Willingness to Pay per QALY: A Systematic Review of Demand-Side Valuations with a Focus on Age and Disease Severity

Willingness-to-pay (WTP) studies offer a demand-side perspective on the monetary value of health gains, typically expressed as WTP per quality-adjusted life year (WTP/Q). These estimates can complement supply-side cost-effectiveness thresholds (CETs) and inform whether healthcare budgets align with public preferences. However, existing thresholds often overlook heterogeneity by condition or population characteristics.

This study sought to systematically review literature on WTP/Q estimates derived from stated preference methods by (i) mapping the broader landscape of demand-side valuations and (ii) synthesizing how WTP/Q varies by both respondent and scenario-assigned age and disease severity in general-health contexts.

A systematic review was conducted across Medline, Embase, and EconLit, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Eligible studies estimated the monetary value of a quality-adjusted life year (QALY) from a societal, demand-side perspective. We first conducted a broad narrative mapping of all included studies to describe methodological characteristics and contextual diversity. We then focused on a subset of studies using general-health scenarios to explore how willingness to pay per QALY varied by age and severity. A structured four-axis framework was applied to distinguish between respondent characteristics and scenario-assigned attributes. Data were classified and tabulated. A formal quality assessment was conducted across the full set of studies using the National Institutes of Health (NIH) tool.

A total of 67 studies met inclusion criteria. Most originated from high-income countries and used contingent valuation or discrete choice experiments. Among general-health studies, WTP/Q decreased with respondents' actual age in 49% of studies and increased with respondents' own health severity in 79%. In studies assessing scenario-assigned attributes, WTP/Q increased with hypothetical disease severity in 91% of studies and decreased with scenario-assigned age in 83%. Substantial heterogeneity was observed in elicitation methods, framing, and utility measurement.

The findings support the need for condition- and population-specific WTP thresholds, as valuations appear to vary depending on the nature of the health gain and the characteristics of the beneficiary-whether real or hypothetical.