An epidemiological study of inflammatory bowel disease : (incidence, mortality, short-term and long-term prognosis in three centres in England during the years 1977-93).
Both ulcerative colitis and Crohn's disease are chronic disorders of unknown aetiology.
The purpose of this study was to map the incidence and current natural history of both
diseases so that this knowledge might assist in the better management of patients. The
study is of a cohort of 723 patients with inflammatory bowel disease diagnosed in
Wolverhampton, Salisbury and Swindon between 1977-86 and followed up prospectively
until 31st December 1993. The incidence, mortality, survival and short-term prognosis in
relation to age, sex, length of history, severity and extent of disease were analysed. The
long-term prognosis was examined in relation to the course, relapses, recurrence, surgical
treatment, remote complications and cancer risk.
No increase in the incidence of ulcerative colitis and Crohn's disease was found. The
age distribution of both diseases showed a bimodal pattern with peaks at 20-39 and 50-69.
The incidence of ulcerative colitis was highest in Wolverhampton as was the incidence of
Crohn's disease in Swindon. It was similar between men and women.
The Standardised Mortality Ratio (~MR) of ulcerative colitis and Crohn's disease was
similar to the general population, except that it was significantly higher in Swindon. The
excess death was not from ulcerative colitis.
Ulcerative colitis: Rank correlation analysis showed length of history, extent and
severity of disease were strongly associated with prognosis of first attack. There was also
a strong inter-relationship between these factors.
80% of patients were in remission at any time but at 15 years 72% had experienced at
least one relapse and 15% of patients had undergone colectomy. The severity and extent
of disease at first attack was found to be predictive of colectomy.
The prognosis was different in Wolverhampton. More patients underwent surgery and
colectomy. When the influence of race was considered South Asian patients presented
with more severe and extensive colitis and they were younger than white patients. The
relapse and colectomy rate were greater in South Asians during follow up. The racial
differences in incidence, course and prognosis of ulcerative colitis needs further
The lower incidence in Swindon, less common extensive colitis both at presentation
and during follow up, and lower colectomy rate might suggest a milder form of ulcerative
Crohn's disease: Rank correlation analysis showed age, site of disease and length
of history were not associated with short term prognosis.
Almost 80% of patients were in remission at any time and 84% experienced at least
one relapse in 14 years which required treatment. The relapse rate in Swindon was higher
but were mostly treated medically.47% of patients had undergone some form of intestinal resection in 14 years, 33%
required a second operation within 10 years. This study failed to show any relationship
between the first recurrence and age at diagnosis, length of history or initial site of
The prognosis was different in Wolverhampton; more patients underwent intestinal
resection. In Wolverhampton there were significantly more patients with anal Crohn's and
38% of these patients who underwent surgery did so because of anal Crohn's.
There was a improvement in the prognosis of VC and CD in the present study in
comparison to the studies in the last few decades. The apparent improvement of outcome
may result from changing criteria and speed of diagnosis, the introduction of new
treatments and their rapid application. The need exists for new and improved treatment
for those patients who do not currently respond adequately. Outcome measurements
suggest that most, but not all patients, with ulcerative colitis and Crohn's disease lead a
relatively normal social and working life. The results may be of value for reassessing the
life insurance risk of patients with inflammatory bowel disease. The results suggest there
is a need for further reallocation of resources for both research and health care delivery to