Clinical characteristics, prognosis, and risk factors for tolerance development in food protein-induced allergic proctocolitis: a retrospective cohort study.

Background: Food protein-induced allergic proctocolitis (FPIAP) is a non-IgE-mediated food allergy that primarily affects infants. Although the prognosis is generally favorable, a subset of patients remains intolerant to food proteins beyond the first year of life. The roles of early nutrition and genetic factors in the development of oral tolerance remain unclear. This study aimed to identify clinical predictors of the prognosis of FPIAP and inform evidence-based elimination dietary management. Methods: This retrospective cohort study included pediatric patients diagnosed with FPIAP at the Beijing Children's Hospital, Capital Medical University, between January and July 2024. Clinical data were collected from medical records. A follow-up survey was conducted in June 2025 to assess food reintroduction success and the development of atopic comorbidities. Logistic regression models were used to identify the factors influencing the development of oral tolerance. Results: A total of 163 children (84 males, 79 females) were included, with a median age at symptom onset of 2 months. Beyond hematochezia, the predominant clinical manifestations included diarrhea, mucoid stools, and cutaneous symptoms (eczema or urticaria). Cow milk protein was the primary trigger in 98.8% of cases. A total of 108 infants (66.3%) achieved oral tolerance by 12 months. Platelet counts (PLT) and platelet crit (PCT) values were significantly higher in children who acquired oral tolerance after 12 months of age compared to those who acquired oral tolerance by 12 months of age (both P<0.05). The rates of family history of allergy (43.5% Conclusions: FPIAP generally carries a favorable prognosis, with 66.3% of affected infants achieving oral tolerance within the first year of life. A family history of allergic diseases and multiple food allergies were associated with delayed oral tolerance. Although exclusive breastfeeding was more frequently observed among infants who developed early tolerance, this association is likely influenced by underlying differences in disease severity and should not be interpreted as evidence of a causal protective effect. These findings underscore the clinical value of early breastfeeding guidance and individualized elimination diet strategies in optimizing outcomes for infants with FPIAP.