The objective of this study was to perform cross-cultural adaptation of the Mediterranean Islands Study Food Frequency Questionnaire (MEDIS-FFQ) and to evaluate its reproducibility and validity in a population over 60 years of age in the Spanish Mediterranean. Three hundred forty-one people completed the food frequency questionnaire (FFQ), which was administered twice (FFQ1 and FFQ2) with nine 24-h dietary recalls (24-HDRs) over a nine-month period to assess its reproducibility and validity. Cross-cultural translation and adaptation were performed according to the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) guidelines and included direct translation, back-translation, and a pilot comprehension test. Reproducibility was evaluated with Pearson's and interclass correlation coefficients. Validity was estimated using correlations between the FFQ food groups and the 24-HDR mean. The levels of agreement and misclassification were expressed as the proportions of individuals classified by comparing the estimated information from the FFQ2 and the 24-HDR. Reproducibility correlation coefficients ranged from r = 0.44 to r = 0.90. Validity indices ranged from 0.71 to 0.99. More than 80% of the subjects were classified in the same quartile on both instruments. The kappa statistic showed a moderate to high level of agreement (0.70⁻0.95) between the two instruments. In conclusion, the MEDIS-FFQ showed good reproducibility and validity in estimating the nutrient intake of the elderly population in the Spanish Mediterranean.
Keywords: FFQ; elderly; nutrition; reproducibility; validity.