The comparability and reliability of five health-state valuation methods

Area of Science:

• Health Economics
• Psychometrics
• Decision Analysis

Background:

• Accurate valuation of health states is crucial for health economics and policy.
• Existing methods for health state valuation vary in their reliability and comparability.
• Standard Gamble (SG), Time Trade-Off (TTO), Rating Scale (RS), Willingness-to-Pay (WTP), and Paired Comparisons (PC) are commonly used.

Purpose of the Study:

• To compare five health valuation methods based on convergent validity and reliability.
• To assess the comparability of different health valuation techniques.
• To evaluate the reliability of SG, TTO, RS, WTP, and PC methods.

Main Methods:

• 104 student volunteers performed valuation tasks using SG, TTO, RS, WTP, and PC.
• The EuroQol classification system generated 13 health state descriptions.
• Validity was assessed using the multitrait-multimethod (MTMM) approach; reliability was studied using Generalisability Theory and non-parametric methods.

Main Results:

• SG values were slightly higher than TTO values.
• Rating Scale (RS) values, after transformation, closely aligned with SG and TTO.
• Willingness-to-Pay (WTP) showed linear relationships with SG/TTO but had low reliability and high inconsistencies; Paired Comparisons (PC) yielded unstable results.

Conclusions:

• The Rating Scale (RS), with transformations, is a feasible, reliable, and comparable method for health state valuation.
• Parametric transformation functions support the use of RS alongside SG/TTO.
• Further data from a complete design are needed for a definitive judgment on Paired Comparisons (PC).