Prognosis of infantile food protein-induced enterocolitis syndrome in Japan.

Background: Although serum C-reactive protein (CRP) and the percentage of eosinophils in peripheral blood (Eo) are increased at onset in infants with food protein-induced enterocolitis syndrome (FPIES), the relationship of these laboratory findings to prognosis is presently unknown.

Methods: Correlation of serum CRP and Eo at onset with prognosis was analyzed in 32 patients with FPIES caused by cow's milk (CM).

Results: The rate of tolerance acquisition was 18.8%, 56.3%, 87.5%, and 96.9% at the ages of 6, 12, 24, and 36 months, respectively. Serum CRP increased in 50% of subjects at onset (median, 0.21 mg/dL; range, <0.20-18.2 mg/dL) and Eo was elevated in 71.9% of subjects at onset (median, 7.1%; range, 1.0-50.5%). Age at tolerance acquisition was significantly positively correlated with serum CRP at onset (r = 0.45, P < 0.01), and significantly negatively correlated with Eo at onset (r = -0.36, P < 0.05). Although CM-specific immunoglobulin E antibody (sIgE) was positive in nine of 32 FPIES patients at onset (median, 0.93; range, 0.38-18.9 kU/L), it decreased thereafter. CM-sIgE at onset did not correlate significantly with prognosis (r = 0.22, P > 0.05).

Conclusions: Serum CRP is not only an indicator of the activity of intestinal inflammation, it is also a useful parameter of poor prognosis in FPIES. In contrast, eosinophilia at onset could be used as a marker of good prognosis, suggesting that it has some beneficial effects in the pathophysiology of FPIES.