Increasing incidence of both juvenile-onset Crohn's disease and ulcerative colitis in Scotland.

OBJECTIVE: A previous study reported a three-fold rise in the incidence of juvenile-onset Crohn's disease in Scottish children and a marginal fall in ulcerative colitis between 1968 and 1983. The present study aimed to document the incidence of juvenile-onset inflammatory bowel disease between 1981 and 1995 and examine temporal trends between 1968 and 1995 in Scotland.

SETTING: Scotland (latitude 55-60 degrees N) has a total area of 77 837 km2 (30 405 square miles) and includes four urban centres each with a population of over 100,000.

PARTICIPANTS: The Scottish hospital discharges linked database was used to identify 1002 patients less than 19 years old who were coded as having inflammatory bowel disease between 1981 and 1997. All case notes were reviewed and diagnoses verified. Incident cases were defined as those with symptom onset before or at 16 years of age between 1 January 1981 and 31 December 1995.

RESULTS: During the 15 year period 1981-1995, 438 incident cases of Crohn's disease and 227 of ulcerative colitis were identified, giving standardized incidences of 2.5 cases and 1.3 cases per 100,000 population per year for Crohn's disease and ulcerative colitis respectively. On 31 December 1995 there were 150 children < or = 16 years of age with Crohn's disease and 101 with ulcerative colitis, giving crude prevalences of 13.7 cases per 100,000 population for Crohn's disease and 9.2 for ulcerative colitis. The continuing rise in Crohn's disease incidence between 1981 and 1995 fits that predicted by linear trend analysis of the 1968-1983 data. The incidence of Crohn's disease in the 12-16 age range almost doubled between 1981 and 1995 and was greater for males than females. Ulcerative colitis incidence was thought to show a slight fall in the 1968-1983 data, but this is reversed in the 1981-1995 data.

CONCLUSION: The incidence of juvenile-onset Crohn's disease continues to rise in Scotland and the prevalence has increased by 30% since 1983. Unlike the previous report from Scotland, the incidence of juvenile-onset ulcerative colitis also is apparently rising. Whether this represents a real rise in incidence, or merely the inclusion of milder cases which were not previously hospitalized remains uncertain.