Food Protein-Induced Allergic Proctocolitis: Over- or Underdiagnosed?

BACKGROUND: Food protein-induced allergic proctocolitis (FPIAP) is an early and common manifestation of food allergy, yet its epidemiology and relationship to other allergic diseases remain unclear. OBJECTIVE: To prospectively define the incidence of FPIAP as it is being diagnosed clinically in the community and to identify factors associated with its development. METHODS: 1003 of 1162 eligible serial healthy newborn infants recruited from a single suburban pediatrics practice were followed prospectively for the diagnosis of FPIAP. Investigators reviewed each case to confirm pre-specified inclusion criteria, including documented gross or occult blood in the stool. RESULTS: 903 infants were analyzed (46% female, 89% term, 32% caesarian-section, 9% neonatal antibiotics). 153 cases met inclusion criteria, a cumulative incidence of 17%, while 63 (7%) had gross blood. Infants initially fed both breastmilk and formula were 61% less likely to develop FPIAP compared to those exclusively formula-fed (HR 0.39, P = .005). Breastmilk and formula at any point during the first 4 months was also associated with lower risk compared to exclusive formula or exclusive breastmilk (HR 0.44, P = .005; HR 0.62, P = .0497). Eczema (OR 1.5 [1.1, 2.2], P = .02) or a first degree relative with food allergies (OR 1.9 [1.2, 2.8], P = .005) were among risk factors for FPIAP development. CONCLUSION: The prospectively defined incidence of FPIAP when diagnosed clinically by community pediatricians without challenge is markedly higher than published estimates. Combination feeding of formula and breastmilk is associated with the lowest rate of FPIAP in this population.