Introduction Due to the different presentations of patients with inflammatory bowel disease, several clinical severity indices were used in the past. Interestingly, most (if not all) of these indices were not properly validated and did not go through a robust methodology. Our aim is to develop a new clinical disease severity index that valid, easy obtainable in the clinic and suitable to all IBD patients.
Methods The development of Swansea IBD clinical severity index (SICSI) followed a clinimetric approach. Items were devised using IBD experts opinions and through reviewing 17 clinical severity indices commonly used in studies for UC and CD. To ensure items are applicable, we asked a small focus group of IBD specialists, statisticians and methodologists to review these items and ensure good face and content validity. Psychometric properties were tested on 210 patients to remove redundant items and shorten the index. Construct validity was checked using biochemical markers like CRP, WBC, HB and albumin and clinical indices which are: Harvey Bradshaw index, simple clinical colitis activity index and perianal disease activity index. If patient is having an endoscopy, endoscopic indices will be recorded as well which are mayo clinic score, Rachmilewitz scores and simple endoscopic score.
Results We found that 7 items account for 98% of the variance of the total score and they are: Abdominal pain or discomfort, stool consistency compared to the usual, blood in stool, number of stool frequency, general well being, nocturnal symptoms and urgency. Items that had high item total correlation > 0.8 like physician global assessment were removed from the index as they are redundant. Temperature and abdominal mass had a zero variance score and did not add any value to the total score and were removed during factor analysis. Internal consistency (Correlation of items with each other) was acceptable (Cronbach alpha = 0.827). SICSI had good correlation with the clinical, biochemical and endoscopic severity scores (r > 0.5).
Conclusion It is clear that the Swansea IBD clinical severity index will perform well in clinical practise. Further studies are going on to implement the index in clincal practise. The index has been incorporated into our local IBD registry to follow up and moniter patients. There are plans to develop an iPhone application.
Disclosure of Interest None Declared
Marx RG, C Bombardier C, Hogg-Johnson S, Wright JG. Clinimetric and psychometric strategies for development of a health measurement scale. J Clin Epidemiol, 1999. 52(2): p. 105–11.
Streiner DL, Norman GR. Health measurement scales. A practical guided to their development uses. 4th ed, 2008 OUP.