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Comment & Response
December 4, 2018

Protocol Deviations, Reanalyses, and Corrections to PREDIMED Trial Derivative Study on Peripheral Artery Disease

Author Affiliations
  • 1Department of Preventive Medicine and Public Health, Facultad de Medicina–Clínica Universidad de Navarra, Pamplona, Spain
JAMA. 2018;320(21):2272. doi:10.1001/jama.2018.16553

To the Editor As reported elsewhere,1 my coinvestigators and coauthors of the PREDIMED trial have identified protocol deviations, including enrollment of household members without randomization, assignment to a study group without randomization of some participants at 1 of 11 study sites, and apparent inconsistent use of randomization tables at another site. Briefly, in the overall trial,1 425 members of the same household as a previous study participant were directly allocated during the trial to the same group as their previously randomized relative. In addition, 441 individual participants and 26 participant members of the same household who attended small clinics in 1 of the 11 recruiting sites were not individually randomized, but rather were assigned to an intervention group based on clinic (ie, all participants in a particular clinic, the site where the intervention was delivered for small groups of participants, received the same intervention). The original PREDIMED trial compared cardiovascular outcomes from 3 diet groups: (1) a traditional Mediterranean diet plus virgin olive oil, (2) a traditional Mediterranean diet plus nuts, and (3) a low-fat control diet. Derivative studies assessed other outcomes, including peripheral artery disease.