Authors: Bjornsson S, Johannsson JH.

Institution: Department of Medicine, Reykjavik Hospital, Iceland.

Background: Two separate nationwide, retrospective epidemiological studies of inflammatory bowel disease (IBD) in Iceland over a combined 40-year period, 1950-1989, have shown a continually rising incidence. The main objective of this study was to investigate the incidence of IBD prospectively for the 5-year period 1990-1994 to determine whether there still was an ongoing increase.

Results: A total of 215 cases of UC and 72 cases of CD were diagnosed, yielding a mean annual incidence for UC 16.5/100000 (95% confidence interval (CI) 14.4-18.9), and for CD 5.5/100000 (95% CI 4.3-7.0). The highest combined age related incidence for UC was 28.7/100000 in the group aged 30-39 years, and for CD 8.5/100000 in the groups aged 10-19 and 20-29 years. The most common extent in UC was proctosigmoid and the most frequent localization in CD was colonic only.

Conclusions: This prospective study demonstrates a continuing and statistically significant increase in the incidence of both UC and CD in Iceland. The general changes identified for a few previously suggested environmental factors do not allow any firm conclusions as to their role in the observed increase in incidence. It is possible that there are some other causative factor(s).

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10656207&query_hl=19

• Change in Incidence of Crohn's Disease and Ulcerative Colitis in Denmark. A Study Based on the National Registry of Patients, 1981-1992
• Inflammatory Bowel Disease in Iceland, 1990-1994: a Prospective, Nationwide, Epidemiological Study
• Inflammatory Bowel Disease in Iceland, 1980-89. A Retrospective Nationwide Epidemiologic Study
• Incidence and Prevalence of Ulcerative Colitis and Crohn's Disease in Urban and Rural Areas of Spain from 1981 to 1988