An investigation into the validity of the present classification of inflammatory bowel disease.

To assess the validity of the present subdivision of patients with inflammatory bowel disease into those with Crohn's disease of the small bowel or of the colon and those with ulcerative colitis, 252 patients with inflammatory bowel disease have been studied by questionnaire and case note review. One hundred and seventy-two variables concerning the nature and frequency of symptoms in remission and relapse, the incidence of complications and results of investigation have been analysed by computer. As expected, there were many highly significant variables between patients with ulcerative colitis and those with Crohn's disease of the small bowel. The latter showed evidence of a more severe disease course with more complications. There were similar, although less marked, differences between patients with Crohn's disease of the colon and those with Crohn's disease of the small bowel. There were very few differences in disease course between patients with Crohn's disease of the colon and those with ulcerative colitis. The results suggest that while separate classification of patients with Crohn's disease of the small bowel is justified on clinical grounds, the present separation of patients with disease confined to the colon into groups labelled ulcerative colitis or Crohn's disease of the colon is not. Alternative methods of classification should therefore be investigated.