Extended instrumental variables estimation for overall effects.
Extended instrumental variables estimation for overall effects.
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DOI：
10.2202/1557-4679.1082
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发表时间：
2008-04-07
期刊：
影响因子：
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通讯作者：
Feldman, Harold I
中科院分区：
文献类型：
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作者：
Joffe, Marshall M;Small, Dylan;Feldman, Harold I
我们考虑了一种扩展工具变量方法的方法，以估计治疗或暴露的总体效果。该方法是为仪器既影响感兴趣的治疗又影响受初级治疗影响的二级治疗的情况而设计的。我们证明，虽然工具变量方法可用于估计初级和次级治疗的联合效果，但它们本身不能用于估计初级治疗的总体效果。然而，工具变量方法可以与估计初级治疗对二级治疗的影响的方法结合使用，以估计初级治疗的总体效果。我们考虑扩展所提出的方法，以处理仪器效果的混淆、仪器效果由其他变量的中介、失效时间结果和时变的二次治疗。我们通过考虑血液透析患者血管通路类型的总体影响的估计来激发我们的讨论。
We consider a method for extending instrumental variables methods in order to estimate the overall effect of a treatment or exposure. The approach is designed for settings in which the instrument influences both the treatment of interest and a secondary treatment also influenced by the primary treatment. We demonstrate that, while instrumental variables methods may be used to estimate the joint effects of the primary and secondary treatments, they cannot by themselves be used to estimate the overall effect of the primary treatment. However, instrumental variables methods may be used in conjunction with approaches for estimating the effect of the primary on the secondary treatment to estimate the overall effect of the primary treatment. We consider extending the proposed methods to deal with confounding of the effect of the instrument, mediation of the effect of the instrument by other variables, failure-time outcomes, and time-varying secondary treatments. We motivate our discussion by considering estimation of the overall effect of the type of vascular access among hemodialysis patients.