CDAI Basics and Moderate to Severe Crohn’s – Part 2

In part 2 of our series on CDAI basics in Crohn’s disease, I wanted to cover moderate to severe Crohn’s disease and how treatment may look a little different. As a quick refresher, CDAI stands for Crohn’s Disease Activity Index and as you can imagine it is a scoring system that provides an assessment of a patient’s Crohn’s symptoms. Here’s a quick summary from our previous post:

  • Clinical remission is defined as a score of <150. In general, these patients aren’t going to have any symptoms of their disease.
  • Mild Crohn’s disease is defined as a CDAI of 150-220. These patients tend to be upright, non-hospitalized patients with mild GI symptoms.
  • Moderate to severe Crohn’s disease is defined as a score of 220-450. They tend to have more symptoms and often have failed drug therapy for mild disease.
  • Severe-fulminant (CDAI >450); These patients have continued symptoms even with significant drug therapy like corticosteroids or biologics on board. Fever, significant vomiting and other GI symptoms, obstruction, substantial weight loss, and other systemic symptoms may be present.

Moderate to Severe Crohn’s – Remission

Let’s address moderate to severe patients looking for medications to help put them in clinical remission. In these patients, we will jump to using our biologic agents and most likely combine them with an immunomodulator (azathioprine, mercaptopurine, or methotrexate). Infliximab (Remicade and biosimilars) and adalimumab (Humira) are the biologic agents I have seen most commonly used in practice. As for the immunomodulator, I have seen all of the above used. One critical thing to remember prior to azathioprine or mercaptopurine use is to do thiopurine methyltransferase (TPMT) testing. In patients with TPMT deficiency, a significantly greater risk of myelosuppression exists. (This nugget is definitely something I’ve seen come up on exams throughout my career!) Steroids can also be used for initial symptom management of a Crohn’s flare but are not recommended long term. I discussed which steroid is most often used in Crohn’s disease in Part 1.


For patients in the moderate to severe category, once remission is obtained, the patient is generally going to continue on the same medications. There really isn’t a clear consensus as to when we can try to stop either of these medications, but if the patient is clinically stable and is far removed from their latest Crohn’s flare (1 year or more) it may be considered to try to start tapering/discontinuing the immunomodulator or biologic. As of the time of this blog post, here were the latest Crohn’s disease guidelines in full detail.

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Written By Eric Christianson

July 13, 2022

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