CDAI calculator (Crohn's Disease Activity Index)

By Joanna Michałowska, PhD candidate
Last updated: Dec 02, 2020

The CDAI calculator (Crohn's Disease Activity Index calculator) determines the severity of symptoms in patients with Crohn's disease. We associate this condition with a variety of symptoms that affect the quality of life and health status of the patient. We therefore need to quantify these symptoms in order to to report the disease's remission, response to treatment, or to identify the patient's quality of life.

If you're interested in this kind of calculator, you might also want to check out our Charlson Comorbidity Index calculator that quickly estimates survival in patients with multiple comorbidities.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace professional medical advice. CDAI scores should be calculated individually by a qualified gastroenterologist.

What is Crohn's disease?

Crohn's disease is a lifelong inflammatory bowel disease. It can affect any segment of the gastrointestinal tract, from the mouth to the anus. The most frequent symptoms include:

  • abdominal pain;
  • diarrhea;
  • fever;
  • abdominal distension;
  • unintended weight loss;
  • iron deficiency (anemia);
  • skin rashes;
  • arthritis; and
  • tiredness.

Moreover, patients with Crohn's disease are at greater risk of colon cancer and small bowel cancer.

The causes of Crohn's disease are unknown. It is believed that a combination of environmental, immune, and bacterial factors in genetically susceptible individuals play a role in developing this condition.

What is Crohn's Disease Activity Index (CDAI)?

The Crohn's Disease Activity Index (CDAI) is a tool that determines the severity of symptoms in patients with Crohn's disease. [Experts from the Midwest Regional Health Center in Illinois developed it in 1976].(

Application of CDAI:

  • determination of current severity of Crohn's disease;
  • quantification of symptoms;
  • defining response to treatment;
  • remission assessment; and
  • evaluation of quality of life.

The index consists of eight determinants. Each of them has a weighting factor (expressed in brackets):

  • Number of liquid stools in the past 7 days [x2].
  • Severity of abdominal pain (scale from 0 to 3), [average in the past 7 days x5].
  • General well being (scale from 0 to 4, where 4 is 'terrible'), [average in the past 7 days x7].
  • Presence of additional complications [number of complications x20]:
    • arthritis or arthralgia;
    • inflammation of the iris or uveitis;
    • presence of skin disease: erythema nodosum, pyoderma gangrenosum, or aphthous ulcers;
    • anal fissures, fistulae or abscesses;
    • other fistulae; or
    • fever in the past 7 days (body temperature higher than 100°F/37.8°C).
  • Use of antidiarrheal medication in the past 7 days (yes - 1 point, no - 0 points), [x30].
  • Presence of an abdominal mass, where is 0 is 'none', 2 - 'questionable', 5 - 'definite' [x10].
  • Decreased hematocrit:

47% in men (42% in women) - current hematocrit [x6].

  • Deviation from standard weight:

(ideal - observed) / ideal * 100 [x1].

At the end we sum up the points to assess CDAI score.

How to interpret CDAI score?

We can interpret CDAI score as follows:

  • CDAI score < 150 - remission of Crohn's disease;
  • CDAI score between 150 and 450 - active disease;
  • CDAI score > 450 - severe disease; and
  • Decrease of CDAI score higher than by 70 points - response to treatment.

How to use CDAI calculator?

Follow the steps below to calculate the CDAI score for your patient using this CDAI calculator:

  1. Enter the patient's current weight.
  2. Enter the patient's ideal weight - if you don't know this value, use our ideal weight calculator.
  3. Choose the patient's sex.
  4. Enter number of liquid stools in the past 7 days.
  5. Define if your patient experienced abdominal pain in the last 7 days.
  6. Determine the general well-being of the patient in the past 7 days.
  7. State if the patient was using antidiarrheal drugs in the past 7 days.
  8. Define the presence of an abdominal mass.
  9. Enter the patient's current hematocrit.
  10. Choose relevant complications from the list.

That's all. We will display the CDAI score with an interpretation at the bottom of CDAI calculator.

Joanna Michałowska, PhD candidate
Current weight
Ideal weight
💡 You can calculate ideal weight using our ideal weight calculator.
Number of liquid stools
Abdominal pain
Overall well-being
Generally well
Antidiarrheal drugs
Abdominal mass
Current hematocrit
Arthritis or arthralgias
Iritis or uveitis
Skin disease
Anal fissure, fistula, or abscess
Other fistula
CDAI score
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