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Most Covid clinical trials are slow to make results public – new study

Only 19% of completed clinical trials of Covid-19 treatments and vaccines have made their results public within three months of trial completion, a new analysis shows. In addition, data on trial registries is often not being kept up to date.

In November 2020, the US National Institutes of Health called for the rapid publication of Covid trial results on, the world’s largest registry. In January 2021, experts pointed out that the US government can require trial results to be reported within just 30 days if it is “necessary to protect the public health,” but to date the government had not made use of those powers.

Using trial registry data, the study team identified 285 interventional trials that had been completed by the end of June 2020, and then searched academic journals, preprint servers and trial registries to check whether results had been made public.

The vast majority of available results had been published as preprints and journal articles. Only two results of Covid trials had been uploaded directly onto trial registries.

The study notes that some researchers are failing to keep trial registry data up to date, or not following best practices in results reporting, making it difficult to gain a comprehensive overview of global research efforts and their findings.

The study’s authors concluded that:

“Many of the trials registered, and apparently completed, during the first six months of the pandemic failed to yield rapid results in the literature or on clinical trial registries. Nevertheless, our findings suggest that the COVID-19 response may be seeing quicker results disclosure in general compared to non-emergency conditions.”

“Maintaining accuracy in clinical trial registrations should be a priority, especially during global public health emergencies, when collaboration and research prioritisation is key to the efficient advancement of knowledge.”

“The stakes of a global pandemic only amplify the importance of minimizing reporting issues that may impact evidence synthesis, guideline development, and ultimately clinical practice. Failure to update registry entries compromises an important tool for transparency and accountability in the COVID-19 research response. Crucial efforts to collect and examine the evidence around COVID-19 may be slowed by searching for or anticipating results that may simply never come and/or should not be expected.”

Commenting on the findings, Till Bruckner, founder of TranspariMED, said:

“The treatment of Covid patients can only improve as rapidly as research results are made public. This study is important because it shows that even in a global public health emergency, it can still take a long time until the results of clinical trials are made public."

"It is especially disappointing that trial registries are not being used more widely as a platform for rapid results sharing. Going forward, we need a discussion in the medical research community on how the publication of trial results – and not just for Covid trials – can be accelerated without compromising quality.”

Some – but not all – Covid trials are already subject to European Union or U.S. disclosure rules, but these only require results to be made public on trial registries within 12 months of trial completion. WHO best practices set the same timeframe.

The study team used a comprehensive search strategy, but did not include results published in the grey literature such as press releases or conference abstracts in its analysis. The same team is currently working on a follow-up study that will cover all Covid trials completed during 2020. TranspariMED was not involved in the design or implementation of the study.

Comprehensive lists of on all ongoing and completed Covid clinical trials can be found on the Covid-19 TrialsTracker and the Covid-evidence database.


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