• O Niewiadomski, C Studd, J Wilson, J Williams, C Hair, R Knight, E Prewett, P Dabkowski, S Alexander, B Allen, D Dowling, W Connell, P Desmond, and S Bell.
• Department of Gastroenterology, The University of Melbourne, St Vincent's Hospital, Melbourne, Victoria, Australia.
• Intern Med J. 2016 Jun 1; 46 (6): 669-76.

BackgroundThe Barwon area in Australia has one of the highest incidence rates of inflammatory bowel disease (IBD) and therefore is an ideal location to study the impact of environmental exposures on the disease's development.AimTo study these exposures prior to the development of IBD in a population-based cohort.MethodOne hundred and thirty-two incident cases (81 Crohn disease (CD) and 51 ulcerative colitis (UC)) from an IBD registry and 104 controls replied to the International Organization of Inflammatory Bowel Diseases environmental questionnaire. This included 87 questions about pre-illness exposures that included childhood illnesses, vaccinations, breastfeeding, house amenities, pets and swimming, diet and smoking.ResultsThe factors associated with CD included smoking (odds ratio (OR): 1.42, confidence interval (CI): 1-2.02, P = 0.029); childhood events, including tonsillectomy (OR: 1.74, CI: 1.15-2.6, P = 0.003) and chicken pox infection (OR: 3.89, CI: 1.61-9.4, P = 0.005) and pre-diagnosis intake of frequent fast food (OR: 2.26, CI: 1.76-4.33, P = 0.003). In UC, the risk factors included smoking (OR: 1.39, CI: 1.1-1.92, P = 0.026) and pre-diagnosis intake of frequent fast food (OR: 2.91, CI: 1.54-5.58, P < 0.001), and high caffeine intake was protective (OR: 0.51, 95% CI: 0.3-0.87, P = 0.002). Other protective exposures for UC included high fruit intake (OR: 0.59, CI: 0.4-0.88, P = 0.003) and having pets as a child (OR: 0.36, CI: 0.2-0.79, P = 0.001).ConclusionThis first Australian population-based study of environmental risk factors confirms that smoking, childhood immunological events and dietary factors play a role in IBD development; while high caffeine intake and pet ownership offer a protective effect.© 2016 Royal Australasian College of Physicians.

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