Incidence of inflammatory bowel disease in north west Greece: rarity of Crohn's disease in an area where ulcerative colitis is common

Ulcerative colitis (UC) and Crohn's disease (CD) are generally regarded as diseases of affluent societies of the Western World, although their frequency in less affluent areas is not well established. This retrospective study therefore, assesses the incidence of UC and CD in a semirural area of north west Greece during the 10 year period 1982-1991. By the 31 December 1991, 61 patients had met standard diagnostic criteria for UC (annual incidence 4.0/10(5), 95% confidence intervals 3.0 to 5.0/10(5)) and only five patients met the diagnostic criteria for CD (annual incidence 0.3/10(5), 95% confidence intervals 0.1 to 0.8/10(5)) in this area of 157,214 inhabitants. UC incidence was lowest in the first three years at 1.8/10(5) per annum and subsequently increased to 4.8 and 5.1/10(5) per annum for the successive four and three year periods respectively. UC incidence was slightly higher in men. A third of all cases of UC had pancolitis while a quarter had only proctitis. More than one half were categorised as having moderate or severe colitis. Three quarters of the patients resided in urban areas. The incidence of CD was a twelfth of the UC incidence, which is in considerable contrast with most Western countries where the incidence of CD is usually no less than a third that for UC. The rarity of CD points to the absence of aetiological environmental factors specific for CD.