Effect of using repeated measurements of a Mediterranean style diet on the strength of the association with cardiovascular disease during 12 years: The Doetinchem Cohort Study

Background: In cohort studies, often only one baseline measurement of dietary intake is available. This may underestimate the strength of the association with cardiovascular diseases (CVD). Objective: The main objective is to compare the strength of the association of a Mediterranean style diet with CVD using one baseline measurement of diet versus three repeated measurements over a 10-year period. Design: We used dietary and lifestyle data of three rounds of the Doetinchem Cohort Study. At baseline, 7,769 persons aged 20-65 years were examined. Diet was assessed with a 178 item validated food-frequency questionnaire and operationalized with the Mediterranean Diet Score (MDS) ranging from 0 to 9. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95 % confidence intervals (CI). Analyses were adjusted for age, sex, and repeated measurements of smoking, sports, total energy intake, and educational level. Results: Comparing an MDS of ≥5.5-9 to an MDS of 0-<3.5, baseline MDS was associated with a 23 % lower risk [HR 0.77 (95 % CI 0.53-1.11)] and the updated mean with a 35 % lower risk [HR 0.65 (0.43-0.97)] of a composite of fatal CVD, nonfatal myocardial infarction, and stroke (composite CVD). For fatal CVD, baseline MDS was associated with a 13 % lower risk [HR 0.87 (0.36-2.07)] and the updated mean with a 56 % lower risk [HR 0.44 (0.19-1.05)]. Conclusion: The strength of the association between a Mediterranean style diet and CVD is likely underestimated because most studies so far used only one baseline measurement.