title: Environmental risk factors in inflammatory bowel disease: a population-based case-control study in Asia-Pacific.
abstract: OBJECTIVE
  The rising incidence of inflammatory bowel disease in Asia supports the importance of environmental risk factors in disease aetiology. This prospective population-based case-control study in Asia-Pacific examined risk factors prior to patients developing IBD.
  
  
  METHODS
  442 incident cases (186 Crohn's disease (CD); 256 UC; 374 Asians) diagnosed between 2011 and 2013 from eight countries in Asia and Australia and 940 controls (frequency-matched by sex, age and geographical location; 789 Asians) completed an environmental factor questionnaire at diagnosis. Unconditional logistic regression models were used to estimate adjusted ORs (aOR) and 95% CIs.
  
  
  RESULTS
  In multivariate model, being breast fed >12 months (aOR 0.10; 95% CI 0.04 to 0.30), antibiotic use (aOR 0.19; 0.07 to 0.52), having dogs (aOR 0.54; 0.35 to 0.83), daily tea consumption (aOR 0.62; 0.43 to 0.91) and daily physical activity (aOR 0.58; 0.35 to 0.96) decreased the odds for CD in Asians. In UC, being breast fed >12 months (aOR 0.16; 0.08 to 0.31), antibiotic use (aOR 0.48; 0.27 to 0.87), daily tea (aOR 0.63; 0.46 to 0.86) or coffee consumption (aOR 0.51; 0.36 to 0.72), presence of hot water tap (aOR 0.65; 0.46 to 0.91) and flush toilet in childhood (aOR 0.71; 0.51 to 0.98) were protective for UC development whereas ex-smoking (aOR 2.02; 1.22 to 3.35) increased the risk of UC.
  
  
  CONCLUSIONS
  This first population-based study of IBD risk factors in Asia-Pacific supports the importance of childhood immunological, hygiene and dietary factors in the development of IBD, suggesting that markers of altered intestinal microbiota may modulate risk of IBD later in life.
authors.affiliation: Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Institute of Digestive Disease, Li Ka Shing Institute of Health Science, Hong Kong, China.
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authors.initials: SC
authors.lastname: Ng
authors.affiliation: Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Institute of Digestive Disease, Li Ka Shing Institute of Health Science, Hong Kong, China.
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authors.affiliation: St Vincent's Hospital, University of Melbourne, Melbourne, Victoria, Australia Imperial College London, London, UK.
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authors.affiliation: Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.
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authors.affiliation: Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.
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authors.affiliation: Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.
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authors.affiliation: National University Hospital of Singapore, Singapore, Singapore.
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authors.affiliation: University of Malaya Medical Center, Kuala Lumpur, Malaysia.
authors.forename: Khean Lee
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authors.affiliation: West China Hospital, Sichuan University, Chengdu, China.
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authors.affiliation: The First Affiliated Hospital of San Yat Sen University, Guangzhou, China.
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authors.affiliation: The First Affiliated Hospital of San Yat Sen University, Guangzhou, China.
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authors.affiliation: King Chulalongkorn Memorial Hospital, Bangkok, Thailand.
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authors.affiliation: University of Indonesia, Indonesia, Indonesia.
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authors.affiliation: University of Indonesia, Indonesia, Indonesia.
authors.forename: Murdani
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authors.affiliation: Tseung Kwan O Hospital, Hong Kong, Hong Kong.
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authors.affiliation: Alice Ho Miu Ling Nethersole Hospital, Hong Kong, Hong Kong.
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authors.affiliation: Department of Pediatrics, Chinese University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Chung Mo
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authors.affiliation: Kiangwu Hospital, Macao, China.
authors.forename: Hon Ho
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authors.affiliation: Kiangwu Hospital, Macao, China.
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authors.forename: Ka Kei
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authors.affiliation: Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Institute of Digestive Disease, Li Ka Shing Institute of Health Science, Hong Kong, China.
authors.forename: Jessica
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authors.lastname: Ching
authors.affiliation: Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Institute of Digestive Disease, Li Ka Shing Institute of Health Science, Hong Kong, China.
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authors.initials: JC
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authors.affiliation: Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Institute of Digestive Disease, Li Ka Shing Institute of Health Science, Hong Kong, China.
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authors.initials: FK
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authors.affiliation: Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Institute of Digestive Disease, Li Ka Shing Institute of Health Science, Hong Kong, China.
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mesh_terms: D000328:Adult; D001208:Asia / Q000453:epidemiology; D001315:Australia / Q000453:epidemiology; D001942:Breast Feeding; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D015994:Incidence; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology*; D007422:Intestines / Q000382:microbiology; D008297:Male; D064307:Microbiota; D008875:Middle Aged; D015999:Multivariate Analysis; D057805:Pets; D011446:Prospective Studies; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology
keywords: CROHN'S DISEASE; EPIDEMIOLOGY; IBD; ULCERATIVE COLITIS