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See the attached file.

Case Mix Index & the DRG's

Under the Prospective Payment System (PPS), hospitals are paid a set fee for treating patients in a single DRG category, regardless of the actual cost of care for the individual patient.

Definition of Diagnosis-Related Group (DRG).The DRG is the inpatient classification that categorizes patients who are similar in terms of diagnoses & treatment, age, resources used & lengths of stay.

Definition of Case Mix Index (CMI)- CMI is the average of the sum of the relative weights(RWs) of all patients treated during a specific time period. Case Mix index formula is CMI= Total Relative Weight divided by the Total Volume


Attached is an excel spreadsheet. The 1st question is a simple DRG report which requires the determination of the Case Mix index.

This is a matter of determining the total relative weight & the total volume.& then calculating the CMI using the formula CMI=TRW/TV

Table 1: 1st multiply DRG identifier A by taking the relative weight of A x the volume ( total number of patients seen) DRG A 2.133 x 15 =31.995. Do that for each DRG identifier & then total. This total is the Total Relative Weight.
2nd Total the number of patients seen = the Total Volume.
3rd determine Case Mix Index with these numbers above, using formula provided. CMI=TRW/TV

Table 2 & 3 : Determine the CMI . Most of the calculation totals have already been completed for Total Relative Weight. Complete the missing TRW. The listed information in each Table is done so purposely . Why? Because it not uncommon to take your board certification exams & they will give you TMI- learn how to weed out what is NOT needed.

Hint: Use the Auto Sum (Greek E symbol) to determine TV & TRW

Table 4 determine CMI.

Lastly; list the four steps to determine the MS-DRG & describe these steps.


Solution Preview

Please download the attachment in Excel format for better prints.

A 2.133 15 31.995
B 2.172 12 26.064
C 4.111 11 45.221
D 4.175 10 41.75 CMI= TRW/TV 3.021458333
48 145.03

MS-DRG MS-DRG Title Volume -4th qtr 2013 MDC TYPE RW Total RW
65 Intracranial hemorrhage or cerebral infarction w CC 128 1 MED 1.158 148.224
66 Intracranial hemorrhage or cerebral infarction w/o CC/MCC 102 1 MED 0.8223 83.8746
69 Transient ischemia 110 1 MED 0.7289 80.179
189 Pulmonary edema & respiratory failure 114 4 MED 1.3455 153.387
191 Chronic obstructive pulmonary disease w CC 131 4 MED 0.9622 126.0482
192 Chronic obstructive pulmonary disease w/o CC/MCC 218 4 MED 0.7175 156.415
194 Simple pneumonia & pleurisy w CC 295 4 MED 0.9976 294.292
195 Simple pneumonia & pleurisy w/o CC/MCC 172 4 MED 0.7095 122.034
1270 1164.4538

Solution Summary

DRG stands for Diagnosis related group. DRG grouping is a method used to assign a DRG based on diagnoses being made and procedures performed for a particular patient's case. The solution is attached in Excel.