The Crohn’s Disease Activity Index (CDAI) is just what it sounds like. It is an assessment tool designed to determine the severity of Crohn’s disease. Wait, isn’t this a diagnostic tool intended for diagnosticians? As a pharmacist, why do I need to know about it? The CDAI helps us determine the severity of Crohn’s disease which ultimately guides drug therapy for Crohn’s disease. In this post, I’d like to cover CDAI basics for pharmacists because you never know when it might show up in practice or on one of your board certification exams
As I like to do, let’s get right to the important stuff. The scoring is critical to guiding drug therapy.
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.
Assessing risk is also going to be important. A gastroenterologist will typically perform a risk assessment and categorize patients as low, moderate, or high risk. Endoscopy, labs, and determination of upper GI involvement are important in this stratification. Patients in the moderate to higher risk category will tend to get more aggressive treatment.
If you are still following along, you’ll care about how patient risk and CDAI basics for pharmacists relate to drug selection. Let’s give you an overview of associated treatments based on the severity of the disease.
In patients where remission is desired who have mild disease (CDAI <220) and are at lower risk, corticosteroids are going to be the initial go-to agent in most situations with preference given to budesonide. Four to eight weeks is generally the target length of use with a tapering plan to follow and patients ideally to be off the drug in 12 weeks total. Prednisone may also be considered. Recall that budesonide has a high first-pass metabolism which may help reduce systemic exposure. We ideally are looking to avoid long-term corticosteroids so these are generally avoided for chronic use. Mesalamine is also a consideration in those who may be leery about starting steroids but it should be noted that the evidence of benefit in Crohn’s disease is a bit more sketchy. In low-risk, mild severity patients who need maintenance therapy, mesalamine represents a more acceptable option. Sulfasalazine is a consideration as well, but the best evidence for its use is only demonstrated in patients with colitis.
In part 2 of Crohn’s disease, I will cover the use of biologics and other agents in moderate to severe disease.