Department of Health Management and Health Economics, University of Oslo, Oslo, Norway.
Health Services Research Centre, Akershus University Hospital, Lørenskog, Norway.
Value Health. 2020 Apr;23(4):487-494. doi: 10.1016/j.jval.2019.10.003. Epub 2019 Dec 16.
The EQ-5D-5L valuation protocol recommends combining time trade-off (TTO) and discrete choice experiments (DCEs). DCEs that include a duration attribute (DCE) allow modeling on the quality-adjusted life-year scale. Because the choice sequence in a TTO can be construed as a series of DCE, we used data from a single TTO study to investigate the extent to which DCE values match TTO values when based on identical preferences.
In a TTO design in which a fixed set of choices were administered without termination at preference indifference, 202 individuals each valued 10 EQ-5D health states. From identified indifference points, we estimated three sets of TTO values: (i) plotting means and (ii) applying censored regressions at -1 and 1. Using all strict preferences, we (iii) estimated DCE values with a logit model and a bootstrap procedure.
Estimated DCE and TTO values agreed well at the severe end of the quality-adjusted life-year scale, but with decreasing severity, DCE values were higher than TTO-values, with the difference peaking at 0.37 for the mildest health state. Left-censoring TTO values at -1 worsen the agreement for the worst health states and did not affect health states. Right censoring at 1 improved the agreement for mild states.
TTO and the DCE values estimated from the same preference data diverged, with increasing difference for milder health states. Although the values converged when applying censored regression at +1, we question the validity of this adjustment.
EQ-5D-5L 估值方案建议将时间权衡（TTO）和离散选择实验（DCE）相结合。包含持续时间属性的 DCE（DCE）允许在质量调整生命年（QALY）尺度上进行建模。由于 TTO 中的选择序列可以被解释为一系列 DCE，因此我们使用来自单个 TTO 研究的数据来研究当基于相同偏好时，DCE 值与 TTO 值匹配的程度。
在 TTO 设计中，固定的一组选择在偏好无差异时没有终止，202 名个体分别对 10 个 EQ-5D 健康状况进行了估值。从确定的无差异点出发，我们估计了三组 TTO 值：（i）绘制平均值和（ii）在-1 和 1 处应用截尾回归。使用所有严格偏好，我们（iii）使用对数模型和 bootstrap 程序估计了 DCE 值。
在 QALY 尺度的严重端，估计的 DCE 和 TTO 值非常吻合，但随着严重程度的降低，DCE 值高于 TTO 值，在最轻微的健康状态下，差异达到 0.37。将 TTO 值左截尾到-1 会降低最差健康状态的一致性，而不会影响健康状态。右截尾到 1 会提高轻度状态的一致性。
TTO 和从相同偏好数据中估计的 DCE 值存在差异，随着更轻微的健康状态的差异逐渐增大。尽管在应用+1 处的截尾回归时，值趋于一致，但我们对这种调整的有效性表示质疑。
