Surveillance in ulcerative colitis: burdens and benefit.

A review of all patients with ulcerative colitis in one health district between 1975-84 revealed an incidence and prevalence of 7.1 and 84/100,000 population respectively. One hundred and ninety five new patients were diagnosed and 313 patients seen and followed up in the clinic for 1168 patient years. None of these patients died from colitis or a complication. On routine colonoscopy three cases had high grade dysplasia and two asymptomatic carcinomas (Duke's stage A and B). Eighty four patients were known to have ulcerative colitis, but were lost to follow up from the hospital clinic; the total time they were not under hospital surveillance was 315 patient years. At the end of the study these patients were contacted or clinical details obtained from their general practitioners. Five of these patients subsequently presented with symptomatic carcinomas (two Duke's B, one Duke's C and two with metastases); three of these five patients have died from their tumours. Of 48 patients thought to have only mild colitis on initial investigation 21 (43%) had substantial colitis (and two carcinomas) on colonoscopy after eight years of disease. Therefore, patients with apparently distal colitis should be followed in the clinic as well as those with known extensive colitis. For a surveillance programme in a district general hospital, eight patients per 100,000 population need to be seen weekly, 12 colonoscopies/100,000 population need to be carried out annually and the cost for each carcinoma detected is approximately 6015 pounds.