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Gut. 2007 November; 56(11): 1638–1639.
PMCID: PMC2095671

Inflammatory bowel disease: reviewing an old study under a new perspective

We would like to comment on the paper by Professor S Shivananda and colleagues (Gut 1996;39:690–7), which examined whether there was a difference in the incidence of inflammatory bowel disease (IBD) between northern and southern Europe.

Shivananda et al. conducted an epidemiological study across Europe from 1991 to 1993, and concluded that IBD, which includes ulcerative colitis (UC) and Crohn's disease (CD), is possibly not more frequent in the north than in the south.

Although their results are solid and groundbreaking, they did not manage to provide an explanation of the geographic distribution of the disease. A possible reason is that they did not include countries from Eastern Europe in their study.

Recent data from this area give us the opportunity to examine this issue again, providing a possible explanation. In fig 11,, we present the incidence of UC (fig 1A1A)) and CD (fig 1B1B)) across Europe, according to data mentioned in reviews by Lakatos and Lakatos,1 and Loftus.2 We note some characteristics that are the basis for the new explanation:

figure gt132688.f1
Figure 1 Incidence of IBD across Europe. (A) Incidence of ulcerative colitis (UC). (B) Incidence of Crohn's disease (CD). The maps were designed with Philcarto 4.50 for Windows (http://perso.club‐internet.fr/philgeo).
  • Although Estonia is located in northern Europe, the incidence of IBD shows pronounced differences compared with the high incidence in Scandinavian countries.1
  • Estonia, Hungary, Romania, Croatia, the Czech Republic, Slovakia and Poland have incidence rates of UC that range from 0.5 to 5.9 per 100 000 population1 while countries of Western Europe have an overall incidence for UC of (at least) 10.4 (Gut 1996;39:690–7). For CD, the incidence rates of the previously mentioned countries of Eastern Europe range from 0.1 to 5.7,1 whereas countries of Western Europe have an overall incidence no less than 5.6 (Gut 1996;39:690–7).
  • The countries of Eastern Europe are mainly less developed than the countries of Western Europe.3

Thus, is there a developed–developing gradient? The authors believe that it might be so. The development gradient is consistent with the aetiological cause of “westernisation” in the expression of IBD, since more developed countries are generally more westernised. Westernised lifestyle means increased consumption of refined sugar, fatty acids, fast food, cereals and bread and reduced consumption of fruit, vegetables and fibre. Furthermore, indoor and sedentary occupations as well as improved sanitation are common characteristics of westernised cultures. For all of these aspects of westernisation, there have been noted associations with IBD.4,5

Therefore, we can see that IBD can be better distributed according to the development of countries, instead of the north–south gradient. The underlying cause for such a distribution could be westernisation, which coincidentally explains the increase of the incidence observed in some countries (eg, according to this hypothesis, we could say that the incidence of IBD has increased in Hungary over the last few years because it has become more westernised since its level of development has risen3). This possible association of a wealth factor, such as the development level, with the incidence of IBD, has been noted by Ekbom, who mentions a possible influence of wealth on the incidence of IBD: “The disappearance of the north–south gradient in Europe might be an illustration of what will happen when society gains affluence. It is therefore of extreme interest to follow the temporal trends for IBD in Eastern Europe.”6 Similar comments have been made by other reviewers.4,5 Finally, this theory is furthermore consistent with observations about other diseases such as type I diabetes and multiple sclerosis.7 Specifically, Patterson et al.8 note for type I diabetes that “the strikingly higher incidence in Finland compared to ethnically‐similar sub‐populations in Estonia as well as the apparent decrease in type I diabetes in Germany could reflect wealth‐related risk factors.”

All these observations together allow us to suppose such a distribution of IBD, an issue that would be an interesting subject of research.

Footnotes

Competing interests: None declared.

References

1. Lakatos L, Lakatos P L. Is the incidence and prevalence of inflammatory bowel diseases increasing in Eastern Europe? Postgrad Med J 2006. 82332–337.337 [PMC free article] [PubMed]
2. Loftus E V., Jr Clinical epidemiology of inflammatory bowel disease: incidence, prevalence, and environmental influences. Gastroenterology 2004. 1261504–1517.1517 [PubMed]
3. The World Bank Country Classification 2007. http://www.worldbank.org/data/countryclass/classgroups.htm#High_income (accessed 16 June 2007)
4. Hanauer S B. Inflammatory bowel disease: epidemiology, pathogenesis, and therapeutic opportunities. Inflamm Bowel Dis 2006. 12(Suppl 1)S3–S9.S9 [PubMed]
5. Krishnan A, Korzenik J R. Inflammatory bowel disease and environmental influences. Gastroenterol Clin North Am 2002. 3121–39.39 [PubMed]
6. Ekbom A. The changing faces of Crohn's disease and ulcerative colitis. In: Targan SR, Shanahan F, Karp LC, eds. Inflammatory bowel disease: from bench to bedside. New York: Springer, 2005. 5–20.20
7. Bach J F. The effect of infections on susceptibility to autoimmune and allergic diseases. N Engl J Med 2002. 347911–920.920 [PubMed]
8. Patterson C C, Dahlquist G, Soltész G. et al Is childhood‐onset Type I diabetes a wealth‐related disease? An ecological analysis of European incidence rates. Diabetologia 2001. 44(Suppl 3)B9–B16.B16 [PubMed]

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