CLINICAL COURSE DURING THE 1ST YEAR AFTER DIAGNOSIS IN ULCERATIVE-COLITIS AND CROHNS-DISEASE - RESULTS OF A LARGE, PROSPECTIVE POPULATION-BASED STUDY IN SOUTHEASTERN NORWAY, 1990-93

Background: The clinical course and prognosis in ulcerative colitis (U C) and Crohn's disease (CD) have been described in many studies, mostl y retrospective. Such studies are hampered by problems such as inclusi on over a long time period, proper definitions, incomplete case record s, and outdated methods of diagnosis. In a prospective study we identi fied 846 patients with inflammatory bowel disease (IBD) over a 4-year period from 1990 to 1993. Uniform diagnostic and therapeutic strategie s were used as a basis for later assessment of the short-term clinical course in different subgroups of UC and CD and analysis of potential risk factors for relapse or surgery. Methods: At the time of follow-up , a mean of 16.2 months after diagnosis, 496 UC patients and 232 CD pa tients, altogether 98%, were available for evaluation. A colonoscopy w as performed in 88% (410 of 465) of the UC patients attending a clinic al examination and in 76% (164 of 216) of the CD patients. Results: El even patients with UC and five patients with CD died during follow-up, four of complications related to IBD. The cumulative 1-year relapse r ate in the remaining patients was 50% for UC and 47% for CD. Of the pa tients with relapses 11% of the UC patients and 10% of the CD patients had a chronic relapsing course without any difference with regard to the various disease categories in UC or CD. An increased risk of relap se was found in patients less than 50 years old only in UC. In UC a hi gher risk for surgery was found in patients with extensive colitis com pared with left-sided colitis (P=0.011), and CD patients with small-bo wer involvement had a higher risk of surgery than patients with diseas e confined to the colon (P=0.021). There was no excess risk of relapse or surgery in smokers as compared with non-smokers or former smokers, nor did the risk of relapse vary with the level of cigarette consumpt ion in either UC or CD patients. Conclusion: The high relapse rate of around 50% for both UC and CD calls for a review of the existing treat ment. Further follow-up will be necessary to improve our ability to ma ke clinical decisions relating to medical and surgical treatment optio ns.