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Assessing the magnitude of reporting bias in trials of homeopathy: ...meta-analysis, 2022, Gartlehner et al

Discussion in 'Other health news and research' started by Ravn, Mar 20, 2022.

  1. Ravn

    Ravn Senior Member (Voting Rights)

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    Aotearoa New Zealand
    EDIT: title was too long, here's the full citation:

    Gartlehner G, Emprechtinger R, Hackl M, et al

    Assessing the magnitude of reporting bias in trials of homeopathy: a cross-sectional study and meta-analysis

    BMJ Evidence-Based Medicine Published Online First: 15 March 2022. doi: 10.1136/bmjebm-2021-111846​


    Abstract


    Objectives To assess the magnitude of reporting bias in trials assessing homeopathic treatments and its impact on evidence syntheses.

    Design A cross-sectional study and meta-analysis. Two persons independently searched Clinicaltrials.gov, the EU Clinical Trials Register and the International Clinical Trials Registry Platform up to April 2019 to identify registered homeopathy trials. To determine whether registered trials were published and to detect published but unregistered trials, two persons independently searched PubMed, Allied and Complementary Medicine Database, Embase and Google Scholar up to April 2021. For meta-analyses, we used random effects models to determine the impact of unregistered studies on meta-analytic results.

    Main outcomes and measures We report the proportion of registered but unpublished trials and the proportion of published but unregistered trials. We also assessed whether primary outcomes were consistent between registration and publication. For meta-analyses, we used standardised mean differences (SMDs).

    Results
    Since 2002, almost 38% of registered homeopathy trials have remained unpublished, and 53% of published randomised controlled trials (RCTs) have not been registered. Retrospective registration was more common than prospective registration. Furthermore, 25% of primary outcomes were altered or changed compared with the registry. Although we could detect a statistically significant trend toward an increase of registrations of homeopathy trials (p=0.001), almost 30% of RCTs published during the past 5 years had not been registered.

    A meta-analysis stratified by registration status of RCTs revealed substantially larger treatment effects of unregistered RCTs (SMD: −0.53, 95% CI −0.87 to −0.20) than registered RCTs (SMD: −0.14, 95% CI −0.35 to 0.07).

    Conclusions Registration of published trials was infrequent, many registered trials were not published and primary outcomes were often altered or changed. This likely affects the validity of the body of evidence of homeopathic literature and may overestimate the true treatment effect of homeopathic remedies.

    Open access: https://ebm.bmj.com/content/early/2022/01/30/bmjebm-2021-111846
     
  2. Ravn

    Ravn Senior Member (Voting Rights)

    Messages:
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    Location:
    Aotearoa New Zealand
    Have only read the abstract.

    I don't expect anyone here will be surprised by the findings but posting because wondering if a similar paper exists or would be useful for demonstrating the low quality of ME-style BPS research?

    Of course NICE assessed the BPS studies and found them wanting but would it be worth somebody's effort to publish a paper similar to the homeopathy one that just lists how many studies didn't pre-register, changed primary outcomes, etc.?

    Or have we reached a point where we can move beyond that?
     
  3. Trish

    Trish Moderator Staff Member

    Messages:
    51,871
    Location:
    UK
    They're still doing them, including now for Long Covid. So definitely not too late. It's a pity this study didn't go a step further and assess the number of trials with flawed methods, like unblinded, subjective etc and very short time spans.
     
    shak8, Ravn, DokaGirl and 5 others like this.

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