Schröder H, Salas-Salvadó J, Martínez-González MA, Fíto M, Corella D, Estruch R, Ros E. Baseline Adherence to the Mediterranean Diet and Major Cardiovascular Events: Prevención con Dieta Mediterránea Trial. JAMA Intern Med. 2014;174(10):1690-1692. doi:10.1001/jamainternmed.2014.3463
Lifestyle modification, particularly dietary changes, is the cornerstone of population-based strategies for cardiovascular disease (CVD) prevention.1 Recently the Prevención con Dieta Mediterránea (PREDIMED) study,2 a 5-year randomized primary prevention trial (isrctn.org Identifier: ISRCTN35739639), showed a 30% reduction in incident CVD with Mediterranean diet (MeDiet) intervention in comparison with a control diet. At quarterly visits throughout the study, a validated 14-item MeDiet screening tool (Table 1) was used to assess conformity with this dietary pattern.3
Close monitoring of adherence to dietary instructions for CVD prevention is difficult in the clinical setting. Short dietary assessment tools, such as the PREDIMED screener, are desirable to identify individuals in need of dietary counseling. Given that there is little information on the association of diet scores with disease outcomes in longitudinal studies, we investigated whether the baseline 14-point MeDiet score was related to incident CVD in the PREDIMED cohort.
The PREDIMED study is a large randomized trial testing the effect of 2 MeDiets (supplemented with either extra-virgin olive oil or nuts) compared with a control diet (advice on a low-fat diet) on incident CVD in individuals at high risk for but no CVD diagnosed at enrollment. The trial’s design, objectives, and methods have been described.2 Participants included 7447 men and women (mean age, 67 years) with either diabetes mellitus or 3 or more cardiovascular risk factors. The primary end point was an aggregate of myocardial infarction, stroke, or cardiovascular death. This study was approved by the institutional review board of Hospital Clinic, Barcelona, Spain. Written informed consent was obtained from all participants.
General linear modeling procedures were used to compare baseline characteristics of participants by score categories of the 14-point MeDiet screener. Multiple-adjusted Cox proportional hazards regression models were fitted to assess the association between the MeDiet score (or each component) and the major end point. We also generated a weighted MeDiet score to determine whether weighting each score’s item modified the magnitude of the hazard ratios for the association with the outcome.
During a median follow-up of 4.8 years totaling 31 979 person-years, 288 participants sustained CVD events (139 strokes, 106 myocardial infarctions, and 87 cardiovascular deaths). A 2-point increase in unweighted and weighted scores was associated with 21% and 25% reductions in CVD events, respectively, in fully adjusted models (Table 2). Associations between MeDiet scores and CVD were weaker in women and in the control group, but were strengthened by using weighted scores. The proportional hazards assumption was tested (unweighted P > .99; weighted P = .74). Among individual score components, only increased consumption of vegetables and nuts were related to reduced CVD events (Table 1).
As assessed by a short 14-item screener, baseline adherence to the MeDiet in the PREDIMED trial showed an inverse association with incident CVD, independent of lifestyle and classical risk factors. Our findings further document the beneficial effect of the MeDiet on CVD in the PREDIMED trial2 and support the 14-item MeDiet screener as a useful tool to identify individuals needing dietary counseling. It is not surprising that the overall score showed an inverse association with CVD and that most individual score components did not show an inverse association. The combination of foods in an overall healthy dietary pattern is likely to provide stronger protection because this approach captures potential interactions and synergies between different foods and nutrients, reflecting the effect of the whole diet.4 In the present study, a 2-point increase in the 14-point MeDiet score was associated with a 21% reduction in CVD risk. Weighting the strength of each score component increased the magnitude of the association. The extent of the MeDiet’s protective effect estimated by the screener was similar or greater than that reported for MeDiet scores derived from complex, time-consuming food frequency questionnaires.5,6 This screener is thus a useful, simple tool to identify and educate individuals who would benefit most from dietary intervention to reduce future CVD risk.
Corresponding Author: Helmut Schröder, PhD, Cardiovascular Risk and Nutrition Research Group, Hospital del Mar Medical Research Institute, Biomedical Research Park, c/Doctor Aiguader 88, 08003 Barcelona, Spain (email@example.com).
Published Online: August 11, 2014. doi:10.1001/jamainternmed.2014.3463.
Author Contributions: Dr Schröder had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: All authors.
Acquisition, analysis, or interpretation of data: Schröder, Salas-Salvadó, Martínez-González, Fíto, Corella, Estruch.
Drafting of the manuscript: Schröder, Martínez-González, Fíto.
Critical revision of the manuscript for important intellectual content: Salas-Salvadó, Martínez-González, Fíto, Corella, Estruch, Ros.
Statistical analysis: Schröder, Martínez-González.
Obtained funding: Salas-Salvadó, Martínez-González, Corella, Estruch, Ros.
Administrative, technical, or material support: Salas-Salvadó, Martínez-González, Fíto, Corella, Estruch.
Study supervision: Schröder, Salas-Salvadó, Martínez-González, Corella, Estruch.
Conflict of Interest Disclosures: Dr Salas-Salvadó serves on the board of and receives grant support through his institution from the International Nut and Dried Fruit Council, receives consulting fees from Danone, and receives grant support through his institution from Eroski and Nestlé. Dr Estruch serves on the board of and receives lecture fees from the Research Foundation on Wine and Nutrition, serves on the boards of the Beer and Health Foundation and the European Foundation for Alcohol Research, receives lecture fees from Cerveceros de España and sanofi-aventis, and receives grant support through his institution from Novartis. Dr Ros serves on the board of and receives travel support, as well as grant support through his institution, from the California Walnut Commission; serves on the board of the Flora Foundation (Unilever); serves on the board of and receives lecture fees from Roche; serves on the board of and receives grant support through his institution from Amgen; receives consulting fees from Damm and Abbott Laboratories; receives consulting fees and lecture fees, as well as grant support through his institution, from Merck; receives lecture fees from Aegerion, AstraZeneca, Danone, Pace, and Rottapharm; receives lecture fees and payment for the development of educational presentations, as well as grant support through his institution, from Ferrer; receives payment for the development of educational presentations from Recordati; and receives grant support through his institution from Daiichi Sankyo, Feiraco, Karo Bio, Nutrexpa, Pfizer, sanofi-aventis, Synageva, Takeda, and Unilever.
Funding/Support: The PREDIMED trial was supported by the official funding agency for Biomedical Research of the Spanish Government, Instituto de Salud Carlos III, through grants provided to research networks specifically developed for the trial: RTIC G03/140 (coordinator: R. Estruch, MD, PhD), CIBERobn (coordinator: F. Casanueva, MD, PhD), and RTIC RD 06/0045 (coordinator: M.A. Martínez-González, MD, PhD). We also acknowledge grants from Centro Nacional de Investigaciones Cardiovasculares CNIC 06/2007, Fondo de Investigación Sanitaria–Fondo Europeo de Desarrollo Regional (PI04-2239, PI 05/2584, CP06/00100, PI07/0240, PI07/1138, PI07/0954, PI 07/0473, PI10/01407, PI11/01647), Ministerio de Ciencia e Innovación (AGL-2009-13906-C02, AGL2010-22319-C03), Fundación Mapfre 2010, Public Health Division of the Department of Health of the Autonomous Government of Catalonia and Generalitat Valenciana (ACOMP06109, GVACOMP2010-181, GVACOMP2011-151, CS2010-AP-111, and CS2011-AP-042), and a joint contract (CES09/030) with the Instituto de Salud Carlos III and the Health Department of the Catalan Government (Generalitat de Catalunya).
Role of the Sponsor: The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Trial Registration: isrctn.org Identifier: ISRCTN35739639
Additional Information: The supplemental foods used in PREDIMED study were generously donated by Patrimonio Comunal Olivarero and Hojiblanca from Spain (extra-virgin olive oil), the California Walnut Commission from Sacramento, CA (walnuts), and Borges S.A. (almonds) and La Morella Nuts (hazelnuts), both from Reus, Spain. CIBERobn and RTIC RD 06/0045 are initiatives of Instituto de Salud Carlos III, Spain.