Histologic improvement after 6 weeks of dietary elimination for eosinophilic esophagitis may be insufficient to determine efficacy

Background: Elimination diets are used to treat eosinophilic esophagitis (EoE), with success (remission) defined at endoscopy and oesophageal biopsy as fewer than 15 eosinophils per high power field (HPF). Response is assessed after 6 weeks of treatment by convention, but we have observed that this period of time may be insufficient. objective: To characterise a subset of patients with EoE who require prolonged (>6 weeks) of dietary therapy to achieve histologic remission. Methods: A retrospective search of electronic medical records of 2 cohorts with EoE attending the Department of Gastroenterology, University of Chapel Hill North Carolina, and Eastern Health, Melbourne Australia. Patients who underwent elimination diet, had esophageal biopsy after 6 or more weeks of dietary restriction that demonstrated ongoing esophageal inflammation (>15 eosinophils per HPF), and who then continued dietary therapy followed by repeat endoscopy demonstrating remission (<15 eosinophils per HPF) were included. Results: Seven patients met inclusion criteria, average esophageal eosinophil counts prior to diet was 38.5 (range, 15-65). Following the initial period of diet (mean of 6 weeks and 4 days) eosinophil count decreased (average, 21.5/HPF; range 15-40/HPF). After extended dietary elimination (mean, 13 weeks; range, 7-22 weeks), histological resolution was achieved (average peak eosinophil count of 5.2; range, 0-44) in all cases. Endoscopic appearance and symptoms both improved following the initial period of dietary elimination, thereby preceding the histological resolution, and were sustained. Conclusion: A subset of patients has full histologic response to prolonged elimination diet, that lags initial symptomatic and endoscopic improvement.