors increase the risk of developing CMPA:

• Family history of atopy 4
• Presence of other allergic conditions 4
• Early introduction of cow's milk formula 4
• 47.5% of infants with CMPA may have atopic dermatitis 5
• 25.5% may experience wheezing 5
• Up to 27% develop allergies to foods other than milk 5

Natural History and Prognosis

The prognosis of CMPA is generally favorable:

• Remission rates are approximately 45-50% at 1 year of age 1, 3
• 60-75% at 2 years of age 1, 3
• 85-90% at 3 years of age 1, 3

However, children with CMPA have increased risk for:

• Associated adverse reactions to other foods (up to 50%) 1
• Development of allergies to inhalants (50-80% before puberty) 1
• An early increased IgE response to cow's milk protein is associated with persistent allergy 1

Clinical Implications

The accurate diagnosis of CMPA is crucial to avoid:

• Overdiagnosis leading to unnecessary dietary restrictions 4
• Underdiagnosis resulting in persistent symptoms and potential growth issues 4
• Growth concerns: infants with CMPA receiving appropriate substitute formula generally show normal weight and height at 2 years, although height percentiles tend to be better than weight percentiles 5

Diagnostic Pitfalls

Common challenges in CMPA diagnosis include:

• Distinguishing between CMPA and cow's milk protein intolerance (non-immunological reactions) 3
• Relying solely on clinical symptoms without confirmation through elimination and challenge procedures 1, 3
• No single laboratory test is diagnostic of CMPA 3

Understanding the true prevalence of CMPA helps clinicians maintain appropriate clinical suspicion while avoiding overdiagnosis, ensuring optimal management of affected infants.