A simple classification of Crohn's disease: Report of the Working Party for the world congresses of gastroenterology, Vienna 1998

Crohn's disease is a heterogeneous entity. Previous attempts of classificat ion have been based primarily on anatomic location and behavior of disease. However, no uniform definition of patient subgroups has yet achieved broad acceptance. The aim of this international Working Party was to develop a s imple classification of Crohn's disease based on objective variables. Eight outcome-related variables relevant to Crohn's disease were identified and stepwise evaluated in 413 consecutive cases, a database survey, and by clin ical considerations. Allocation of variables was conducted with well-define d Crohn's disease populations from Europe and North America. Cross-table an alyses were performed by chi-square testing. Three variables were finally e lected: Age at Diagnosis [below 40 years (A1), equal to or above 40 years ( A2)], Location [terminal ileum (L1), colon (L2), ileocolon (L3), upper gast rointestinal (L4)], and Behavior [nonstricturing nonpenetrating (B1), stric turing (B1), penetrating (B3)]. The allocation of patients to these 24 subg roups proved feasible and resulted in specific disease cluster s. Cross-tab le analyses revealed associations between Age at Diagnosis and Location, an d between Behavior and Location (all p < 0.001). The Vienna classification of Crohn's disease provides distinct definitions to categorize Crohn's pati ents into 24 subgroups. Operational guidelines should be used for the chara cterization of patients in clinical trials as well as for correlation of pa rticular phenotypes with putative biologic markers or environmental factors .