title: Seasonality and pediatric inflammatory bowel disease.
abstract: OBJECTIVE
  Seasonal and geographic variations of inflammatory bowel disease (IBD) exacerbations have been described in adults, with inconsistent findings. We sought to determine whether disease activity in pediatric-onset IBD is associated with a seasonal pattern.
  
  
  METHODS
  We examined children with Crohn disease (CD) and ulcerative colitis (UC) using data from the ImproveCareNow Collaborative between December 2008 and November 2010. We compared the proportion of patients in continuous remission for all recorded visits in each season. We also compared the distribution of all recorded visits with a physician global assessment (PGA) of remission or active disease across seasons.
  
  
  RESULTS
  A total of 1325 patients with CD (6102 visits) and 587 patients with UC (2394 visits) were included. The proportion of patients with UC in continuous remission during each season was highest in the summer (67%) and lowest in the winter (55%) (P=0.01). A similar pattern was found for CD but was not significant. Similarly, the proportion of visits in remission was highest in the summer and lowest in the winter for both UC (29%, 21%; P<0.001) and CD (28%, 23%; P<0.001); however, the distribution of visits with active disease was not significantly different across seasons.
  
  
  CONCLUSIONS
  The higher proportion of patients with UC in continuous remission in the summer may be related to the higher proportion of remission visits in the summer, because the proportion of visits with active disease was similar across seasons. These findings do not support any strong associations between season of the year and disease activity in pediatric IBD.
authors.affiliation: *Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Nationwide Children's Hospital, Columbus, OH †Division of Gastroenterology and Hepatology, Department of Pediatrics, University of North Carolina at Chapel Hill ‡Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH §Department of Pediatrics, University of Vermont, Burlington ||Department of Pediatrics, Nationwide Children's Hospital/Ohio State University, Columbus.
authors.forename: Grace J
authors.initials: GJ
authors.lastname: Lee
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Dotson
authors.forename: Michael D
authors.initials: MD
authors.lastname: Kappelman
authors.forename: Eileen
authors.initials: E
authors.lastname: King
authors.forename: Jesse M
authors.initials: JM
authors.lastname: Pratt
authors.forename: Richard B
authors.initials: RB
authors.lastname: Colletti
authors.forename: Sarah
authors.initials: S
authors.lastname: Bistrick
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Burkam
authors.forename: Wallace V
authors.initials: WV
authors.lastname: Crandall
mesh_terms: D000293:Adolescent; D002648:Child; D003093:Colitis, Ulcerative / Q000145:classification* / Q000188:drug therapy; D003424:Crohn Disease / Q000145:classification* / Q000188:drug therapy; D005260:Female; D006801:Humans; D008297:Male; D009819:Office Visits / Q000706:statistics & numerical data*; D012621:Seasons; D012720:Severity of Illness Index