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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
PURPOSE: 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 a...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8443058/ https://www.ncbi.nlm.nih.gov/pubmed/34525119 http://dx.doi.org/10.1371/journal.pone.0255017 |
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author | Ezzalfani, Monia Porcher, Raphaël Savignoni, Alexia Delaloge, Suzette Filleron, Thomas Robain, Mathieu Pérol, David |
author_facet | Ezzalfani, Monia Porcher, Raphaël Savignoni, Alexia Delaloge, Suzette Filleron, Thomas Robain, Mathieu Pérol, David |
author_sort | Ezzalfani, Monia |
collection | PubMed |
description | PURPOSE: 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). PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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 | Online Article Text |
id | pubmed-8443058 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-84430582021-09-16 Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project Ezzalfani, Monia Porcher, Raphaël Savignoni, Alexia Delaloge, Suzette Filleron, Thomas Robain, Mathieu Pérol, David PLoS One Research Article PURPOSE: 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). PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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. Public Library of Science 2021-09-15 /pmc/articles/PMC8443058/ /pubmed/34525119 http://dx.doi.org/10.1371/journal.pone.0255017 Text en © 2021 Ezzalfani et al https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
spellingShingle | Research Article Ezzalfani, Monia Porcher, Raphaël Savignoni, Alexia Delaloge, Suzette Filleron, Thomas Robain, Mathieu Pérol, David Addressing the issue of bias in observational studies: Using instrumental variables and a quasi-randomization trial in an ESME research project |
title | 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_short | 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 |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8443058/ https://www.ncbi.nlm.nih.gov/pubmed/34525119 http://dx.doi.org/10.1371/journal.pone.0255017 |
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