Comparing Environmental Risk Factors at Diagnosis in Faroese and Danish Patients with Inflammatory Bowel Disease.

Background: The incidence and prevalence of inflammatory bowel disease (IBD) in the Faroe Islands have increased drastically during the past 60 years, presumably due to changing environmental risk factors in a genetically susceptible population.

Aim: This study investigated differing environmental factors present in Faroese and Danish patients.

Methods: From 2010 to 2022, all incident Faroese patients with IBD were invited to complete the International Organization of IBD (IOIBD) questionnaire about environmental factors at the time of their diagnosis. The findings were compared to a cohort of incident Danish patients diagnosed between 2010 and 2011.

Results: Questionnaires were completed by 293 of 388 Faroese patients (75%), of whom 15% (n = 45) had Crohn's disease (CD), 63% (n = 185) had ulcerative colitis (UC), and 22% (n = 63) had IBD unclassified (IBDU). Faroese patients with IBD and UC were found to have higher pertussis vaccination coverage (p < 0.05), and more childhood infections of measles and pertussis (p < 0.05). Faroese patients with IBD consumed more fast food and less fiber but consumed less sugar (p < 0.001) and more caffeine (p < 0.001). No differences were found regarding gender, having been breastfed, use of oral contraceptives, or the number of first-degree relatives with IBD; however, differences in smoking at diagnosis were found in a subset analysis of Faroese patients diagnosed in 2010-11 compared with Danish patients.

Conclusions: Faroese patients with IBD were more exposed to some environmental risk factors prior to diagnosis than Danish patients. However, certain beneficial dietary habits were more common in Faroese patients than in Danish patients.