Intra‐ and interobserver variation in the use of the vienna classification of Crohn's disease

Background: Crohn's disease is a heterogeneous disease, and several classification systems have been developed to classify the patients in more homogeneous groups. Our aim was to assess the intra‐ and interobserver variation when classifying patients according to the widely used Vifenna classification. Methods: Ten randomly selected Crohn's disease cases were presented to 11 Danish gastroenterologists with a special interest in inflammatory bowel diseases. Clinical details, together with endoscopic, radiologic, and pathologic reports, were presented to the participants as a PowerPoint slide show, sent by e‐mail with a data collection form. The experts were asked to classify the cases according to the Vienna classification and to evaluate intraobserver variation; the participants classified the patients 3 times. The strength of agreement was calculated using κ statistics. Results: Classification of the patients according to age gave a κ value of 1.00. The intraobserver κ value was good, with an average κ value of 0.75 (range, 0.42‐0.86) for location and 0.77 (range, 0.53‐1.00) for behavior. The mean overall interobserver κ value was 0.64 (range, 0.12‐1.00), which improved slightly between the first and third rounds. When classifying according to location and behavior, most patients were classified in 2 or 3 different ways, and in no patients was there full agreement among the observers for both location and behavior. Conclusions: In this study, we found an overall good interobserver agreement when using the Vienna classification, although when looking at individual cases, there was some disagreement.