Description of the problem or issue
Crohn’s disease (CD) is a chronic inflammatory disease of unknown aetiology that can affect any part of the gastrointestinal tract. Clinically the disease presents with diarrhea, abdominal pain, fatigue and weight loss and is characterized by chronicity and a relapsing-remitting course. Endoscopic findings include mucosal edema, erythema granularity, and friability and ulcers. Disease activity may be classified as mild, moderate, severe, or fulminant based on combined clinical and endoscopic assessments. Although CD may involve any part of the gastrointestinal tract, approximately 20% of patients have isolated colonic involvement, 30% have disease limited to the small bowel, and 50% of patients have involvement of both the ileum and the colon.
Several endoscopic and clinical indices have been developed to evaluate CD activity in clinical trials. It is now apparent that a poor correlation exits between symptoms as measured by an instrument such as the Crohn’s Disease Activity Index (CDAI) and endoscopic measures. Recently increased importance has been placed on the use of endoscopic instruments as outcome measures in clinical research since these are potentially more objective than symptom based indices. Therefore, the operating properties of these endoscopic indices must be clearly defined. In particular an endoscopic index must be valid – it must measure the outcome that it is intended to assess; responsive – it must detect a meaningful change in health status; and it must be reliable – meaning that consistent results are obtained in patients whose clinical status has remained stable (Kirshner 1985). Furthermore, an ideal instrument should be highly feasible to use in the setting of a clinical trial. Currently, the Crohn's Disease Endoscopic Index of Severity (CDEIS) (Mary 1989) and the Simple Endoscopic Score for Crohn's Disease (SES-CD) (Daperno 2004) are used to assess eligibility and response to therapy in clinical trials. However, it is notable that neither of these instruments have been fully validated.
The Crohn's Disease Endoscopic Index of Severity (CDEIS) assesses five segments of the intestine: rectum, sigmoid and left colon, traverse colon, right colon, and ileum (Mary 1989). The presence of deep and superficial ulceration, the percentage of ulcerated surface and the percentage of surface involved by CD are measured on a 10 centimetre visual analogue scale, for each colonic segment. Additionally, the presence of ulcerated stenosis and non-ulcerated stenoses are assessed. These items are weighted and summed to yield a total score that ranges from 0 to 44. Higher scores mean more severe disease.
The Simple Endoscopic Score for Crohn's Disease (SES-CD) evaluates four endoscopic items (ulcer size, proportion of the surface area that is ulcerated, proportion of the surface area affected, and stenosis). Each item is scored by segment on a scale from zero to three where higher scores indicate higher disease activity (Daperno 2004).
Why it is important to do this review
There are few data available on the operating properties of these two indices despite their widespread use as outcomes in clinical trials and systematic reviews. This review will evaluate the relative merits of the two indices and identify areas where further research is needed to develop an optimal evaluative instrument for use as an outcome in clinical trials and systematic reviews.