Randomization-based Instrumental Variables methods for Binary outcomes with an Application to the ‘IMPROVE’ trial
针对随机对照试验中依从性不佳的情况，提出一种基于随机化推断的非参数工具变量方法，用于估计二元结局的依从者平均因果效应，并以主动脉瘤破裂修复手术的IMPROVE试验为例展示应用。
Summary In randomized controlled trials with non-adherence, instrumental variable (IV) methods are frequently used to report the complier average causal effect. With binary outcomes, many of the available IV estimation methods impose distributional assumptions. We develop a randomization-inference-based method of IV estimation for binary outcomes. The method is non-parametric and is based on Fisher's exact test, and estimates can be easily calculated from a set of 2×2 or 2×2×2 tables. Although we retain the standard IV identification assumptions for confidence regions and point estimates, the IV estimand under randomization inference is sample specific and does not assume that the randomized controlled trials participants are a random sample from the target population. We illustrate the method with the ‘IMPROVE’ trial that compares emergency endovascular versus open surgical repair for patients with ruptured aortic aneurysms.