While building a test patient to evaluate against the DEN EXCEP portion of the logic, I noticed that when I add the Medication, Active: Systemic Corticosteroid/Prednisone Therapy data element, if a prednisone RxNorm code is populated within the data element (e.g., 1303125 - Prednisone 1 mg delayed release oral tablet) the patient evaluates as positive for the Medication, Active: Systemic Immunosuppressive Therapy data element in the DEN EXCL. If a non-prednisone code is populated in the data element, it evaluates as expected.

I did not evaluate the full extent of crosswalk between these two value sets. Most likely, there are several other RxNorm codes that cause the same problem.