A drug’s true risk-benefit profile relative to other standard therapies can be skewed by selective reporting of the results of trials, new research has found.
Ida Sim and colleagues from the University of California San Francisco, in the US, researched the publication status of all 909 clinical trials that supported the 90 new drug approvals by the US Food and Drug Administration (FDA) between 1998 and 2000.
They report that a pivotal trial in which a new drug works better than an old drug is more likely to be published than a trial in which the new drug does no better.
This is a form of publication bias that may lead to an inappropriately favourable record in the medical literature of a drug’s true value, and can lead to preferential prescribing of newer and more expensive treatments, they said.
Over half of all supporting trials for FDA-approved drugs remain unpublished five years after approval, says the new research published in this week’s PLoS Medicine.
The most important trials determining efficacy, and those with statistically significant results and larger sample sizes, are more likely to be published.
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