Ubel P A, Loewenstein G, Scanlon D, Kamlet M
Veterans Affairs Medical Center, Philadelphia, PA, USA.
Health Policy. 1998 Jan;43(1):33-44. doi: 10.1016/s0168-8510(97)00077-8.
Previous studies have shown a discrepancy between common utility elicitation methods, such as rating scale (RS) elicitations, and person trade-off (PTO) elicitations. This discrepancy has generally been felt to be due to the fact that RS elicitations ask people to compare conditions to each other in terms of numbers on a visual rating scale, while PTO elicitations ask people to think in terms of numbers of people needing to be treated. However, there are three other cognitive differences between PTO and RS elicitations that might contribute to the discrepancy: In PTO elicitations, as opposed to RS elicitations: (1) people are asked to think about how conditions affect people other than themselves; (2) people are asked to think about the benefit of treating conditions; and (3) people are asked to chose who to treat among patients with different conditions. In this study, we attempt to determine whether any of three cognitive differences contribute to the discrepancy between RS and PTO utility elicitations. We randomized prospective jurors to receive one of several survey versions in which we manipulated the RS and PTO elicitations to reduce the differences between them, while preserving their underlying structure. In the RS-self survey, we asked subjects to rate a health condition on a scale from 0 to 100 as if they had the condition. In the RS-other survey, we asked people to rate the health condition as if someone else had it. In the RS-cure survey, we asked subjects to rate the benefits of curing someone else of the health condition. In the PTO-comparison survey, we asked people to determine equivalent numbers of people needing to be cured of two conditions in order to produce equal benefits. In the PTO-choice survey, we presented people with a budget constraint and asked them to determine equivalent numbers of people needing to be cured of two conditions to help decide which group should be treated within the budget constraint. Two hundred and twenty two subjects completed surveys. Median utilities for health conditions were higher in the two PTO elicitations than in the three RS elicitations. There were no differences in utilities across the two PTO surveys, nor across the three RS surveys. In addition, the PTO elicitations allowed people to make finer distinctions among non-life threatening conditions than did the RS elicitations. The discrepancy between RS and PTO elicitations cannot be explained by shifting subjects attentions from themselves to others, nor from conditions to the benefit of treating conditions. Instead, the discrepancy occurs because of the general format of RS and PTO elicitations.
以往的研究表明，常见的效用诱导方法之间存在差异，例如评分量表（RS）诱导法和个人权衡（PTO）诱导法。人们普遍认为这种差异是由于以下事实：RS诱导法要求人们根据视觉评分量表上的数字相互比较不同状况，而PTO诱导法要求人们从需要治疗的人数角度进行思考。然而，PTO和RS诱导法之间还存在其他三种认知差异，可能导致这种差异：与RS诱导法不同，在PTO诱导法中：（1）要求人们思考不同状况如何影响他人而非自己；（2）要求人们思考治疗不同状况的益处；（3）要求人们在患有不同状况的患者中选择治疗对象。在本研究中，我们试图确定这三种认知差异中的任何一种是否会导致RS和PTO效用诱导法之间的差异。我们将未来的陪审员随机分组，让他们接受几种调查问卷版本中的一种，在这些问卷中，我们对RS和PTO诱导法进行了调整，以减少它们之间的差异，同时保留其基本结构。在RS-自我调查问卷中，我们要求受试者对一种健康状况在0到100的量表上进行评分，就好像他们患有这种状况一样。在RS-他人调查问卷中，我们要求人们对一种健康状况进行评分，就好像是别人患有这种状况一样。在RS-治愈调查问卷中，我们要求受试者对治愈别人的这种健康状况的益处进行评分。在PTO-比较调查问卷中，我们要求人们确定治愈两种状况所需的等效人数，以便产生同等的益处。在PTO-选择调查问卷中，我们给人们设定一个预算限制，并要求他们确定治愈两种状况所需的等效人数，以帮助决定在预算限制内应该治疗哪一组。222名受试者完成了调查问卷。两种PTO诱导法中健康状况的效用中位数高于三种RS诱导法中的效用中位数。两种PTO调查问卷之间以及三种RS调查问卷之间的效用没有差异。此外，与RS诱导法相比，PTO诱导法能让人们在非危及生命的状况之间做出更细微的区分。RS和PTO诱导法之间的差异既不能通过将受试者的注意力从自身转移到他人来解释，也不能通过从状况转移到治疗状况的益处来解释。相反，这种差异是由于RS和PTO诱导法的总体形式导致的。
