Relative validity of a semi-quantitative food-frequency questionnaire in an elderly Mediterranean population of Spain

The aim of the present study was to assess reproducibility and relative validity of a self-administered FFQ used in the PREDIMED Study, a clinical trial for primary prevention of CVD by Mediterranean diet in a population at high cardiovascular risk. The FFQ was administered twice (FFQ1 and FFQ2) to explore reproducibility at 1 year. Four 3 d dietary records (DR) were used as reference to explore validity; participants therefore recorded their food intake over 12 d in the course of 1 year. The degree of misclassification in the FFQ was also evaluated by a contingency table of quintiles comparing the information from the FFQ2 and the DR. A total of 158 men and women (aged 55– 80 years) were a…