title: Seasonal variation in detection of oesophageal eosinophilia and eosinophilic oesophagitis.
abstract: BACKGROUND
  Seasonal variation has been reported in diagnosis of eosinophilic oesophagitis (EoE), but results are not consistent across studies and there are no national-level data in the USA.
  
  
  OBJECTIVE
  To determine if there is seasonal variation in diagnosis of oesophageal eosinophilia and EoE in the USA, while accounting for factors such as climate zone and geographic variation.
  
  
  METHODS
  This was a cross-sectional study using a USA national pathology database. Patients with oesophageal eosinophilia (≥15 eosinophils per high-power field) comprised the primary case definition and were compared to those with normal oesophageal biopsies. We calculated the crude and adjusted odds of oesophageal eosinophilia by season, as well as by day of the year. Sensitivity analyses were performed using more restrictive case definitions of EoE, and after stratification by climate zone.
  
  
  RESULTS
  Exactly, 14 524 cases with oesophageal eosinophilia and 90 459 normal controls were analysed. The adjusted odds of oesophageal eosinophilia were higher in the late spring and summer months, with the highest odds in July (aOR: 1.13; 95% CI: 1.03-1.24). These findings persisted with increasing levels of oesophageal eosinophilia, as well as across EoE case definitions. Seasonal variation was strongest in temperate and cold climates, and peak diagnosis varied by climate zone.
  
  
  CONCLUSIONS
  There is a mild but consistent seasonal variation in the diagnosis of oesophageal eosinophilia and EoE, with cases more frequently diagnosed during summer months. These findings take into account climate and geographic differences, suggesting that aeroallergens may contribute to disease development or flare.
authors.affiliation: Center for Esophageal Diseases and Swallowing, Division of Gastroenterology and Hepatology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, NC, USA.|Center for Gastrointestinal Biology and Disease, Division of Gastroenterology and Hepatology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
authors.forename: E T
authors.initials: ET
authors.lastname: Jensen
authors.affiliation: Center for Esophageal Diseases and Swallowing, Division of Gastroenterology and Hepatology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
authors.forename: N D
authors.initials: ND
authors.lastname: Shah
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA.|Nicholas School of the Environment, Duke University, Durham, NC, USA.
authors.forename: K
authors.initials: K
authors.lastname: Hoffman
authors.affiliation: Portland VA Medical Center and Oregon Health & Science University, Portland, OR, USA.
authors.forename: A
authors.initials: A
authors.lastname: Sonnenberg
authors.affiliation: Miraca Life Sciences Research Institute, Irving, TX, USA.|Dallas Veterans Affairs Medical Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Genta
authors.affiliation: Center for Esophageal Diseases and Swallowing, Division of Gastroenterology and Hepatology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, NC, USA.|Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: E S
authors.initials: ES
authors.lastname: Dellon
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D004724:Endoscopy; D057765:Eosinophilic Esophagitis / Q000175:diagnosis / Q000453:epidemiology*; D004804:Eosinophils / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012621:Seasons