[Epidemiology of chronic inflammatory bowel disease in Gijón, Asturias]

To determine several aspects of the epidemiology of chronic inflammatory bowel disease (IBD), including distribution of the various forms of IBD, sex, age at diagnosis considering lag-time to diagnosis, criteria used in the diagnosis, the relationship between educational level and activity, familial aggregation, phenotype (site and clinical type), number of admissions and mean hospital stay/year, surgical requirements and mortality.

We carried out a retrospective (1954-1993) and prospective (1994-97) descriptive epidemiologic population study, in the fifth health district of Gijón in Asturias (Spain), with 225,798 inhabitants. A total of 595 patients diagnosed with chronic IBD according to the diagnostic criteria described by Lennard-Jones and Truelove for Crohn's disease (CD) and ulcerative colitis (UC) and according to Ashley B. Price's criteria for indeterminate colitis (IC) were studied. In all patients a complete clinical follow-up was performed.

During the study period, we diagnosed 595 patients with IBD [305 patients with UC (51.3%), 272 (45.7%) patients with CD and 18 (3%) with IC]. Sex distribution was 287 females (48.2%) and 308 males (51.8%), with a male/female ratio of 1.07. Mean age at presentation was 38.79 +/- 17.44 years (UC: 43.37 +/- 17.55; CD: 33.98 +/- 16.16; IC: 33.73 +/- 13.48), p = 0.000. Age at onset prior to diagnosis was as follows: UC: 42.03; CD: 30.47; IC: 30.99 (p = 0.000). Diagnostic criteria used in UC was symptomatic in 99.01% (p = ns), endoscopic in 95.04% (p = 0.000), and pathologic in 87.21% (p = 0.000); in CD diagnostic criteria used was radiologic in 85.29% (p = 0.000). A total of 29.1% of patients with UC and 66.7% of those with CD had higher education (p = 0.0005). Family history was found in 9.8%. Anatomical site was as follows: in UC: rectum 21%, 28.2% rectum and sigmoid, 22.3% left colitis, 4.2% distal to hepatic flexure and 24% pancolitis; in CD: 32.72% terminal ileum, 19.11% colon, 37.13% ileo-colon, 11.02% extensive intestinal and 3.67% gastro-duodenal. A total of 8.37% of patients with UC and 14.51% of those with CD had been hospitalized during the previous 4 years; mean hospital stay was 1.63 days in UC and 2.27 days in CD. The mean surgical requirements were 0.54 +/- 1.08 (31.59%); UC: 0.11 +/- 0.36 (10.2%); CD: 1.04 +/- 1.38 (56.25%), p = 0.000. The mortality rate was 48.73 deaths/1,000 inhabitants (UC: T = 65.57; CD: T = 33.08; IC:T= 0) p = ns. The standardized mortality ratio was 4.83 (UC: 6.51; CD: 3.28).

We highlight the uniformity of the distribution of IBD in relation to types of disease and sex. Patients with CD had a higher level of education. Genetic components play an important role in these diseases and familial aggregation was high, especially in CD. Complicated situations are infrequent in this group of patients. Morbidity was higher in patients with CD as reflected by surgical requirements and hospital stay. Mortality was lower in CD than in UC.