Publication bias in trials registered in the Australian New Zealand Clinical Trials Registry: Is it a problem? A cross-sectional study

Reporting summary results in clinical trial registries: updated guidance from WHO

The importance of publicly registering clinical trials and reporting their results in registries is widely recognised. While substantial progress has been made with registering trials before enrolment, the availability of results in registries remains uncommon despite expanding legislative and funder requirements-leading to an incomplete evidence base and avoidable waste of resources, particularly for unpublished trials. This paper discusses the rationale for reporting summary results in trial registries, reviews the current landscape of registry policies, and presents new WHO guidance for reporting results in registries. The 2025 WHO guidance was developed after consultation with relevant parties, including researchers, patients, sponsors, funders, regulators, journal editors, registry administrators, and the public. The guidance defines eight minimum items that are essential for understanding and interpreting the summary results for all trials. Implementation of the WHO guidance by trial registries, broad adherence by investigators and sponsors, and endorsement by funders, regulators, legislators, research ethics committees, patient organisations, and journals can help enhance the contribution of trials to scientific knowledge, patient care, and health policy.

Characteristics of exercise and rehabilitation intervention clinical trials registered with Clinical Research Information Service: a review

Exercise and rehabilitation interventions are essential for health restoration, yet reviews on related clinical trials remain limited despite increasing research interest. This study analyzed the characteristics, designs, sample sizes, and outcome variables of clinical trials registered with the Clinical Research Information Service in South Korea, focusing on exercise and rehabilitation interventions. A systematic search using "exercise" and "rehabilitation" identified 1,089 trials registered up to June 9, 2024, with 470 meeting the inclusion criteria. Most studies (79.79%) were retrospectively registered, and 45.11% were open-label trials. Behavioral interventions (26.60%) and medical devices (22.34%) were most common, targeting circulatory (27.45%) and musculoskeletal (19.79%) conditions. Frequently assessed outcomes included 'balance,' 'pain,' and 'walking.' A notable increase in trials was observed since 2017. However, the high proportion of retrospective registrations and open-label designs highlights the need for more prospective and blinded trials to enhance research quality.

Poor registration and publication practices in clinical trials of targeted therapeutics for endocrine and metabolic diseases: an observational study

OBJECTIVES

To assess the completeness and concordance of reporting in registries and corresponding publications of interventional trials on targeted therapeutics for endocrine and metabolic disorders.

STUDY DESIGN AND SETTING

We searched clinical trial registries in September 2022 for completed interventional trials of target therapeutics for endocrine and metabolic disorders registered from 2005 onwards. We used ClinicalTrials.gov and the World Health Organization International Clinical Trial Registration Platform registration requirements to extract data and assess the completeness of initial entry and final updates to trial registration and concordance with their published journal articles.

RESULTS

Among 149 clinical trials included, 121 (81%) had corresponding publications. Missing mandatory registration data items were identified in 89 (67%) trials at the initial registration entry, 17 (13%) at the final registration update, and in 85 (77%) corresponding publications. All trials showed changes between initial registration entry and final registration update, and 98% showed changes from the initial registration entry to publication. Changes between initial registration entry and final registration update were most common in the categories 'Completion date' (92%), 'Key secondary outcomes' (82%), and 'Date of first enrolment' (70%). Changes between initial registration entry and publication were most common in categories 'Sample size' (91%), 'Key inclusion and exclusion criteria' (81%), 'Key secondary outcomes' (84%), and 'Completion date' (83%).

CONCLUSION

Despite the legal and journal registration requirements, the completeness and consistency of reporting mandatory data items in registries and corresponding publications regarding targeted therapeutics for endocrine and metabolic disorders are inadequate. Our findings raise questions about the integrity and reliability of clinical trials focusing on targeted therapeutics.

PLAIN LANGUAGE SUMMARY

This study evaluated the completeness of reporting of mandatory information about clinical trials of targeted therapies for endocrine and metabolic diseases in trial registries and published articles. Furthermore, we examined whether the information in trial registries aligns with what is reported in scientific journals. Our analysis focused on completed interventional trials registered from 2005 onwards using trial registries. We found that 67% of the included trials were missing mandatory information at the time of initial entry into registry, while 77% of the matching publications also lacked mandatory information. The most common discrepancies between the entry into registry and published data occurred in the mandatory categories of sample sizes and key inclusion and exclusion criteria for participants. Our findings highlight major gaps in how clinical trials for targeted therapies in endocrine and metabolic diseases are conducted. Despite established requirements for accurate registration and publication of mandatory trial information, substantial discrepancies persist between the data in registries and published results. These inconsistencies raise concerns about the reliability of reported findings and underscore the urgent need for improved practices in trial registration and reporting.

Time to publication for results of clinical trials

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.

Supporting study registration to reduce research waste

An estimated 82-89% of ecological research and 85% of medical research has limited or no value to the end user because of various inefficiencies. We argue that registration and registered reports can enhance the quality and impact of ecological research. Drawing on evidence from other fields, chiefly medicine, we support our claim that registration can reduce research waste. However, increasing registration rates, quality and impact will be very slow without coordinated effort of funders, publishers and research institutions. We therefore call on them to facilitate the adoption of registration by providing adequate support. We outline several aspects to be considered when designing a registration system that would best serve the field of ecology. To further inform the development of such a system, we call for more research to identify the causes of low registration rates in ecology. We suggest short- and long-term actions to bolster registration and reduce research waste.

Depression clinical trials worldwide: a systematic analysis of the ICTRP and comparison with ClinicalTrials.gov

Major depressive disorder (MDD), commonly known as depression, affects over 300 million people worldwide as of 2018 and presents a wide range of clinical symptoms. The international clinical trials registry platform (ICTRP) introduced by WHO includes aggregated data from ClinicalTrials.gov and 17 other national registers, making it the largest clinical trial platform. Here we analysed data in ICTRP with the aim of providing comprehensive insights into clinical trials on depression. Applying a novel hidden duplicate identification method, 10,606 depression trials were identified in ICTRP, with ANZCTR being the largest non- ClinicalTrials.gov database at 1031 trials, followed by IRCT with 576 trials, ISRCTN with 501 trials, CHiCTR with 489 trials, and EUCTR with 351 trials. The top four most studied drugs, ketamine, sertraline, duloxetine, and fluoxetine, were consistent in both groups, but ClinicalTrials.gov had more trials for each drug compared to the non-ClinicalTrials.gov group. Out of 9229 interventional trials, 663 unique agents were identified, including approved drugs (74.5%), investigational drugs (23.2%), withdrawn drugs (1.8%), nutraceuticals (0.3%), and illicit substances (0.2%). Both ClinicalTrials.gov and non-ClinicalTrials.gov databases revealed that the largest categories were antidepressive agents (1172 in ClinicalTrials.gov and 659 in non-ClinicalTrials.gov) and nutrients, amino acids, and chemical elements (250 in ClinicalTrials.gov and 659 in non-ClinicalTrials.gov), indicating a focus on alternative treatments involving dietary supplements and nutrients. Additionally, 26 investigational antidepressive agents targeting 16 different drug targets were identified, with buprenorphine (opioid agonist), saredutant (NK2 antagonist), and seltorexant (OX2 antagonist) being the most frequently studied. This analysis addresses 40 approved drugs for depression treatment including new drug classes like GABA modulators and NMDA antagonists that are offering new prospects for treating MDD, including drug-resistant depression and postpartum depression subtypes.

Implementation Documentation and Process Assessment of the PharmNet Intervention: Observational Report

BACKGROUND

The number of overdose deaths in the United States involving opioids continues to exceed 100,000 per year. This has precipitated ongoing declarations of a public health emergency. Harm reduction approaches, such as promoting awareness of, ensuring access to, and fostering willingness to use naloxone to reverse opioid overdose, are a key component of a larger national strategy to address the crisis. In addition, overdose reversal with naloxone directly and immediately saves lives. Because of pharmacies' ubiquity and pharmacists' extensive clinical training, community pharmacies are well-positioned, in principle, to facilitate naloxone access and education.

OBJECTIVE

In 2022, a single-site pilot study of PharmNet, a community pharmacy intervention incorporating naloxone distribution, awareness building, and referral, showed promising outcomes for both naloxone and resource distribution in the community. As a next step, this study was intended to be a pilot randomized controlled trial of PharmNet in 7 pharmacies. However, due to circumstances outside of the study team's control, data collection was unable to be fully completed as planned. In keeping with open research standards, we transparently report all available data from the study and discuss trial barriers and processes. We do so both to provide insights that may inform similar studies and to avoid the "file-drawer" (publication bias) problem, which can skew the aggregated scholarly literature through nonpublication of registered trial results or selective publication of findings affirming authors' hypotheses.

METHODS

This paper reports an in-depth implementation study assessment, provides the available observational data, and discusses implementation considerations for similar studies in independent (eg, nonchain) community pharmacies.

RESULTS

Retrospective assessment of study outcomes and fidelity data provided for robust discussion around how resource differences in independent community pharmacies (vs well-resourced chain pharmacies), as well as high demands on staff, can affect intervention implementation, even when leadership is highly supportive.

CONCLUSIONS

Community pharmacies, particularly independent community pharmacies, may require more support than anticipated to be successful when implementing a new intervention into practice, even if it might affect estimates of real-world effectiveness. Further implementation science research is needed specific to independent community pharmacies. All study elements are outlined in the International Registered Report Identifier (IRRID) PRR1-10.2196/42373. Although this paper reports results associated with that registration, results and conclusions should not be given the weight assigned to findings from a preregistered study.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR2-10.2196/42373.