title: Inflammatory Bowel Disease Environmental Risk Factors: A Population-Based Case-Control Study of Middle Eastern Migration to Australia.
abstract: OBJECTIVE
  The incidences of the inflammatory bowel diseases (IBDs) Crohn's disease (CD) and ulcerative colitis (UC) are increasing, indicating gene-environment interactions. Migrants from low-IBD-prevalence countries to a high-prevalence country may help identify the relative contribution of environmental risk factors compared with native Caucasians.
  
  
  METHODS
  This prospective case-control study evaluated IBD environmental risk factors of Middle Eastern migrants (MEM) in Australia compared with matched Caucasian IBD subjects, MEM controls, Caucasian controls, and controls in the Middle East using adjusted odds ratios (aOR).
  
  
  RESULTS
  A total of 795 subjects were recruited: 154 MEM cases (75 CD; 79 UC), 153 MEM controls, 162 Caucasian cases (85 CD; 77 UC), 173 Caucasian controls, and 153 controls in Lebanon. Smoking increased CD risk in MEM and Caucasians and reduced UC risk in Caucasians (aOR, 0.77; 95% CI, 0.41-0.98) but not MEM (aOR, 1.45; 95% CI, 0.80-2.62). Antibiotic use reduced the risk of MEM CD (aOR, 0.27; 95% CI, 0.11-0.67) and UC (aOR, 0.38; 95% CI, 0.18-0.80), but increased the risk in Caucasians (CD: aOR, 5.24; 95% CI, 2.13-12.90; and UC: aOR, 6.82; 95% CI, 2.67-17.38). Most hygiene markers (rural dwelling, pet ownership, pet feeding, and farm animal contact) reduced CD and UC risk in MEM (P < .05). In contrast, in Caucasians these hygiene markers lacked significance. Other significant risk factors include IBD family history, appendectomy, tonsillectomy, and breastfeeding.
  
  
  CONCLUSIONS
  Differential IBD environmental risk factors exist between migrants and native Caucasians, indicating a dynamic interplay between environmental factors and IBD risk for immigrants that is distinct to those factors most relevant in native Caucasians.
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; Gastroenterology and Liver Services, Bankstown Hospital, Sydney, Australia; Faculty of Medicine, UNSW Australia.
authors.forename: Yanna
authors.initials: Y
authors.lastname: Ko
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; Gastroenterology and Liver Services, Bankstown Hospital, Sydney, Australia.
authors.forename: Viraj
authors.initials: V
authors.lastname: Kariyawasam
authors.affiliation: American University of Beirut Medical Center, Beirut, Lebanon.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Karnib
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; Gastroenterology and Liver Services, Bankstown Hospital, Sydney, Australia.
authors.forename: Rhys
authors.initials: R
authors.lastname: Butcher
authors.affiliation: Gastroenterology and Liver Services, Bankstown Hospital, Sydney, Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Douglas
authors.initials: D
authors.lastname: Samuel
authors.affiliation: Gastroenterology and Liver Services, Bankstown Hospital, Sydney, Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Alrubaie
authors.affiliation: Gastroenterology and Liver Services, Bankstown Hospital, Sydney, Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Nabil
authors.initials: N
authors.lastname: Rahme
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Charles
authors.initials: C
authors.lastname: McDonald
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: James
authors.initials: J
authors.lastname: Cowlishaw
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Katelaris
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Gavin
authors.initials: G
authors.lastname: Barr
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Brian
authors.initials: B
authors.lastname: Jones
authors.affiliation: Department of Gastroenterology and Hepatology, Liverpool Hospital, Sydney, New South Wales, Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Susan
authors.initials: S
authors.lastname: Connor
authors.affiliation: Department of Gastroenterology and Hepatology, St George Hospital, Kogarah, New South Wales, Australia.
authors.forename: Gokulan
authors.initials: G
authors.lastname: Paven
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; Faculty of Medicine, UNSW Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Grace
authors.initials: G
authors.lastname: Chapman
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; Faculty of Medicine, UNSW Australia; IBD Sydney Organisation, Sydney, Australia.
authors.forename: Gordon
authors.initials: G
authors.lastname: Park
authors.affiliation: Faculty of Medicine, University of Otago, Christchurch, New Zealand.
authors.forename: Richard
authors.initials: R
authors.lastname: Gearry
authors.affiliation: Gastroenterology and Liver Services, Concord Hospital, Sydney, Australia; Gastroenterology and Liver Services, Bankstown Hospital, Sydney, Australia; Faculty of Medicine, UNSW Australia; IBD Sydney Organisation, Sydney, Australia. Electronic address: rupertleong@outlook.com.
authors.forename: Rupert W
authors.initials: RW
authors.lastname: Leong
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001315:Australia / Q000453:epidemiology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D008877:Middle East / Q000453:epidemiology; D011446:Prospective Studies; D044469:Racial Groups; D012307:Risk Factors; D014171:Transients and Migrants; D055815:Young Adult
keywords: Environmental; Hygiene Hypothesis; Inflammatory Bowel Disease; Migrants; Risk Factors