Q&A: CMI and surgical cases

Q: I’ve heard that when the volume of surgical cases is flat, any movement in the case mix index (CMI) represents an increased complexity of the patients. Can you explain what that means?

A: When a facility does the same amount of the same procedures on the same type of patient population their surgical CMI will remain the same or become “flat.” To increase your CMI or show movement in the CMI, the complexity of the patient population will need to increase or your facility would need to start preforming different types of surgical procedures that lead to a higher weighted DRG.

To calculate the case mix index, the final DRG assigned is multiplied by the number of patients discharged with that particular medical or surgical DRG, then multiplied by the relative weight of that DRG. To make a difference in the CMI, you would need to have more patients discharged with DRGs that have higher relative weights.

This can be accomplished by assigning secondary diagnoses that CMS identifies as either CCs or MCCs. These CC/MCCs represent an increase in the patient’s severity of illness or complexity. We always want to make sure that the documentation supports the most appropriate principal diagnosis along with any secondary diagnoses and procedures.

Editor’s note: Sharme Brodie, RN, CCDS, CDI education specialist for HCPro/ACDIS in Middleton, Massachusetts, answered this question. Contact her at sbrodie@hcpro.com. For more information on our CDI Boot Camps, click here.