Introduction To assess IBD activity, many severity scales have been developed. Yet, most of them were not properly validated and did not go through robust methodology. Using different scoring systems makes it difficult to compare different trials especially when the end points are different. Because new therapies for IBD are rapidly emerging, there is a need to optimise and standardise methodology for assessing of disease activity in clinical trials. With the nationwide initiative to establish an IBD registry, a valid and easy to use activity measurement tool is needed. We believe that having a single disease activity index that is suitable for all types and presentations of IBD will make it very useful to monitor patients and assess their response to treatment.

Methods Literature search was conducted using MEDLINE and Google scholar database from January 1947 to 2011 to identify the clinical severity indeces commonly used in clinical trails. Seventeen indeces were identified for both Ulcerative coltis and Crohn's disease. We followed a clini-metric approach to develop the simple IBD clinical severity index. Common items between Ulcerative coltis and Crohn's disease were chosen. Few items were added to cover disease specific domains. The new index was examined by gastroenterologists and methodologists in Swansea University to ensure good face and content validity. The index was tested on 50 patients with different presentations of inflammatory bowel disease. Harvey Bradshaw index and Simple clinical colitis index were used for construct validity. Responsivness was checked by repeating the test within 2-week period.

Results The new index, simple IBD clinical severity index, showed good face and content validity. It covers all presentations of IBD including Crohn's disease, ulcerative coltis and perianal disease. It has good reliability and construct validity. It is easy to use in daily practice.

Conclusion Simple IBD clinical severity index is a new tool to assess the clinical activity of IBD. It is valid, reliable, user friendly and non-invasive index. Further studies are required to check how it performs on a wider range of patients.

Competing interests None declared.