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The Clone-Censor-Weight Method in Pharmacoepidemiologic Research: Foundations and Methodological Implementation

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Abstract

Purpose of Review

Over the past two decades, cautions have repeatedly been issued about the potential for immortal time bias in observational studies. This bias is particularly relevant in fields that routinely leverage large secondary databases such as pharmacoepidemiology. A variety of study design and analysis tools exist to prevent immortal time bias. A newer approach, the clone-censor-weight method, successfully eliminates the possibility for immortal time while maintaining a target trial emulation framework. We review the rationale for the clone-censor-weight approach, outline the steps for implementation, compare the method to other tools for handling immortal time, and describe how the method has been used in a convenience sample of applied studies.

Recent Findings

The clone-censor-weight method offers distinct advantages over other methods for handling immortal time bias, namely the retention of a target trial emulation framework. The clone-censor-weight method has been used across numerous substantive areas within pharmacoepidemiology, with variation in how the method is implemented.

Summary

The clone-censor-weight method represents a rigorous approach for emulating a target trial and preventing immortal time bias. Many pharmacoepidemiologic studies would benefit from appropriate use of this method, though future work should illuminate the impact of different implementation choices.

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Authors and Affiliations

  1. Department of Pharmacy Systems, Outcomes and Policy, College of Pharmacy, University of Illinois-Chicago, 833 S. Wood St., 227A PHARM, MC 871, Chicago, IL, 60612, USA

    Charles E. Gaber, Kent A. Hanson, Sodam Kim & Todd A. Lee

  2. Center for Pharmacoeconomics and Pharmacoepidemiology & Pharmacoeconomic Research, College of Pharmacy, University of Illinois-Chicago, Chicago, IL, USA

    Charles E. Gaber & Todd A. Lee

  3. Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA

    Jennifer L. Lund

  4. Department of Epidemiology, Boston University School of Public Health, 715 Albany St, Boston, MA, 02118, USA

    Eleanor J. Murray

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  1. Charles E. Gaber
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  2. Kent A. Hanson
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  4. Jennifer L. Lund
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Contributions

C.G. searched the literature and wrote the main manuscript text. K.H. searched the literature, helped create table, and provided edits and comments during review of manuscript draft. S.K. searched the literature, helped create table, and provided edits and comments during review of manuscript draft. J.L. provided edits and comments during review of manuscript draft. T.L. provided edits and comments during review of manuscript draft. E.M. provided edits and comments during review, including drafting new content for the main manuscript text.

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Correspondence to Charles E. Gaber.

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Gaber, C.E., Hanson, K.A., Kim, S. et al. The Clone-Censor-Weight Method in Pharmacoepidemiologic Research: Foundations and Methodological Implementation. Curr Epidemiol Rep (2024). https://doi.org/10.1007/s40471-024-00346-2

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