iBMG/iMTA, Erasmus University Rotterdam, P.O. Box 1738, 3000 DR, Rotterdam, The Netherlands.
Qual Life Res. 2010 May;19(4):489-97. doi: 10.1007/s11136-010-9605-9. Epub 2010 Feb 12.
The linear and power QALY models require that people in Time Trade-off (TTO) exercises sacrifice the same proportion of lifetime to obtain a health improvement, irrespective of the absolute amount. However, evidence on these constant proportional trade-offs (CPTOs) is mixed, indicating that these versions of the QALY model do not represent preferences. Still, it may be the case that a more general version of the QALY model represents preferences. This version has the property that people want to sacrifice the same proportion of utilities of lifetime for a health improvement, irrespective of the amount of this lifetime.
We use a new method to correct TTO scores for utility of life duration and test whether decision makers trade off utility of duration and quality at the same rate irrespective of duration.
We find a robust violation of CPTO for both uncorrected and corrected TTO scores. Remarkably, we find higher values for longer durations, contrary to most previous studies. This represents the only study correcting for utility of life duration to find such a violation.
It seems that the trade-off of life years is indeed not so constantly proportional and, therefore, that health state valuations depend on durations.
线性和幂 QALY 模型要求在时间权衡（TTO）练习中，无论健康改善的绝对量如何，人们都要牺牲相同比例的寿命来获得健康改善。然而，关于这些恒定比例权衡（CPTO）的证据是混杂的，这表明这些 QALY 模型的版本并不能代表偏好。尽管如此，可能存在一种更通用的 QALY 模型来代表偏好。这个版本的特点是，无论寿命的数量如何，人们都希望为健康改善牺牲相同比例的寿命效用。
我们使用一种新方法来校正 TTO 分数的生命持续时间效用，并检验决策者是否以相同的速率权衡持续时间和质量效用，而与持续时间无关。
我们发现未经校正和校正后的 TTO 分数都存在严重违反 CPTO 的情况。值得注意的是，我们发现对于更长的持续时间，存在更高的价值，这与大多数先前的研究相反。这是唯一一项校正生命持续时间效用的研究，发现了这种违反情况。
似乎生命年限的权衡确实不是那么恒定比例的，因此，健康状态的估值取决于持续时间。
