How to Calculate Case Mix Index

Case mix index (CMI) indicates the average weights of a healthcare facility's diagnosis-related groups (DRG). The higher a facility's CMI, the greater the number of high cost services the facility performs. The more high cost services performed, the more money per patient the facility receives.

Things You'll Need

• DRGs
• DRG relative weights
• Calculator

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Instructions

• 1

  Select a time period to calculate the CMI, such as a week, a month or a year. As an example, calculate a hospital's CMI for a month.

• 2

  Determine the total number of DRGs billed within the time period specified in Step 1. This figure can be obtained from your healthcare facility's financial department. As an example, there were 20 DRGs billed within the one month period.

• 3

  Add up all of the relative weights of the DRGs billed within the time period specified in Step 1. The relative weights are determined by Centers for Medicare & Medicaid Services (CMS). (See Resources for the most up-to-date relative weights.) As an example, the total relative weights for one month is 25.

• 4

  Divide the result from Step 2 by the result from Step 3 to calculate the CMI. In the example, dividing 20 by 25 equals 0.8. The hospital's CMI for a one month period is 0.8.