The Faroese IBD Study: Incidence of Inflammatory Bowel Diseases Across 54 Years of Population-based Data

Abstract

Background and Aims:Inflammatory bowel diseases [IBDs] include Crohn’s disease [CD], ulcerative colitis [UC], and IBD unclassified [IBDU]. In 2010 and 2011, the ECCO-EpiCom study found the worldwide highest incidence of inflammatory bowel disease [IBD] in the Faroe Islands: 83 per 100 000 [European Standard Population, ESP]. The present study assessed the long-term time trends in IBD incidence in the Faroese population.Methods:In this population-based study, data were retrieved from the National Hospital of the Faroe Islands and included all incident cases of CD, UC, and IBDU diagnosed between July 1960 and July 2014. Patients of all ages were included and diagnoses were defined according to the Copenhagen Diagnostic Criteria.Results:A total of 664 incident IBD patients were diagnosed: 113 with CD, 417 with UC, and 134 with IBDU. Of these, 51 [8%] were diagnosed with paediatric-onset IBD. Between 1960 and 1979, a total of 55 persons were diagnosed; 105 in 1980–89; 166 in 1990–99; 180 in 2000–09; and 158 in 2010–14. This represented an increase in the age-standardised IBD incidence rate from 7, 25, 40, and 42 to 74 per 100 000 [ESP]. For CD, the increase was from 1 to 10, for UC from 4 to 44, and for IBDU from 2 to 21 per 100 000 [ESP].Conclusions:The high IBD incidence was found to be a relatively new phenomenon. The observed increase is unlikely to be an artefact resulting from, for instance, better registration. Our study indicated a real and increasing disease burden resulting from changing—so far unidentified—exposures.

The incidence of inflammatory bowel disease in Denmark 1980–2013: a nationwide cohort study

“…Our findings confirm that the incidence of IBD continues to increase in Denmark. This finding is in accordance with recent observations in other high‐incidence areas such as France, Spain, Canada and our neighbouring Scandinavian countries, as well as in previous low‐incidence areas of Eastern Europe and Asia …”

Inflammatory bowel diseases in Faroese‐born Danish residents and their offspring: further evidence of the dominant role of environmental factors in IBD development

“…It is noteworthy that in our previous study of time trends in IBD incidence in the Faroe Islands, we found a rapid increase over time in the UC incidence, while the trend for CD incidence showed a more modest increase. Furthermore, for CD patients’ disease was primarily located in the colon (L2) and the average age at onset is higher in the Faroe Islands than in the rest of Europe . IBD is believed to occur in genetically pre‐disposed individuals .…”

“…However, genetics alone cannot explain the recent steep increase in IBD incidence in the Faroe Islands . Differences in diet are considered to be the most topical and likely factors in explaining the geographical variation and rising incidence of IBD .…”

“…The ECCO‐EpiCom age‐standardised rate (European Standard Population) was 24 per 100 000 for Denmark, while this rate was 45 per 100 000 in our data. For this reason, we were not able to compare our IBD incidence data for the immigrants with the available rates from the Faroese population, as these rates were generated based on the Copenhagen Diagnostic Criteria . This reflects the inaccuracy of using the routine hospital discharge diagnosis.…”

“…However, given that the introduction of an exposure is associated with an increased risk of a disease, a stronger support for the causation hypothesis may be revealed, if the risk of the disease also decreases once the exposure ceases . The IBD incidence has increased in the Faroe Islands during the past 50 years . In this respect, the development in the Faroe Islands resembles that of other countries undergoing Westernisation .…”