Introduction

Preference-based instruments measuring health status express the value of specific health states in a single number. One method used is time trade-off (TTO). Health-status values are key elements in calculating quality-adjusted life years (QALYs) and are pertinent for resource allocation. Since they are used in economic evaluations of healthcare, searching for a theoretical foundation of TTO in economics is justified.

Area covered

This paper provides an overview of TTO, including its relation to economic theory, and discusses biases and distortions, compiled from recent and older research. Inconsistencies between TTO and random utility theory were detected; The TTO is confounded by time preferences and by respondents’ life expectancies. TTO is cognitively challenging, therefore guidance during the interviews is needed, producing interview effects. TTO does not measure one thing at a time, nor are the values independent of other states that are being valued in the same task. That is, TTO does not exhibit theoretical measurement properties such as unidimensionality and the invariance principle.

Expert opinion

We conclude that the TTO may be a pragmatic method of eliciting health state values, but the limitations in regard to measurement theory and practical elicitation problems makes it prone to inconsistencies and arbitrariness.

中文翻译：

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时间权衡方法概述：概念、基础和对健康价值扭曲因素的评估。

介绍

测量健康状况的基于偏好的仪器以单个数字表示特定健康状况的价值。使用的一种方法是时间权衡（TTO）。健康状况值是计算质量调整生命年 (QALY) 的关键要素，与资源分配相关。由于它们被用于医疗保健的经济评估，因此在经济学中寻找 TTO 的理论基础是有道理的。

覆盖面积

本文概述了 TTO，包括其与经济理论的关系，并讨论了根据近期和较早研究汇编的偏见和扭曲。检测到 TTO 与随机效用理论之间的不一致；TTO 受到时间偏好和受访者预期寿命的影响。TTO 在认知上具有挑战性，因此需要在面试期间进行指导，从而产生面试效果。TTO 不会一次测量一件事，这些值也不会独立于在同一任务中被评估的其他状态。也就是说，TTO 不表现出理论测量特性，例如单维性和不变性原理。

专家意见

我们得出的结论是，TTO 可能是一种引出健康状态值的实用方法，但在测量理论和实际启发问题方面的局限性使其容易出现不一致和任意性。