Evaluation of diagnostic criteria for Crohn's disease in Japan

Background In Japan, Crohn's disease (CD) is diagnosed according to a single, well-established set of diagnostic criteria. However, no nationwide attempt has been made to determine which specific criteria within these diagnostic criteria are used to make diagnoses. Methods A questionnaire-based survey was conducted of patients given a definitive or suspected diagnosis of CD before January 2011 according to the Japanese Diagnostic Criteria for Crohn's Disease. The survey included 579 patients with a definitive diagnosis of CD and 59 patients with a suspected diagnosis of CD at 34 Japanese medical institutions. Results A total of 87.4 % of definitive diagnoses of CD were based on the criterion in the definite category: major finding A longitudinal ulcer (LU) or B cobblestone-like appearance (CSA). A total of 30.4% of definitive diagnoses were based on the criterion: major finding C non-caseating epithelioid cell granuloma (NCEG) with minor finding a irregular-shaped and/or quasi-circular ulcers or aphthous ulcerations found extensively in the gastrointestinal tract or b characteristic perianal lesions. Finally, 7.1 % of definitive diagnoses were made according to the criterion: all minor findings a, b and c characteristic gastric and/or duodenal lesions. Among suspected diagnoses of CD, 74.6 % were based on the criterion in the suspected category: one or two minor findings. Conclusions The Japanese diagnostic criteria for Crohn's disease consist of combinations of specific morphological findings. Many of the diagnoses were based on the findings of LU or CSA.