Kressel Laura M, Chapman Gretchen B
Department of Psychology, Rutgers University, Piscataway, New Jersey, USA.
Med Decis Making. 2007 May-Jun;27(3):299-310. doi: 10.1177/0272989X07300608.
Living wills are intended to preserve patient autonomy, but recent studies suggest that they do not always have their desired effect. One possible explanation is that living wills do not capture the authentic preferences of the patients who write them but instead reflect transient contextual effects on preferences.
Two experiments examined whether end-of-life treatment preferences expressed in a living will were influenced by the presence of default options.
College students participated in 2 Web-based questionnaire experiments (Ns = 182 and 51). Participants were randomly assigned to 1 of 2 or 3 default conditions.
In experiment 1, participants expressed significantly different treatment preferences in 3 normatively equivalent, check box-formatted living wills that were either positively worded ("indicate medical treatments you would want administered"), negatively worded ("indicate treatments you would want withheld"), or of forced-choice format (P = 0.01). Participants expressed a stronger preference to receive treatment in the negatively worded document than in the positively worded document as a consequence of preferring the default option in both cases. Participants in experiment 2 were also influenced by the presence of a default option, but this time, while writing narrative living wills after viewing 1 of 2 sample living wills. In this experiment, the sample living will represented the default preference. The participants' own living wills tended to express preferences similar to those in the sample (P = 0.0005).
The default manipulations in both experiments had potent but transient effects and influenced what participants wrote in their living wills but not their responses to later medical scenarios. Expression of end-of-life treatment preferences appears to be temporarily constructed from the decision-making context. These results have implications for surrogate decision making and the use of the living will as a tool to preserve patient autonomy.
生前预嘱旨在维护患者的自主权，但近期研究表明，它们并不总能产生预期效果。一种可能的解释是，生前预嘱并未体现撰写者的真实偏好，而是反映了偏好上的短暂情境效应。
两项实验检验了生前预嘱中表达的临终治疗偏好是否受默认选项的影响。
大学生参与了两项基于网络的问卷调查实验（样本量分别为182和51）。参与者被随机分配到两种或三种默认条件中的一种。
在实验1中，参与者在三种规范等效、复选框格式的生前预嘱中表达了显著不同的治疗偏好，这三种预嘱分别为积极措辞（“指明你希望接受的医疗治疗”）、消极措辞（“指明你希望不接受的治疗”）或强制选择格式（P = 0.01）。由于在两种情况下都偏好默认选项，参与者在消极措辞的文件中表达了比在积极措辞的文件中更强的接受治疗的偏好。实验2中的参与者也受到默认选项的影响，但这一次是在查看两份样本生前预嘱之一后撰写叙述性生前预嘱时。在该实验中，样本生前预嘱代表默认偏好。参与者自己的生前预嘱倾向于表达与样本中相似的偏好（P = 0.0005）。
两项实验中的默认操作都产生了强大但短暂的影响，影响了参与者在生前预嘱中所写的内容，但未影响他们对后续医疗场景的反应。临终治疗偏好的表达似乎是根据决策背景临时构建的。这些结果对替代决策以及将生前预嘱用作维护患者自主权的工具具有启示意义。
