Improving the reporting of pragmatic trials: an extension of the CONSORT statement

Merrick Zwarenstein, Shaun Treweek, Joel J. Gagnier, Douglas G. Altman, Sean Tunis, Brian Haynes, Andrew D. Oxman, David Moher, CONSORT Grp, Pragmatic Trials Healthcare Practi

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    Abstract

    Background The CONSORT statement is intended to improve reporting of randomised controlled trials and focuses on minimising the risk of bias ( internal validity). The applicability of a trial's results ( generalisability or external validity) is also important, particularly for pragmatic trials. A pragmatic trial ( a term first used in 1967 by Schwartz and Lellouch) can be broadly defined as a randomised controlled trial whose purpose is to inform decisions about practice. This extension of the CONSORT statement is intended to improve the reporting of such trials and focuses on applicability.

    Methods At two, two- day meetings held in Toronto in 2005 and 2008, we reviewed the CONSORT statement and its extensions, the literature on pragmatic trials and applicability, and our experiences in conducting pragmatic trials.

    Recommendations We recommend extending eight CONSORT checklist items for reporting of pragmatic trials: the background, participants, interventions, outcomes, sample size, blinding, participant flow, and generalisability of the findings. These extensions are presented, along with illustrative examples of reporting, and an explanation of each extension. Adherence to these reporting criteria will make it easier for decision makers to judge how applicable the results of randomised controlled trials are to their own conditions. Empirical studies are needed to ascertain the usefulness and comprehensiveness of these CONSORT checklist item extensions. In the meantime we recommend that those who support, conduct, and report pragmatic trials should use this extension of the CONSORT statement to facilitate the use of trial results in decisions about health care.

    Pragmatic trials are designed to inform decisions about practice, but poor reporting can reduce their usefulness. The CONSORT and Practihc groups describe modifications to the CONSORT guidelines to help readers assess the applicability of the results

    Randomised controlled trials are used to assess the benefits and harms of interventions in health care. If conducted properly, they minimise the risk of bias ( threats to internal validity), particularly selection bias.(1 2) There is, however, considerable evidence that trials are not always well reported, (3 4) and this can be associated with bias, such as selective reporting of outcomes.(5)

    The usefulness of a trial report also depends on the clarity with which it details the relevance of its interventions, participants, outcomes, and design to the clinical, health service, or policy question it examines. Furthermore, a trial may be valid and useful in the healthcare setting in which it was conducted but have limited applicability (also known as generalisability or external validity) beyond this because of differences between the trial setting and other settings to which its results are to be extrapolated.

    Schwartz and Lellouch(6) coined the terms " pragmatic" to describe trials designed to help choose between options for care, and " explanatory" to describe trials designed to test causal research hypotheses - for example, that an intervention causes a particular biological change. Table 1+ shows some key differences between explanatory and pragmatic trials. Table 2+ compares a trial that was highly explanatory in attitude(7) with one that was highly pragmatic.(8) There is a continuum rather than a dichotomy between explanatory and pragmatic trials. In fact, Schwartz and Lellouch characterised pragmatism as an attitude to trial design rather than a characteristic of the trial itself. The pragmatic attitude favours design choices that maximise applicability of the trial's results to usual care settings, rely on unarguably important outcomes such as mortality and severe morbidity, and are tested in a wide range of participants.(9) (10) (11) As Schwartz and Lellouch wrote: " Most trials done hitherto have adopted the explanatory approach without question; the pragmatic approach would often have been more justifiable."

    Original languageEnglish
    Article numbera2390
    Pages (from-to)-
    Number of pages12
    JournalBMJ
    Volume337
    DOIs
    Publication statusPublished - 11 Nov 2008

    Cite this

    Zwarenstein, M., Treweek, S., Gagnier, J. J., Altman, D. G., Tunis, S., Haynes, B., Oxman, A. D., Moher, D., & CONSORT Grp, Pragmatic Trials Healthcare Practi (2008). Improving the reporting of pragmatic trials: an extension of the CONSORT statement. BMJ, 337, -. [a2390]. https://doi.org/10.1136/bmj.a2390