Identification, epidemiology, and chronicity of pediatric esophageal eosinophilia, 1982-1999

Background: Eosinophilic esophagitis (EE) is now a commonly encountered disorder that was rarely diagnosed a decade ago. Objective: We aimed to determine the epidemiologic and histologic features of retrospective pediatric esophageal eosinophilia before the first case of EE at our institution was recognized. Methods: Esophageal biopsy specimens obtained between 1982 and 1999 with reflux esophagitis were re-examined and reorganized into 2 groups based on peak esophageal eosinophil number (<15 eosinophils per high-powered field [hpf] and >= 15 eosinophils/hpf). The epidemiology and histology of the entire cohort and a population-based cohort were evaluated. Results: Eight hundred seven biopsy specimens from 666 patients were re-examined; 198 patients had 15 eosinophils/hpf or greater. Among a population-based cohort of patients with 15 eosinophils/hpf or greater, there was a modest increase in incidence (P < .001; incidence rate ratio, 1.18; 95% CI, 1.09-1.28). After correcting for a 40-fold increase in the number of endoscopies during this time period, the proportion of biopsy specimens with 15 eosinophils/hpf or greater did not change (0.08 in 1982 vs 0.08 in 1996 [peak]; P = .9; incidence rate ratio, 1.02; 95% CI, 0.73-1.44). Patients who had as few as 5 eosinophils/hpf were more likely to have persistent esophageal eosinophilia on repeat esophagogastroduodenoscopy, evidence of basal layer hyperplasia, and lamina propria fibrosis compared with patients with less than 5 eosinophils/hpf (P < .001). Conclusions: Esophageal eosinophilia at levels consistent with EE was present among 30% of patients given diagnoses of reflux esophagitis, and the incidence of esophageal eosinophilia did not change over time. Patients with 5 eosinophils/hpf or greater had evidence of other histologic abnormalities and were likely to have persistent esophageal eosinophilia. (J Allergy Clin Immunol 2010;126:112-9.)