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Public registries curb bias in clinical trials: JAMA study

October 2, 2017

Dr. An-Wen Chan
Dr. An-Wen Chan

Half of clinical trials are never published. Unpublished findings mean that important evidence about the efficacy and safety of treatments are never made available to patients or healthcare providers.

“There should be concern that the evidence policy-makers are relying on is based on a select and biased subset of information,” says Dr. An-Wen Chan, a scientist at Women’s College Research Institute.

Dr. Chan led a new study published in JAMA: The Journal of the American Medical Association that found public registration for clinical trials, using services such as ClinicalTrials.gov, could increase publication rates and reduce bias in reported findings.

The study reviewed clinical trials in Finland and found that registered trials were much more likely to be published than unpublished trials.

Another issue is that scientists can sometimes change the focus of their clinical trial after seeing the data. “After having a look at the results, investigators or sponsors may choose to highlight the more positive results and downplay the negative results,” Dr. Chan says.

The findings showed that registered trials were more likely to report the same primary outcomes as the ones they defined at the outset, rather than selectively reporting some outcomes but not others.

A third of clinical trials were not registered, according to the study, which was the first reliable measure of how many clinical trials are registered. The suboptimal adherence persists despite widespread policies by scientific journals, funders, research ethics boards and other authorities that require registration.

Dr. Chan says the findings highlight many researchers or sponsors are not following existing regulations. “Journal editors, regulators and funders need to implement stronger policies, and better mechanisms to enforce them,” Dr. Chan says.

Dr. Chan presented the findings on Sept. 11 at the Eighth International Congress on Peer Review and Scientific Publication.


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