Background and objectives: Incidence and prevalence of Inflammatory Bowel Disease (IBD) differ considerably depending on the geographical region studied. In Spain, both Ulcerative Colitis (UC) and Crohn's Disease (CD) seem to have experienced an important change in terms of incidence during the past decades. Our aim was to systematically review the experience in Spain regarding the epidemiology of IBD, in particular its incidence, its geographical differences and its evolution over time.
Methods: A bibliographical search till January 2000 was conducted in Internet using the PubMed search motor and the following descriptors or key words: "Crohn's disease", "Ulcerative colitis", "Inflammatory bowel disease", "Spain" and "Spanish". Only publications providing data on IBD incidence among Spanish patients were included. References from articles that fulfilled the selection criteria were also reviewed. The endpoints considered in the review were IBD incidence rate, its geographical differences, and its evolution over time.
Results: UC incidence reported by different studies performed in Spain ranges from 0.6 to 8 cases/10(5)/year, with a mean value of 3.8. CD incidence rates in Spain ranges from 0.4 to 5.5 cases/105/year, with a mean value of 1.9. Some studies have shown differences in IBD incidence between regions in our country. Many studies have reported an increase in IBD incidence in Spain over time, although such increase is more evident in the case of CD.
Conclusions: UC incidence in Spain ranges from 0.6 to 8 cases/105/year, with a mean value of 3.8. CD figures range from 0.4 to 5.5 cases/105/year, with an average rate of 1.9. IBD incidence seems to be relatively different depending on the geographical region studied. Finally, several authors have demonstrated an increase in IBD incidence in Spain over time, although such increase seems to be more evident in the case of CD. Consequently, IBD in Spain is no longer considered a rare disease, but a relatively frequent one.