Epidemiologic studies of adverse effects of anti-retroviral drugs: how well is statistical power reported

Authors

  • Scott D. Halpern MD, PhD,

    1. Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    2. Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    3. Center for Education and Research on Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    4. Center for Bioethics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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  • Todd D. Barton MD,

    1. Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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  • Robert Gross MD, MSCE,

    1. Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    2. Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    3. Center for Education and Research on Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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  • Sean Hennessy PharmD, PhD,

    1. Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    2. Center for Education and Research on Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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  • Jesse A. Berlin ScD,

    1. Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    2. Center for Education and Research on Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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  • Brian L. Strom MD, MPH

    Corresponding author
    1. Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    2. Center for Education and Research on Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    • Center for Clinical Epidemiology and Biostatistics, 824 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104-6021, USA.
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  • No conflict of interest was declared.

Abstract

Purpose

To determine whether there is a difference in average statistical power between pharmacoepidemiologic studies of anti-retroviral adverse drug effects (ADEs) sponsored by for-profit versus non-profit organizations.

Methods

We studied all published pharmacoepidemiologic studies of ADEs associated with the 15 anti-retroviral drugs approved through the end of 1999. A priori, the primary outcome was the power of each study to detect a clinically important difference in the risk for an adverse effect among patients exposed to the study drug(s). We could not evaluate this outcome because of the infrequent reporting of power calculations. We instead report the distribution of studies across a 5-tiered measure of adequacy of reporting of statistical power, as well as the sponsorship of these studies.

Results

Of 48 studies meeting our inclusion criteria, only 1 (2%) reported either a completed, a priori power calculation or sufficient details for readers to calculate the power to detect a pre-defined, clinically important effect. Thirty-five studies (73%) reported the minimum information required for sophisticated readers to determine the power to detect an event rate of interest to them; 6 additional studies (13%) reported confidence intervals around at least one summary effect measure and 6 (13%) provided no indication of power or uncertainty. Of the 41 studies for which sponsorship was determined, only 3 (7%) were sponsored by for-profit organizations.

Conclusions

The poor reporting of statistical power in this sample suggests a need for guidelines to improve the reporting of pharmacoepidemiologic studies of ADEs. Future research is needed to determine whether the observed paucity of industry-sponsored observational studies of anti-retroviral ADEs extends to other clinical areas, and if so, to identify the causes of this phenomenon. Copyright © 2004 John Wiley & Sons, Ltd.

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