代表性与外推：来自临床试验的证据

中文摘要

本文考察黑人患者临床试验入组率偏低的后果及其成因。我们构建了一个基于相似性的外推简单模型，该模型预测：当证据对接受治疗的群体更具代表性时，它与医生和患者决策的相关性更高。由此得到一个关键结论——某种药物对某一群体的感知获益，不仅取决于试验中的平均获益，还取决于该群体患者在试验入组者中所占的比例。在调查实验中，我们发现，为黑人患者提供诊疗服务的医生更愿意开具在具有代表性样本中检验过的药物，这一效应之大，足以消除观察到的新药处方率差距。当药物检验样本更具代表性时，黑人患者会对药物疗效作出更大幅度的信念更新，从而缩小黑人与白人患者在“药物能否如描述般起效”这一信念上的差距。尽管代表性数据具有上述益处，我们的理论框架与证据表明，从过去医学突破中获益更多的人群，在当前的入组成本更低，这导致证据基础中“谁被代表”呈现出持续性。

Abstract

This article examines the consequences and causes of low enrollment of Black patients in clinical trials. We develop a simple model of similarity-based extrapolation that predicts that evidence is more relevant for decision-making by physicians and patients when it is more representative of the group being treated. This generates the key result that the perceived benefit of a medicine for a group depends not only on the average benefit from a trial but also on the share of patients from that group who were enrolled in the trial. In survey experiments, we find that physicians who care for Black patients are more willing to prescribe drugs tested in representative samples, an effect substantial enough to close observed gaps in the prescribing rates of new medicines. Black patients update more on drug efficacy when the sample that the drug is tested on is more representative, reducing Black-white patient gaps in beliefs about whether the drug will work as described. Despite these benefits of representative data, our framework and evidence suggest that those who have benefited more from past medical breakthroughs are less costly to enroll in the present, leading to persistence in who is represented in the evidence base.