Descriptive epidemiology is the study of the incidence (number of new cases per year per 10⁵ inhabitants), prevalence (total number of cases per 10⁵ inhabitants at a given time), temporal evolution of these two parameters and demographic factors, such as age at onset of the disease, gender and ethnic variations. More in-depth knowledge of the descriptive epidemiology of IBD (inflammatory bowel diseases) and, in particular, differences in prevalence with respect to age and geographic distribution, could orient research toward etiological factors.

Initial data on the incidence of IBD in France date from the end of the 1980s. The first epidemiological study to be carried out, the EPIMAD registry, was begun in 1988 in northwestern France, and to date, it is the largest international study on a general population (5,790,526 inhabitants).

In the northwest of France between 1988 and 2007, the incidence of Crohn’s disease (CD) increased from 5.2 in 1988-90 to 7.1 in 1997-99 and then became stable at 6.7 in 2006-2007 (an increase of 29%).

More detailed analyses revealed that this increase was primarily due to a sharp rise in figures in the 10-19-year-old age group, where the incidence increased by 79% during that same period.  Similar results have been observed in Norway, Scotland, Finland, Sweden, Australia and Canada.

These results should help to focus on that particular population, via analytical epidemiological studies and a search for risk factors.

References

Aliment Pharmacol. Ther 2011; 33: 1133-1142.