Interpretation
| Result | Meaning |
|---|---|
| < 150 | Remission |
| 150–219 | Mild |
| 220–450 | Moderate |
| > 450 | Severe |
| Fall ≥100 | Clinical response |
Formula
CDAI = 2 × liquid stools (7-day sum) + 5 × abdominal pain (7-day sum, 0–3/day) + 7 × well-being (7-day sum, 0–4/day) + 20 × number of complication categories + 30 × antidiarrheal use + 10 × abdominal mass (0/2/5) + 6 × (expected Hct − Hct; 47 men, 42 women) + 1 × % below standard weight [100 × (1 − weight/standard weight)]
Clinical pearls
- Convention used here (as in most trial protocols): the hematocrit term is floored at 0 and the weight term at −10. Best's 1976 paper did not specify floors.
- Standard weight comes from height-based tables; if unavailable, an ideal body weight formula (e.g. Devine) is a common substitute.
- Complication categories (20 each): arthritis/arthralgia; iritis/uveitis; erythema nodosum, pyoderma gangrenosum or aphthous stomatitis; anal fissure, fistula or abscess; other fistula; fever >37.8 °C in the past week.
Examples
cdai 7 day stools 28 pain sum 10 wellbeing sum 14 arthralgia no mass hct 38 male weight 65 ideal weight 72Crohn's disease activity index: 14 liquid stools over a week, pain sum 7, well-being sum 7, no complications, no antidiarrheals, no mass, female, hematocrit 40, weight 60 kg, standard weight 60 kgcdai stools 50 pain 18 wellbeing 21 fistula fever imodium definite mass hct 30 male wt 55 ibw 70
FAQ
What CDAI score is remission?
A CDAI below 150 defines clinical remission; above 450 is severe disease.
Why is CDAI hard to use in clinic?
It needs a 7-day symptom diary, hematocrit and standard weight; the Harvey-Bradshaw Index is a simpler bedside alternative.