Seasonal distribution in newly diagnosed cases of eosinophilic esophagitis in adults.

OBJECTIVES: The etiology of eosinophilic esophagitis (EoE) is not well understood. It has been proposed that eosinophils migrate to the esophagus in response to various ingested and inhaled allergens. Recent reports in children found an increased proportion of cases of EoE during months with higher outdoor aeroallergens. To our knowledge, this has not been evaluated in adults. We aimed to determine whether there is a seasonal distribution in the number of newly diagnosed cases of EoE in an adult population. METHODS: We conducted a retrospective review of consecutive adult cases newly diagnosed with EoE in 1 year. Cases were grouped based on the index month when the diagnosis was made at endoscopy. To test the consistency of the observations, a second cohort of consecutive cases of similar sample size diagnosed at a different period in time was also analyzed. RESULTS: In total, 41 patients were diagnosed with EoE at our center during the study period, providing an annual prevalence of 0.98%. More cases were diagnosed with EoE during the months of April and May than any other month (P<0.001). When patients were grouped seasonally, there was a significant increase of EoE cases in spring and summer months (n=28) when compared with the fall and winter months (n= 13) (P=0.019). Analysis of the second cohort of cases (n=37) from 2002 to 2006 confirmed a similar seasonal diagnostic pattern for EoE during the outdoor seasons. CONCLUSIONS: Our data demonstrate that EoE has a seasonal prevalence in adults. The seasonal variation pattern found in newly diagnosed EoE cases in adults supports the potential role of aeroallergens in the pathogenesis of EoE.