title: Solar radiation is inversely associated with inflammatory bowel disease admissions.
abstract: OBJECTIVE
  To explore the associations between latitude and solar radiation with inflammatory bowel disease admission rates in Chile, the country with the largest variation in solar radiation in the world.
  
  
  METHODS
  This is an ecological study, which included data on all hospital-admitted population for inflammatory bowel disease between 2001 and 2012, according to different latitudes and solar radiation exposures in Chile. The data were acquired from the national hospital discharge database from the Department of Health Statistics and Information of the Chilean Ministry of Health.
  
  
  RESULTS
  Between 2001 and 2012 there were 12,869 admissions due to inflammatory bowel disease (69% ulcerative colitis, 31% Crohn's disease). Median age was 36 years (IQR: 25-51); 57% were female. The national inflammatory bowel disease admission rate was 6.52 (95% CI: 6.40-6.63) per 100,000 inhabitants with increasing rates over the 12-year period. In terms of latitude, the highest admission rates for pediatric ulcerative colitis and Crohn's disease, as well as adult ulcerative colitis, were observed in the southernmost region with lowest annual solar radiation. Linear regression analysis showed that regional solar radiation was inversely associated with inflammatory bowel disease admissions in Chile (β: -.44, p = .03).
  
  
  CONCLUSIONS
  Regional solar radiation was inversely associated with inflammatory bowel disease admission rates in Chile; inflammatory bowel disease admissions were highest in the southernmost region with lowest solar radiation. Our results support the potential role of vitamin D deficiency on inflammatory bowel disease flares.
authors.affiliation: a Department of Pediatric Gastroenterology and Nutrition , School of Medicine, Pontificia Universidad Católica de Chile , Santiago , Chile.
authors.forename: Francisca
authors.initials: F
authors.lastname: Jaime
authors.affiliation: a Department of Pediatric Gastroenterology and Nutrition , School of Medicine, Pontificia Universidad Católica de Chile , Santiago , Chile.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Riutort
authors.affiliation: b Department of Gastroenterology , School of Medicine, Pontificia Universidad Católica de Chile , Santiago , Chile.
authors.forename: Manuel
authors.initials: M
authors.lastname: Alvarez-Lobos
authors.affiliation: c Department of Pediatric Infectious Diseases and Immunology , School of Medicine, Pontificia Universidad Católica de Chile , Santiago , Chile.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Hoyos-Bachiloglu
authors.affiliation: d Department of Emergency Medicine and Division of Rheumatology, Allergy, and Immunology, Department of Medicine , Massachusetts General Hospital, Harvard Medical School , Boston , MA , USA.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
authors.affiliation: c Department of Pediatric Infectious Diseases and Immunology , School of Medicine, Pontificia Universidad Católica de Chile , Santiago , Chile.|e Millennium Institute on Immunology and Immunotherapy , School of Medicine, Pontificia Universidad Católica de Chile , Santiago , Chile.
authors.forename: Arturo
authors.initials: A
authors.lastname: Borzutzky
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002677:Chile / Q000453:epidemiology; D003093:Colitis, Ulcerative / Q000453:epidemiology*; D003424:Crohn Disease / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010343:Patient Admission / Q000706:statistics & numerical data*; D012042:Registries; D012621:Seasons; D017678:Sex Distribution; D013472:Sunlight; D014808:Vitamin D Deficiency / Q000453:epidemiology / Q000209:etiology; D055815:Young Adult
keywords: Crohn’s disease; Inflammatory bowel disease; admissions; flares; latitude; solar radiation; ulcerative colitis; vitamin D