Indexes of severity: underlying concepts

Area of Science:

• Health Services Research
• Ordinal Ranking Theory
• Health Status Measurement

Background:

• Existing health severity indexes are widely used in health services research.
• Previous research has not fully explored the theoretical underpinnings of these severity indexes.
• The relationship between different severity indexes and broader health status measures remains unclear.

Purpose of the Study:

• To demonstrate that six common health severity indexes are specific instances of additive value functions.
• To identify and discuss the deficiencies of these severity indexes based on the properties of additive value functions.
• To explore the implications of additive value formulations for the larger class of health status indexes.

Main Methods:

• Comparative analysis of six existing health severity indexes.
• Application of ordinal ranking function theory, specifically additive value functions.
• Evaluation of index properties against the requirements of additive value functions.

Main Results:

• Six prominent health severity indexes were identified as special cases of additive value functions.
• Specific deficiencies were found in each of the analyzed severity indexes.
• The properties of additive value functions provide a framework for understanding and improving health status indexes.

Conclusions:

• Additive value functions offer a unifying theoretical framework for understanding health severity indexes.
• Addressing the identified deficiencies can lead to more robust and accurate health status measures.
• This research provides insights relevant to the development and refinement of health status indexes in health services research.