Content Link: MS-DRGs and CMI
The case mix of a patient population is a description of that population based on any number of the following characteristics such as age, gender, treatments received or resources used. Case Mix Analysis is used to determine reimbursement, to describe a population being served and to identify differences in practice patterns or coding complexity.
The case mix index is the average of the relative weights of all cases treated at a given facility. The theoretical average CMI is 1.000. CMI’s over 1.000 signify more complex cases and CMI’s less than 1.000 signify less complex cases. Factors that influence a facility’s case mix index include:
Case Mix Analysis begins with the calculation of the Case Mix Index. The Case-Mix Index is the average of the relative weights of all cases treated at a given facility or by a given physician. The formula for calculating the Case Mix Index is:
The total number of CMS Relative Weights for all of the cases divided by the total number of patients served.
Example: Commonwealth Hospital – Top 5 MS DRGs
The total CMS Relative Weight is 213.0332
The total number of patients served is 78
The Case Mix Index is 213.0332 / 78 = 2.7311
Part I Written Assignment
You are the HIM Director for PrimeCare Medical Center and you are charged with the task of analyzing your facility’s case mix and comparing your Case Mix Index with comparable facilities in your area. The top 5 procedures performed in your facility are listed below:
PrimeCare – Top 5 MS DRGs
Part II Written Assignment
Review the Case Mix Index figures in the table below.
Overall Case Mix Index FY 20xx
Facility Year 1 Year 2 Year 3
Hospital A 1.7694 1.9052 1.9689
Hospital B 1.5925 1.5554 1.7715
Hospital C 1.6443 1.7073 1.9003
Hospital D 1.5053 1.9471 1.8945
State Average 1.6667 1.7712 1.9085
a. Prepare a graphic representation that compares each of the hospital figures to the state average for each year.
b. Evaluate the data contained in the table. What types of conclusions can be drawn from this information about each hospital and the state average for each year? Prepare a short report (1 page) that evaluates the possible explanations as for why each facility’s overall CMIs were higher or lower that the state average for each year.