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. 2024 Nov 27;11(11):MR000011.
doi: 10.1002/14651858.MR000011.pub3.

Time to publication for results of clinical trials

Marian G Showell  1 , Sammy Cole  1 , Mike J Clarke  2 , Nicholas J DeVito  3 , Cindy Farquhar  1 , Vanessa Jordan  1
Affiliations

Time to publication for results of clinical trials

Marian G Showell et al. Cochrane Database Syst Rev. .

Abstract

Background: Researchers conducting trials have a responsibility to publish the results of their work in a peer-reviewed journal, and failure to do so may introduce bias that affects the accuracy of available evidence. Moreover, failure to publish results constitutes research waste.

Objectives: To systematically review research reports that followed clinical trials from their inception and their investigated publication rates and time to publication. We also aimed to assess whether certain factors influenced publication and time to publication.

Search methods: We identified studies by searching MEDLINE, Embase, Epistemonikos, the Cochrane Methodology Register (CMR) and the database of the US Agency for Healthcare Research and Quality (AHRQ), from inception to 23 August 2023. We also checked reference lists of relevant studies and contacted experts in the field for any additional studies.

Selection criteria: Studies were eligible if they tracked the publication of a cohort of clinical trials and contained analyses of any aspect of the publication rate or time to publication of these trials.

Data collection and analysis: Two review authors performed data extraction independently. We extracted data on the prevalence of publication and the time from the trial start date or completion date to publication. We also extracted data from the clinical trials included in the research reports, including country of the study's first author, area of health care, means by which the publication status of these trials were sought and the risk of bias in the trials.

Main results: A total of 204 research reports tracking 165,135 trials met the inclusion criteria. Just over half (53%) of these trials were published in full. The median time to publication was approximately 4.8 years from the enrolment of the first trial participant and 2.1 years from the trial completion date. Trials with positive results (i.e. statistically significant results favouring the experimental arm) were more likely to be published than those with negative or null results (OR 2.69, 95% CI 2.02 to 3.60; 19 studies), and they were published in a shorter time (adjusted HR 1.92, 95% CI 1.51 to 2.45; 4 studies). On average, trials with positive results took 2 years to publish, whereas trials with negative or null results took 2.6 years. Large trials were more likely to be published than smaller ones (adjusted OR 1.92, 95% CI 1.33 to 2.77; 11 studies), and they were published in a shorter time (adjusted HR 1.41, 95% CI 1.18 to 1.68; 7 studies). Multicentre trials were more likely to be published than single-centre trials (adjusted OR 1.20, 95% CI 1.03 to 1.40; 2 studies). We found no difference between multicentre and single-centre trials in time to publication. Trials funded by non-industry sources (e.g.governments or universities) were more likely to be published than trials funded by industry (e.g. pharmaceutical companies or for-profit organisations) (adjusted OR 2.13, 95% CI 1.82 to 2.49; 14 studies); they were also published in a shorter time (adjusted HR 1.46, 95% CI 1.15 to 1.86; 7 studies).

Authors' conclusions: Our updated review shows that trial publication is poor, with only half of all trials that are conducted being published. Factors that may make publication more likely and lead to faster publication are positive results, large sample size and being funded by non-industry sources. Differences in publication rates result in publication bias and time-lag bias that may influence findings and therefore ultimately affect treatment decisions. Systematic review authors should consider the possibility of time-lag bias when conducting a systematic review, especially when updating their review.

Funding: This Cochrane review had no dedicated funding.

Registration: This review combines and updates two earlier Cochrane reviews. The two protocols and previous versions of the two updated reviews are available via 10.1002/14651858.MR000006 and 10.1002/14651858.MR000006.pub3 and 10.1002/14651858.MR000011 and 10.1002/14651858.MR000011.pub2.

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Conflict of interest statement

  1. MC: no relevant interests; Co‐ordinating Editor of Cochrane Methodology Review Group and other Cochrane editorial roles but was not involved in the editorial process for this update.

  2. SC: none known.

  3. NDV: no relevant interests; author on two studies awaiting classification: DeVito 2021 (sponsored by the Naji Foundation Doctoral Stipend; Laura and John Arnold Foundation), Salholz‐Hillel 2021 (sponsored by the Naji Foundation; BmBf, Germany).

  4. CF: no relevant interests; works as a health professional at Te Toka Tumai, Auckland District Health Board, New Zealand; Editor for Cochrane Gynaecology and Fertility but was not involved in the editorial process for this update.

  5. VJ: no relevant interests; Editor for Cochrane Gynaecology and Fertility but was not involved in the editorial process for this update.; author of two included studies (for which no funding was received): Showell M, Farquhar CM, Greenwood G, Jordan VMB. Is our public research money well spent? Publication of research outputs from Health Research Council of New Zealand‐funded studies: a cross‐sectional study. BMJ Open. 2023;13(5):e072446; Showell M, Buckman S, Berber S, Ata Allah N, Patterson B, Cole S, Farquhar C, Jordan V. Publication bias in trials registered in the Australian New Zealand Clinical Trials Registry: is it a problem? A cross‐sectional study. PLoS One. 2023 Jan;18(1):e0279926.

  6. MS: no relevant interests; Information Specialist for Cochrane Gynaecology and Fertilitybut was not involved in the editorial process for this update; author of two included studies (for which no funding was received): Showell M, Buckman S, Berber S, Ata Allah N, Patterson B, Cole S, Farquhar C, Jordan V. Publication bias in trials registered in the Australian New Zealand Clinical Trials Registry: is it a problem? A cross‐sectional study. PloS One 2023;18(1):e0279926; Showell Marian, Farquhar Cynthia M, Greenwood Grace, Jordan Vanessa MB. Is our public research money well spent? Publication of research outputs from Health Research Council of New Zealand‐funded studies: a cross‐sectional study. BMJ Open 2023;13(5):e072446.

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References

    1. Dwan K, Gamble C, Williamson PR, Kirkham JJ. Systematic review of the empirical evidence of study publication bias and outcome reporting bias - an updated review. PLoS One 2013;8(7):e66844. [DOI: 10.1371/journal.pone.0066844] - DOI - PMC - PubMed
    1. Schmucker C, Schell LK, Portalupi S, Oeller P, Cabrera L, Bassler D, et al. Extent of non-publication in cohorts of studies approved by research ethics committees or included in trial registries. PLoS ONE [Electronic Resource] 2014;9(12):e114023. - PMC - PubMed
    1. Chan AW. Bias, spin, and misreporting: time for full access to trial protocols and results. PLoS Medicine 2008;5(11):e230. - PMC - PubMed
    1. Song F, Eastwood AJ, Gilbody S, Duley L, Sutton AJ. Publication and related biases. Health Technology Assessment 2000;4(10):1-115. - PubMed
    1. Turner EH, Matthews AM, Linardatos E, Tell RA, Rosenthal R. Selective publication of antidepressant trials and its influence on apparent efficacy. New England Journal of Medicine 2008;358(3):252-60. [1533-4406: (Electronic)] - PubMed

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