Schwarzinger Michaël, Lanoë Jean-Louis, Nord Erik, Durand-Zaleski Isabelle
Service de Santé Publique, Hôpital Henri Mondor, Créteil, France.
Health Econ. 2004 Feb;13(2):171-81. doi: 10.1002/hec.808.
The person trade-off (PTO) is a technique for eliciting preferences for resource allocation across patient groups. In principle PTO responses should satisfy a requirement of multiplicative transitivity, i.e. that if people consider treatment of 1 in state A to be equivalent to treating 10 in state B, and 1 in state B to be equivalent to 10 in state C, then they should find 1 in state A equivalent to 100 in state C. Earlier studies addressing labelled diseases (specific diagnoses), have shown multiplicative intransitivity of the PTO responses. Our purpose was to test multiplicative transitivity in the case of health states described with the EuroQol instrument only and to find a possible framing effect such as the number of persons in the reference intervention.
Forty-four master degree students were asked to fill in a questionnaire addressing four chronic health states. Their task consisted in (1). ranking the states by severity, (2). valuing each of them by the means of the time trade-off, and (3). doing the PTO for all the 10 possible pairwise combinations of the four chronic states plus a fatal one. In a subsequent questionnaire the number of persons in the reference intervention in the PTO was increased from 10 to 100. Multiplicative transitivity was studied in subjects who demonstrated a willingness to trade off and consistency in ranking individual values.
None of the 39 subjects included satisfied a minimum multiplicative transitivity requirement in PTO responses. Internal consistency was not improved when the PTO involved health states close to each other in terms of severity, nor when the prevention of death was not the reference intervention. For the 22 subjects having answered both types of questionnaire, increasing the number of persons in the reference intervention did not improve multiplicative transitivity.
The PTO holds promise as a useful method for determining social preferences for priority setting, inasmuch as it captures distributive concerns that individual utility techniques such as the time trade-off do not address. But the lack of multiplicative transitivity in PTO responses is unsatisfactory, and ways to reduce this problem need to be explored.
个体权衡法（PTO）是一种用于引出患者群体间资源分配偏好的技术。原则上，PTO反应应满足乘法可传递性的要求，即如果人们认为在状态A下治疗1人等同于在状态B下治疗10人，且在状态B下治疗1人等同于在状态C下治疗10人，那么他们应认为在状态A下治疗1人等同于在状态C下治疗100人。早期针对特定疾病（具体诊断）的研究表明，PTO反应存在乘法非可传递性。我们的目的是仅在使用欧洲五维度健康量表描述健康状态的情况下测试乘法可传递性，并找出可能的框架效应，例如参考干预中的人数。
44名硕士研究生被要求填写一份针对四种慢性健康状态的问卷。他们的任务包括：（1）按严重程度对这些状态进行排序；（2）通过时间权衡法对每种状态进行估值；（3）对四种慢性状态加上一种致命状态的所有10种可能的两两组合进行PTO评估。在随后的一份问卷中，PTO中参考干预的人数从10人增加到100人。对表现出权衡意愿且在对个体价值排序上具有一致性的受试者进行乘法可传递性研究。
纳入研究的39名受试者中，无人在PTO反应中满足最低乘法可传递性要求。当PTO涉及严重程度相近的健康状态时，或者当预防死亡不是参考干预时，内部一致性并未得到改善。对于回答了两种问卷的22名受试者，增加参考干预中的人数并未改善乘法可传递性。
PTO有望成为一种有用的方法来确定社会对优先事项设定的偏好，因为它捕捉到了个体效用技术（如时间权衡法）未涉及的分配问题。但PTO反应缺乏乘法可传递性令人不满意，需要探索减少这一问题的方法。
