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P622. Smoking, breastfeeding, physical inactivity, contact with animals, and size of the family influence the risk of inflammatory bowel diseases in a Slovak case-control study

T. Hlavaty1, J. Toth1, T. Koller1, A. Krajcovicova1, S. Oravcova1, Z. Zelinkova1, M. Huorka1, 1University hospital Bratislava, Bratislava, Slovakia


The aetiology of inflammatory bowel disease (IBD) is not known but is likely to involve a combination of genetic predisposition and environmental risk factors. Smoking has been associated consistently with a higher risk of Crohn's disease (CD), while appendectomy and smoking appear to diminish the risk of ulcerative colitis (UC). The roles of other environmental factors are unclear. The aim of this study was to investigate associations between environmental risk factors and CD and UC by multivariate analysis.


This case-control study included 362 patients with IBD (190 with CD, 148 with UC, 24 with indeterminate colitis) and 355 controls. All subjects completed a detailed questionnaire consisting of 44 questions concerning socio-economic status, medical and surgical history, and exposure to environmental risk factors, including the length of the breastfeeding period, the history of helminth infections, allergic diseases, and appendectomy, the size of the household, the type of housing, the contact with particular domestic animals, physical activity, and smoking. The association of these factors with CD and UC were tested by univariate and multivariate analyses.


Multivariate analysis revealed that CD associated with smoking at diagnosis (Odds ratio [OR] 3.7, 95% confidence intervals [CI] 2.2–6.2; p < 0.001), being breastfed for less than 6 months (OR 2.7, 95% CI 1.7–4.4; p < 0.001), less than two sporting activities per week in childhood (OR 2.7, 95% CI 1.5–5.0; p < 0.001), and frequent contact with cats in childhood (OR 1.7, 95% CI 1.1–2.8; p < 0.03). UC associated with fewer than two sporting weekly activities in childhood (OR 2.0, 95% CI 1.1–3.6, p = 0.02), the number of household members in childhood (OR 0.8, 95% CI 0.7–0.98, p = 0.03), and being breastfed for less than 6 months (OR 1.7, 95% CI 1.02–2.8, p = 0.04). A composite environmental risk index (ERI) was proposed for CD. Use of this index revealed that 47% of the controls but only 14% of patients with CD had no risk factors, while 14% of the controls and 38% of the patients with CD had at least two risk factors.


CD and UC associated with infrequent sports activities in childhood and a short breastfeeding period. CD also associated with smoking and infrequent contact with animals in childhood. UC also associated with a smaller family size in childhood.