The CDAI was developed in 1976 and is still the main outcome measure in Crohn’s disease drug trials. Response is usually defined as a fall of 70–100 points.
How to use the Crohn’s Disease Activity Index Calculator
- Sex
- Liquid or very soft stools – total over 7 days
- Abdominal pain – sum of daily ratings over 7 days (0 none – 3 severe)
- General wellbeing – sum of daily ratings over 7 days (0 well – 4 terrible)
- Number of complications (arthritis, iritis, skin lesions, fissure/fistula, fever > 37.8 °C)
- Taking antidiarrhoeal medicine
- Abdominal mass
- Haematocrit
- Weight
- Standard (ideal) weight
Results update as you type, and every field accepts the units shown in its menu.
How it works
Fill in a 7-day diary and enter the totals, plus the current examination and blood results.
Inputs explained
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Liquid or very soft stools – total over 7 days | A number |
| Abdominal pain – sum of daily ratings over 7 days (0 none – 3 severe) | A number |
| General wellbeing – sum of daily ratings over 7 days (0 well – 4 terrible) | A number |
| Number of complications (arthritis, iritis, skin lesions, fissure/fistula, fever > 37.8 °C) | A number |
| Taking antidiarrhoeal medicine | Choose one: No, Yes |
| Abdominal mass | Choose one: None, Questionable, Definite |
| Haematocrit | In % |
| Weight | Units: kg, lb, st, g |
| Standard (ideal) weight | Units: kg, lb, st, g |
Example values
How the main result changes when Liquid or very soft stools – total over 7 days changes and everything else stays at the example values above:
| Liquid or very soft stools – total over 7 days | CDAI |
|---|---|
| 10 | 206 |
| 15 | 216 |
| 20 | 226 |
| 25 | 236 |
| 30 | 246 |
| 40 | 266 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
CDAI = 2 × liquid stools (7-day total) + 5 × abdominal pain (7-day sum, 0–3/day) + 7 × general wellbeing (7-day sum, 0–4/day) + 20 × complications + 30 × antidiarrhoeal use + 10 × abdominal mass (0, 2 or 5) + 6 × (expected − actual haematocrit) + (1 − weight ÷ standard weight) × 100
< 150 remission · 150–220 mild · 220–450 moderate · > 450 severe
Worked example
Inputs — Sex: Male; Liquid or very soft stools – total over 7 days: 20; Abdominal pain – sum of daily ratings over 7 days (0 none – 3 severe): 7; General wellbeing – sum of daily ratings over 7 days (0 well – 4 terrible): 10; Number of complications (arthritis, iritis, skin lesions, fissure/fistula, fever > 37.8 °C): 1; Taking antidiarrhoeal medicine: No; Abdominal mass: None; Haematocrit: 38 %; Weight: 65 kg; Standard (ideal) weight: 70 kg.
Results — CDAI = 226; Disease activity = Moderate.
Key terms
- CDAI
- Crohn's Disease Activity Index.
Frequently asked questions
What CDAI means remission?
Below 150.
What is a clinical response?
A fall of at least 70 (or 100) points.
Why keep a diary?
Three of the eight items come from 7 days of symptom recording.