Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
Centre for Public Health, Queen's University Belfast, Belfast, UK.
Cochrane Database Syst Rev. 2024 Nov 27;11(11):MR000011. doi: 10.1002/14651858.MR000011.pub3.
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.
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.
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.
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.
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.
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.
This Cochrane review had no dedicated funding.
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.
进行试验的研究人员有责任在同行评议期刊上发表其工作结果，如果未能做到这一点，可能会引入影响现有证据准确性的偏倚。此外，未能发表研究结果会造成研究浪费。
系统综述从临床试验开始就对其进行跟踪的研究报告及其调查的发表率和发表时间。我们还旨在评估某些因素是否会影响发表和发表时间。
我们从临床试验开始到 2023 年 8 月 23 日，通过搜索 MEDLINE、Embase、Epistemonikos、Cochrane 方法学注册库（CMR）和美国医疗保健研究与质量局（AHRQ）数据库，确定了研究。我们还检查了相关研究的参考文献，并联系了该领域的专家以获取任何其他研究。
如果研究报告跟踪了一组临床试验，并对这些试验的发表率或发表时间的任何方面进行了分析，则符合纳入标准。
两名综述作者独立进行数据提取。我们从研究报告中包含的临床试验中提取了关于发表率和从试验开始日期或完成日期到发表日期的时间的数据。我们还从研究报告中包含的临床试验中提取了数据，包括第一作者所在国家/地区的卫生保健领域、寻找这些试验发表情况的手段以及试验的偏倚风险。
共有 204 项研究报告跟踪了 165135 项试验，符合纳入标准。这些试验中只有略多于一半（53%）发表了全文。从第一个试验参与者入组到发表的中位时间约为 4.8 年，从试验完成日期到发表的中位时间为 2.1 年。阳性结果（即支持试验组的统计学显著结果）的试验比阴性或无效结果的试验更有可能发表（OR 2.69，95%CI 2.02 至 3.60；19 项研究），且发表时间更短（调整后的 HR 1.92，95%CI 1.51 至 2.45；4 项研究）。平均而言，阳性结果的试验需要 2 年才能发表，而阴性或无效结果的试验则需要 2.6 年。大型试验比小型试验更有可能发表（调整后的 OR 1.92，95%CI 1.33 至 2.77；11 项研究），且发表时间更短（调整后的 HR 1.41，95%CI 1.18 至 1.68；7 项研究）。多中心试验比单中心试验更有可能发表（调整后的 OR 1.20，95%CI 1.03 至 1.40；2 项研究）。我们没有发现多中心试验和单中心试验在发表时间上的差异。非工业来源（如政府或大学）资助的试验比工业来源（如制药公司或营利性组织）资助的试验更有可能发表（调整后的 OR 2.13，95%CI 1.82 至 2.49；14 项研究）；发表时间也更短（调整后的 HR 1.46，95%CI 1.15 至 1.86；7 项研究）。
我们的更新综述表明，试验发表情况不佳，只有一半以上的已进行试验发表。可能使发表更有可能并导致更快发表的因素是阳性结果、样本量大以及由非工业来源资助。发表率的差异会导致发表偏倚和时间滞后偏倚，从而可能影响发现，并最终影响治疗决策。进行系统综述的系统综述作者应考虑时间滞后偏倚的可能性，尤其是在更新综述时。
本 Cochrane 综述没有专门的资金。
本综述结合并更新了两项先前的 Cochrane 综述。这两项方案和之前的两个更新版本的两个协议可通过 10.1002/14651858.MR000006 和 10.1002/14651858.MR000006.pub3 和 10.1002/14651858.MR000011 和 10.1002/14651858.MR000011.pub2 获得。
