Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project.

<h4>Purpose</h4>Observational studies using routinely collected data are faced with a number of potential shortcomings that can bias their results. Many methods rely on controlling for measured and unmeasured confounders. In this work, we investigate the use of instrumental variables (IV...

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Autores principales:	Monia Ezzalfani, Raphaël Porcher, Alexia Savignoni, Suzette Delaloge, Thomas Filleron, Mathieu Robain, David Pérol, ESME Group
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/f84c61bc31f24e18be5b443d6772f547
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spelling	oai:doaj.org-article:f84c61bc31f24e18be5b443d6772f5472021-12-02T20:14:36ZAddressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project.1932-620310.1371/journal.pone.0255017https://doaj.org/article/f84c61bc31f24e18be5b443d6772f5472021-01-01T00:00:00Zhttps://doi.org/10.1371/journal.pone.0255017https://doaj.org/toc/1932-6203<h4>Purpose</h4>Observational studies using routinely collected data are faced with a number of potential shortcomings that can bias their results. Many methods rely on controlling for measured and unmeasured confounders. In this work, we investigate the use of instrumental variables (IV) and quasi-trial analysis to control for unmeasured confounders in the context of a study based on the retrospective Epidemiological Strategy and Medical Economics (ESME) database, which compared overall survival (OS) with paclitaxel plus bevacizumab or paclitaxel alone as first-line treatment in patients with HER2-negative metastatic breast cancer (MBC).<h4>Patients and methods</h4>Causal interpretations and estimates can be made from observation data using IV and quasi-trial analysis. Quasi-trial analysis has the same conceptual basis as IV, however, instead of using IV in the analysis, a "superficial" or "pseudo" randomized trial is used in a Cox model. For instance, in a multicenter trial, instead of using the treatment variable, quasi-trial analysis can consider the treatment preference in each center, which can be informative, and then comparisons of results between centers or clinicians can be informative.<h4>Results</h4>In the original analysis, the OS adjusted for major factors was significantly longer with paclitaxel and bevacizumab than with paclitaxel alone. Using the center-treatment preference as an instrument yielded to concordant results. For the quasi-trial analysis, a Cox model was used, adjusted on all factors initially used. The results consolidate those obtained with a conventional multivariate Cox model.<h4>Conclusion</h4>Unmeasured confounding is a major concern in observational studies, and IV or quasi-trial analysis can be helpful to complement analysis of studies of this nature.Monia EzzalfaniRaphaël PorcherAlexia SavignoniSuzette DelalogeThomas FilleronMathieu RobainDavid PérolESME GroupPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 16, Iss 9, p e0255017 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Monia Ezzalfani Raphaël Porcher Alexia Savignoni Suzette Delaloge Thomas Filleron Mathieu Robain David Pérol ESME Group Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project.
description	<h4>Purpose</h4>Observational studies using routinely collected data are faced with a number of potential shortcomings that can bias their results. Many methods rely on controlling for measured and unmeasured confounders. In this work, we investigate the use of instrumental variables (IV) and quasi-trial analysis to control for unmeasured confounders in the context of a study based on the retrospective Epidemiological Strategy and Medical Economics (ESME) database, which compared overall survival (OS) with paclitaxel plus bevacizumab or paclitaxel alone as first-line treatment in patients with HER2-negative metastatic breast cancer (MBC).<h4>Patients and methods</h4>Causal interpretations and estimates can be made from observation data using IV and quasi-trial analysis. Quasi-trial analysis has the same conceptual basis as IV, however, instead of using IV in the analysis, a "superficial" or "pseudo" randomized trial is used in a Cox model. For instance, in a multicenter trial, instead of using the treatment variable, quasi-trial analysis can consider the treatment preference in each center, which can be informative, and then comparisons of results between centers or clinicians can be informative.<h4>Results</h4>In the original analysis, the OS adjusted for major factors was significantly longer with paclitaxel and bevacizumab than with paclitaxel alone. Using the center-treatment preference as an instrument yielded to concordant results. For the quasi-trial analysis, a Cox model was used, adjusted on all factors initially used. The results consolidate those obtained with a conventional multivariate Cox model.<h4>Conclusion</h4>Unmeasured confounding is a major concern in observational studies, and IV or quasi-trial analysis can be helpful to complement analysis of studies of this nature.
format	article
author	Monia Ezzalfani Raphaël Porcher Alexia Savignoni Suzette Delaloge Thomas Filleron Mathieu Robain David Pérol ESME Group
author_facet	Monia Ezzalfani Raphaël Porcher Alexia Savignoni Suzette Delaloge Thomas Filleron Mathieu Robain David Pérol ESME Group
author_sort	Monia Ezzalfani
title	Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project.
title_short	Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project.
title_full	Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project.
title_fullStr	Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project.
title_full_unstemmed	Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project.
title_sort	addressing the issue of bias in observational studies: using instrumental variables and a quasi-randomization trial in an esme research project.
publisher	Public Library of Science (PLoS)
publishDate	2021
url	https://doaj.org/article/f84c61bc31f24e18be5b443d6772f547
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Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project.

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