Valuing Healthcare Goods and Services: A Systematic Review and Meta-Analysis on the WTA-WTP Disparity

Objective: The objective of this systematic review was to review the available evidence on the disparity between willingness to accept (WTA) and willingness to pay (WTP) for healthcare goods and services. Methods: A tiered approach consisting of (1) a systematic review, (2) an aggregate data meta-analysis, and (3) an individual participant data meta-analysis was used. MEDLINE, EMBASE, Scopus, Scisearch, and Econlit were searched for articles reporting both WTA and WTP for healthcare goods and services. Individual participant data were requested from the authors of the included studies. Results: Thirteen papers, reporting WTA and WTP from 19 experiments/subgroups, were included in the review. The WTA/WTP ratios reported in these papers, varied from 0.60 to 4.01, with means of 1.73 (median 1.31) for 15 estimates of the mean and 1.58 (median 1.00) for nine estimates of the median. Individual data obtained from six papers, covering 71.2% of the subjects included in the review, yielded an unadjusted WTA/WTP ratio of 1.86 (95% confidence interval 1.52–2.28) and a WTA/WTP ratio adjusted for age, sex, and income of 1.70 (95% confidence interval 1.42–2.02). Income category and age had a statistically significant effect on the WTA/WTP ratio. The approach to handling zero WTA and WTP values has a considerable impact on the WTA/WTP ratio found. Conclusions and Implications: The results of this study imply that losses in healthcare goods and services are valued differently from gains (ratio > 1), but that the degree of disparity found depends on the method used to obtain the WTA/WTP ratio, including the approach to zero responses. Irrespective of the method used, the ratios found in our meta-analysis are smaller than the ratios found in previous meta-analyses.