The CDAI allows doctors to assess the severity of your Crohn’s disease and the progress of your treatment. It considers clinical findings and self-observation of your symptoms over a week.

Crohn’s disease is a form of inflammatory bowel disease (IBD) that can develop in any part of your digestive tract. When diagnosing Crohn’s disease, a doctor will rely on a combination of tests, including a physical exam, blood work, and imaging tests.

Another important part of Crohn’s disease diagnosis and long-term management is regularly assessing the severity of your condition. Doctors can determine the severity of your Crohn’s disease based on your symptoms and any complications.

They may also consider the Crohn’s Disease Activity Index (CDAI). First developed in 1976 by researchers with the National Cooperative Crohn’s Disease Study Group, the CDAI can provide doctors with insights into how well your treatment plan may (or may not) be working.

Keep reading to learn more about the CDAI, including how the scores are calculated, what the results might mean, and which other scoring systems doctors may use.

If a doctor orders a CDAI to assess the severity of your Crohn’s, they will ask you a series of questions.

These questions are related to the frequency and severity of symptoms you experience over a 7-day period, such as:

  • diarrhea
  • blood in your stool (which may indicate ulcers)
  • abdominal pain
  • joint pain
  • skin or mouth lesions
  • eye inflammation
  • nausea or vomiting
  • abdominal tenderness
  • sleep disturbances related to symptoms

The questions may also consider certain complications, such as fistulas. Other questions involve your body weight, appetite, and overall well-being. Your overall score will also consider your hematocrit levels based on recent blood tests.

You’ll receive a score for each of your answers, and your doctor will add up those scores to reveal your CDAI score.

CDAI scores have a range of 0–600.

The higher your score, the more severe your Crohn’s may be. A lower score indicates less severe disease. Experts suggest the following interpretations for these score ranges:

  • 0–149: Your Crohn’s may be in remission.
  • 150–220: Crohn’s disease is active but mild.
  • 220–450: These scores may indicate moderate to severe Crohn’s.
  • 451–600: These scores indicate more severe Crohn’s disease.

How accurate are CDAI scores?

CDAI scores are based on a combination of your symptoms, any signs a doctor detects during a physical exam, and blood test results. Keeping an accurate diary of your symptoms over 7 days is critical.

CDAI scores can help a doctor quickly determine the severity of your Crohn’s disease, but they may need to use additional tests, such as imaging or endoscopy, to confirm these results.

There are possible limitations to CDAI scoring. For example, one 2021 study noted discrepancies in self-reporting of certain symptoms, such as the number of soft or bloody stools people experienced in a given week.

Was this helpful?

Doctors use CDAI scores to help determine how severe your Crohn’s disease currently is and whether your current treatment plan is working. A 100-point or greater reduction in your CDAI score from previous assessments may be just one sign that you’re responding to treatment.

Your CDAI score can also help a doctor decide whether you need imaging tests, such as an intestinal endoscopy or a computed tomography (CT) scan of your digestive tract.

Since its introduction in the 1970s, the CDAI has inspired the creation of other assessment tools for Crohn’s. Clinicians or researchers may use the following scoring systems.

Harvey-Bradshaw Index

The Harvey-Bradshaw Index (HBI) is another assessment tool doctors use to determine the severity of Crohn’s disease. It’s a simplified version of the CDAI, though a doctor may use both assessments.

The HBI consists of five questions, and you receive a score based on your answers. Scores range from 0 to more than 16. The higher the score, the more severe your Crohn’s may be.

PCDAI score

The CDAI is a tool used for adults with Crohn’s disease. For children, doctors may use the Pediatric Crohn’s Disease Activity Index (PCDAI) instead. PCDAI scores focus on stool patterns, abdominal pain, weight, height, and extraintestinal signs of Crohn’s, such as rashes.

Simple Endoscopic Score

A Simple Endoscopic Score for Crohn’s Disease (SES-CD) uses results from an endoscopy to capture images of your digestive tract. The images help doctors determine the extent of disease in both your small and large intestines. The SES-CD also notes whether ulcers are present and how large they are.

Doctors consider the SES-CD an emergency scoring system for Crohn’s and use it primarily in clinical trials.

Is there an ulcerative colitis disease activity index?

Similar tools exist to help doctors assess the severity of ulcerative colitis (UC), another type of IBD.

One common tool is the Partial Mayo Scoring Index. It’s similar to the HBI in that it uses a score based on five questions related to symptoms and complications. Scores range from 0–9, with higher scores indicating severe UC.

Was this helpful?

Doctors have used the CDAI since the mid-1970s to help assess Crohn’s disease severity and treatment responses. It provides a score based on your symptoms, complications, and clinical data.

Because Crohn’s disease is a complicated chronic condition, the importance of data from both a doctor and a diary of your symptoms can’t be understated. For these reasons, researchers are working to improve the current CDAI system to make it more accessible and accurate.