The Prevención con Dieta Mediterránea (PREDIMED) was a multicenter, randomized, primary prevention feeding trial with blinded assessment of end points conducted in Spain between October 2003 and December 2010.
Eligible participants were men aged 55 to 80 years and women aged 60 to 80 years without clinical PAD or baseline cardiovascular disease but with type 2 diabetes mellitus or at least 3 cardiovascular risk factors.
Participants were randomized in a 1:1:1 ratio to 1 of 3 groups: a Mediterranean diet supplemented with extra-virgin olive oil; a Mediterranean diet supplemented with nuts; or counseling on a low-fat diet (control group). All participants received a comprehensive dietary educational program on a quarterly basis. The intensity of the program delivered to the control group was increased in October 2006.
The protocol was approved by institutional review boards and written informed consent was obtained from all participants.
New symptomatic PAD events were confirmed by a central end-point adjudication committee that was blinded to the allocated group. A confirmed diagnosis of PAD in symptomatic patients required at least 1 of the following criteria: an ankle-brachial index of less than 0.9 at rest, a clinical diagnosis of arterial occlusive disease based on imaging tests (duplex ultrasonography, magnetic resonance angiography, computed tomographic angiography, or catheter-based radiocontrast angiography), or an endovascular or open surgical procedure (revascularization or amputation).
We used Stata version 12.1 (StataCorp) for statistical analyses. Kaplan-Meier curves and Cox proportional hazards models adjusted for baseline factors were used to compare the risk of PAD for each diet group vs the control group on an intention-to-treat basis.
The number needed to treat (NNT) was estimated for each diet group vs control group. As a sensitivity analysis, we used multiple imputation algorithms for participants without any events or study contact for at least 2 years.