Predictors for late tolerance development in food protein-induced allergic proctocolitis

Background: Food protein-induced allergic proctocolitis (FPIAP) is a non-immunoglobulin E (IgE) mediated food allergy that typically presents with blood-mixed mucoid stool. Objective: To identify the predictors that affect the tolerance development in infants with FPAIP and laboratory as well as clinical differences between patients with early and with late tolerance. Methods: A total of 185 infants with FPIAP were included. The patients were grouped and analyzed based on laboratory tests and clinical characteristics. Results: The median (interquartile range [IQR]) age of onset of symptoms was 2.0 months (1.0-3.0 months). Symptoms began in severe cases in patients (n = 23) at a younger median (IQR) age (1.5 months [0.7-2.0 months]) than the group with nonsevere presentation (median 2.0 months [IQR 1.5-3.0 months]) (p < 0.001). The frequency of neutropenia (<1500/mm³) (p = 0.045) and eosinophilia (450 mm³) (p = 0.018) was increased in severe cases. Concomitant IgE-related food allergy (odds ratio [OR] 3.595 [95% confidence interval {CI}, 1.096-11.788], p = 0.035), non-IgE-mediated multiple food allergy (OR 3.577 [95% CI, 1.595-8.018], p = 0.002), feeding with cow's milk-based formula (at least once during infancy) (OR 2.517 [95% CI, 1.188-5.333], p = 0.016), and late complementary feeding (OR 5.438 [95% CI, 2.693-10.981], p < 0.001) were the predictors for late tolerance development. The estimated optimal cutoff value for introduction of complementary foods for the resolution of allergy was 5.5 months, with 69.4% sensitivity, 74.4% specificity, and an area under the curve of 0.737 (95% CI, 0.626-0.812) (p < 0.001). Conclusion: This study showed that the early introduction of complementary feeding accelerates tolerance development in FPAIP. A longer duration of an elimination diet has no impact on the resolution of allergy. Physicians should consider conservative avoidance measures and earlier introduction of complementary feeding in FPIAP.