Crohn's disease in Wales, 1967-1976; an epidemiological survey based on hospital admissions.

One thousand and ninety-eight patients from Wales were treated in hospital for Crohn's disease between 1967 and 1976, which gave an overall 'period prevalence' for the disease of 40 cases/10(5) of the total population. The data were analysed for each of the 8 counties and for rural as well as urban populations of different sizes. The disease was significantly more common in the urban counties of Gwent and the 3 parts of Glamorgan compared with the remainder of Wales. The highest prevalence was in South Glamorgan (54 cases/10(5)) and the lowest in Dyfed (30/10(5)). There was a relatively small but highly significant difference in the prevalence for urban populations larger than 10 000 (47/10(5)) compared with smaller communities which were chiefly rural (34/10(5)).