Date of this Version
The International Journal of Biostatistics
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.
The final publication is available at www.degruyter.com.
instrumental variables, casual inference
Joffe, M. M., Small, D. S., Ten Have, T., Brunelli, S., & Feldman, H. I. (2008). Extended Instrumental Variables Estimation for Overall Effects. The International Journal of Biostatistics, 4 (1), Retrieved from https://repository.upenn.edu/statistics_papers/450
Date Posted: 27 November 2017
This document has been peer reviewed.