Disentangling WTP per QALY data: different analytical approaches, different answers

Area of Science:

• Health Economics
• Decision Analysis
• Public Health Policy

Background:

• Accurate valuation of health improvements is crucial for resource allocation in healthcare.
• Existing methods like time trade-off (TTO) and willingness-to-pay (WTP) are widely used but may yield divergent results.
• Understanding respondent heterogeneity is key to robust economic evaluations.

Purpose of the Study:

• To investigate the heterogeneity in health valuations between TTO and WTP methods in a general population sample.
• To assess the impact of different analytical strategies on willingness-to-pay per quality-adjusted life year (QALY) estimates.
• To identify areas for future research in preference elicitation and analysis.

Main Methods:

• A large random sample of the Danish general population was surveyed.
• Respondents used both time trade-off (TTO) and contingent valuation (CV) for willingness-to-pay (WTP) elicitation.
• Data analysis explored aggregated (ratios of means) versus disaggregated (means of ratios) approaches and regression models with a constant term.

Main Results:

• Significant heterogeneity was observed in respondents' relative valuations across TTO and WTP scales.
• Estimates of WTP per QALY were highly sensitive to the chosen analytical strategy.
• The choice between aggregated and disaggregated approaches, and the interpretation of the regression constant, markedly affected WTP estimates.

Conclusions:

• Respondent heterogeneity poses challenges for data analysis in health valuation studies.
• The analytical approach significantly influences WTP per QALY estimates, necessitating cautious interpretation.
• Future research should address respondent non-participation in TTO, the interpretation of regression constants, and methods for capturing preference heterogeneity.