In CDI metrics, what best describes the difference between case mix and CMI?

• A. Case mix is the average DRG weight; CMI is the distribution of cases by DRG or severity.
• B. Case mix is the distribution of cases by DRG or severity; CMI is the average DRG weight the hospital collects.
• C. Case mix and CMI are unrelated metrics used in separate systems.
• D. Case mix refers to payer mix; CMI refers to clinical documentation completeness.

Answer: (B)

In CDI metrics, you’re looking at two related ideas about the patient population. Case mix describes the distribution of cases across DRGs or severity levels—that is, how often each DRG or level occurs in the patient sample. The Case Mix Index is a single summary number that comes from that mix: the average DRG weight per discharge. It’s calculated by summing the DRG weights for all discharges and dividing by the number of discharges, so it reflects overall resource intensity. A higher CMI means the hospital’s patients, on average, require more resource use or are more complex.

This makes the best choice: case mix is the distribution of cases by DRG or severity; CMI is the average DRG weight the hospital collects. The other statements mix up these definitions or bring in unrelated concepts like payer mix or documentation completeness.