Newcastle University Business School, Newcastle upon Tyne, UK.
DaCHE, Department of Public Health, University of Southern Denmark, Odense, Denmark.
Health Econ. 2021 May;30(5):923-931. doi: 10.1002/hec.4236. Epub 2021 Feb 10.
It is well established that the underlying theoretical assumptions needed to obtain a constant proportional trade-off between a quality adjusted life year (QALY) and willingness to pay (WTP) are restrictive and often empirically violated. In this paper, we set out to investigate whether the proportionality conditions (in terms of scope insensitivity and severity independence) can be satisfied when data is restricted to include only respondents who pass certain consistency criteria. We hypothesize that the more we restrict the data, the better the compliance with the requirement of constant proportional trade-off between WTP and QALY. We revisit the Danish data from the European Value of a QALY survey eliciting individual WTP for a QALY (WTP-Q). Using a "chained approach" respondents were first asked to value a specified health state using the standard gamble (SG) or the time-trade-off (TTO) approach and subsequently asked their WTP for QALY gains of 0.05 and 0.1 (tailored according to the respondent's SG/TTO valuation). Analyzing the impact of the different exclusion criteria on the two proportionality conditions, we find strong evidence against a constant WTP-Q. Restricting our data to include only respondents who pass the most stringent consistency criteria does not impact on the performance of the proportionality conditions for WTP-Q.
人们已经充分认识到，获得质量调整生命年（QALY）和支付意愿（WTP）之间恒定比例权衡所需的基本理论假设具有限制性，并且经常在经验上被违反。在本文中，我们着手研究当数据仅限于包括通过某些一致性标准的受访者时，比例条件（在范围无敏感性和严重程度独立性方面）是否可以得到满足。我们假设，我们对数据的限制越多，WTP 和 QALY 之间恒定比例权衡的要求就越符合要求。我们重新审视了来自欧洲 QALY 价值调查的丹麦数据，该调查征集了个人对 QALY 的支付意愿（WTP-Q）。使用“链式方法”，首先要求受访者使用标准博弈（SG）或时间权衡（TTO）方法对特定健康状况进行估值，然后要求他们支付 0.05 和 0.1 的 QALY 收益（根据受访者的 SG/TTO 估值量身定制）。分析不同排除标准对两个比例条件的影响，我们发现有强有力的证据表明 WTP-Q 不是恒定的。将我们的数据仅限于仅包括通过最严格一致性标准的受访者，不会影响 WTP-Q 的比例条件的性能。
