P749 Early environmental and lifestyle factors are associated with developing inflammatory bowel disease

The aetiology of inflammatory bowel disease (IBD), consisting of Crohn's disease (CD) and ulcerative colitis (UC), is complex with an interplay between genomic susceptibility, diet, microbiome and environmental factors. Differences in findings between studied populations are large, and it is likely that a large number of involved factors are unknown, while identification of modifiable risk factors is crucial. We executed a large population-based study evaluating known and possibly involved environmental factors. IBD patients (n = 674) of the University Medical Center Groningen, the Netherlands, were asked to fill the validated Groningen IBD Environmental Questionnaire (GIEQ). [1] Here, we focus on 19 lifestyle factors. Patients were randomly matched based on age at diagnosis and sex to controls (1 to 2 case–control ratio) from the population-based LifeLines cohort study, who completed a comparable questionnaire. Logistic regression was applied to estimate the multivariable-adjusted effect of lifestyle factors on IBD (odds ratio; OR) and 95% confidence intervals. All models were corrected for age, sex and history of smoking. A p < 0.05 was considered as nominal and a Bonferroni adjusted p-value < 0.0026 as statistically significant. CD and UC patients had high odds of being exposed to prenatal smoke exposure (OR1.9, 95% CI 1.4–2.6; 1.6, 1.2–2.2). CD patients were also more often former or current smokers (1.5, 1.0–2.2; 2.6, 2.0–3.4) than controls. The presence of more than three stressful life-events prior to diagnosis also increased risk of CD and UC (2.9, 1.9–4.5; 2.6, 1.7-4.0). Patients with IBD less often had a childhood cat or dog, with the strongest effect during the first year of life (all p-values < 0.00026). Also, patients less often used alcoholic beverages than controls yielding a protective OR for both diseases, red wine being the most protective factor in CD (0.3, 0.2–0.7). Table 1. Multi-variate-adjusted logistic regression models of the role of the early life exposures in risk of IBD development. Table 2. Multi-variate adjusted logistic regression models of the role of lifestyle at diagnosis in risk of IBD development. A history of prenatal smoking and stress was associated with increased risk of IBD, whereas a history of a childhood cat or dog was associated with a lower risk of IBD. Identification of modifiable factors in the aetiology of IBD is crucial, especially for individuals at risk. Future studies are needed to confirm these findings and proof its applicability on risk reduction management of IBD. Reference 1. van der Sloot K, Weersma R, Dijkstra G et al.Development and validation of a web-based questionnaire to identify environmental risk factors for inflammatory bowel disease. J Gastroenterol 2018. doi:10.1007/s00535-018-1501-z