Crohn's Disease Activity Index
The Crohn's Disease Activity Index or CDAI is a research tool used to quantify the symptoms of patients with Crohn's disease. This is of importance in research studies done on medications used to treat Crohn's disease; most major studies on newer medications use the CDAI in order to define response or remission of disease. As Crohn's disease is a disease with a variety of symptoms that affect quality of life, the quantification of symptoms may be of secondary importance to a quantitative assessment of the effect on quality of life. This has been addressed by the Inflammatory Bowel Disease Questionnaire (IBDQ) and other indices of quality of life for patients with Crohn's disease.
Components of the index
The CDAI was developed by WR Best and colleagues from the Midwest Regional Health Center in Illinois, in 1976. The index consists of eight factors, each summed after adjustment with a weighting factor. The components of the CDAI and weighting factors are the following:
|Clinical or laboratory variable||Weighting factor|
|Number of liquid or soft stools each day for seven days||x 2|
|Abdominal pain (graded from 0-3 on severity) each day for seven days||x 5|
|General well being, subjectively assessed from 0 (well) to 4 (terrible) each day for seven days||x 7|
|Presence of complications*||x 20|
|Taking Lomitil or opiates for diarrhea||x 30|
|Presence of an abdominal mass (0 as none, 2 as questionable, 5 as definite)||x 10|
|Hematocrit of <0.47 in men and <0.42 in women||x 6|
|Percentage deviation from standard weight||x 1|
*One point each is added for each set of complications:
- the presence of joint pains (arthralgia) or frank arthritis
- inflammation of the iris or uveitis
- presence of erythema nodosum, pyoderma gangrenosum, or aphthous ulcers
- anal fissures, fistulae or abscesses
- other fistulae
- fever during the previous week.
Remission of Crohn's disease is defined as a fall in the CDAI of less than 150. Severe disease was defined as a value of greater than 450. Most major research studies on medications in Crohn's disease define response as a fall of the CDAI of greater than 70 points.
The Harvey-Bradshaw index was devised in 1980 as a simpler version of the CDAI for data collection purposes. It consists of only clinical parameters:
- general well-being (0 = very well, 1 = slightly below average, 2 = poor, 3 = very poor, 4 = terrible)
- abdominal pain (0 = none, 1 = mild, 2 = moderate, 3 = severe)
- number of liquid stools per day
- abdominal mass (0 = none, 1 = dubious, 2 = definite, 3 = tender)
- complications, as above, with one point for each.
A Simple Index of Crohn's disease activity has also been developed.
Validation of the CDAI
While the CDAI is considered to be the gold standard for assessing disease activity in Crohn's disease, validation of the index has been varied. A key criticism of the CDAI is that it does not incorporate a subjective assessment of quality of life, endoscopic factors, or systemic features, such as fatigue into its calculation. Interestingly, the CDAI correlated well with protein loss in the bowel in patients with protein losing enteropathy.
Inflammatory Bowel Disease Questionnaire
As most symptoms of Crohn's disease broadly affect quality of life, attempts have been made to incorporate physical, social, and emotional performance characteristics into tests for severity of Crohn's disease. The Inflammatory Bowel Disease Questionnaire (IBDQ) was developed to incorporate elements of social, systemic and emotional symptoms, as well as bowel related symptoms into an activity index. In a study of 305 patients in Ontario, the IBDQ was found to correlate well with the CDAI in assessing disease activity, but had the added benefit of being a more robust tool for determining the effect of symptoms on perceived quality of life.
- Irvine E, Feagan B, Rochon J, Archambault A, Fedorak R, Groll A, Kinnear D, Saibil F, McDonald J (1994). "Quality of life: a valid and reliable measure of therapeutic efficacy in the treatment of inflammatory bowel disease. Canadian Crohn's Relapse Prevention Trial Study Group.". Gastroenterology. 106 (2): 287–96. PMID 8299896.
- Best WR, Becktel JM, Singleton JW, Kern F Jr. (1976). "Development of a Crohn's disease activity index. National Cooperative Crohn's Disease Study". Gastroenterology. 70 (3): 439–444. PMID 1248701.
- Sands B, Anderson F, Bernstein C, Chey W, Feagan B, Fedorak R, Kamm M, Korzenik J, Lashner B, Onken J, Rachmilewitz D, Rutgeerts P, Wild G, Wolf D, Marsters P, Travers S, Blank M, van Deventer S (2004). "Infliximab maintenance therapy for fistulizing Crohn's disease.". N Engl J Med. 350 (9): 876–85. PMID 14985485.
- Hanauer S, Feagan B, Lichtenstein G, Mayer L, Schreiber S, Colombel J, Rachmilewitz D, Wolf D, Olson A, Bao W, Rutgeerts P (2002). "Maintenance infliximab for Crohn's disease: the ACCENT I randomised trial.". Lancet. 359 (9317): 1541–9. PMID 12047962.
- Harvey R, Bradshaw J (1980). "A simple index of Crohn's-disease activity.". Lancet. 1 (8167): 514. PMID 6102236.
- Elliott P, Lennard-Jones J, Hathway N (1980). "Simple index of Crohn's disease activity.". Lancet. 1 (8173): 876. PMID 6103229.
- Jørgensen L, Fredholm L, Hyltoft Petersen P, Hey H, Munkholm P, Brandslund I (2005). "How accurate are clinical activity indices for scoring of disease activity in inflammatory bowel disease (IBD)?". Clin Chem Lab Med. 43 (4): 403–11. PMID 15899657.
- Yoshida E. "The Crohn's Disease Activity Index, its derivatives and the Inflammatory Bowel Disease Questionnaire: a review of instruments to assess Crohn's disease.". Can J Gastroenterol. 13 (1): 65–73. PMID 10099817.
- Acciuffi S, Ghosh S, Ferguson A (1996). "Strengths and limitations of the Crohn's disease activity index, revealed by an objective gut lavage test of gastrointestinal protein loss.". Aliment Pharmacol Ther. 10 (3): 321–6. PMID 8791958.