Weighting case mix groups: the fatal flaw in resource intensity weights

Area of Science:

• Health Services Research
• Health Economics
• Healthcare Management

Background:

• Resource Intensity Weights (RIWs) are used for Canadian Case Mix Groups (CMGs).
• RIWs are calculated using American Diagnosis Related Group (DRG) weights and Canadian average-length-of-stay data.
• Concerns exist regarding the accuracy and Canadianization of these RIWs.

Purpose of the Study:

• To evaluate the relationship between RIWs and CMG costs in Canadian healthcare.
• To demonstrate the deficiencies in the current RIW calculation method.
• To propose alternative approaches for case mix analysis and fiscal planning in Canadian healthcare.

Main Methods:

• Analysis of Resource Intensity Weights (RIWs) for Case Mix Groups (CMGs).
• Utilized American Diagnosis Related Group (DRG) weights and Canadian average-length-of-stay data.
• Employed simplified graphical examples to illustrate the relationship between RIWs and CMG costs.

Main Results:

• The calculation of RIWs does not accurately "Canadianize" DRG weights, leading to randomization.
• A significant lack of correlation was demonstrated between RIWs and actual CMG costs.
• The study highlights the deficiencies in using current RIWs for accurate cost allocation.

Conclusions:

• The concept of weighted CMGs is fundamentally sound, but current RIW methodology is flawed.
• Canadian healthcare institutions may consider using unadulterated American DRGs for case mix analysis and fiscal planning.
• Implementation of Management Information System (MIS)-level reporting and a robust domestic database are needed for improved Canadian case mix analysis.