Clinical trials

Early clinical trials not always reliable, Mayo researchers find

RESEARCH in brief

The Mayo Clinic recently examined more than 900 randomized controlled trials in top medical journals and found that the surprising number of earliest studies presented exaggerated results. This phenomenon is termed the “Proteus effect”. But knowing the answer to a question involves a body of evidence, not a definitive trial. Therefore, early trials should be viewed with caution. The Food and Drug Administration is reviewing the paper’s finding as they often approve a product based on early studies. What the Mayo Clinic found via meta-analyses was that what we see in the first or second study is not as impressive as what we see later when the studies are repeated by other people in different settings with different patients. Although multiple factors have been discussed resulting in Proteus effect such as having more diverse population later in the studies, the Proteus effect is unpredictable. The Mayo Clinic’s finding also adds to growing evidence that casts a skeptical view on early medical research. This is not, however, meant to be anti-innovative; nor should physicians stop prescribing medicine until more studies are conducted. What this suggests is that patients should be informed of this phenomenon before when being offered newly-approved pharmaceuticals or treatments.

Alahdab F, Farah W, Amasri J, et al. “Treatment effect in earlier trials of patients with chronic medical conditions: a metaepidemiologic study”. Mayo Clin Proc. 2018;93(3):278-283.


  • Marina Kwak


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