Reproducibility and validity of a food-frequency questionnaire in assessing dietary intakes and food habits in epidemiological cancer studies in Argentina

A Food-Frequency questionnaire(FFQ) is the method chosen for estimating die tary intake in epidemiological studies because it can provide valid and rel iable estimates of usual intake in a variety of populations. Colorectal can cer is associated with diet but no information about validity and reproduci bility of dietary exposure assessment is available in Argentina. The purpose of the study is to evaluate the validity and reproducibility of the FFQ used in assessing the relationship between dietary intake and colo rectal cancer. Selected nutrient intake, measured by two interviewer-administered FFQs, wa s compared with average intake derived from using four 24 hour dietary reca lls (DR) as the reference method, for 62 control subjects from Cordoba, Arg entina. Pearson's product-moment and Spearman correlation coefficients were used. Nutrient intakes were adjusted for energy, sex and age using tertile s of residuals from regression models. Weighted and unweighted kappa statis tics were calculated for both FFQs versus DR. The mean correlation coefficients between DR and FFQs were 0.74. Agreement measurement (Kappa) varied from 0.51 to 0.74 for FFQ1 vs. FFQ2 to between 0 .71 and 0.87 for FFQ1 and FFQ2. This study demonstrates an acceptable valid ity and reproducibility for this FFQ. The pattern of the correlation coeffi cients found in the present study indicates that the FFQ can provide an acc eptable assessment of long-term dietary intake in the Argentine population and in other Latin-american areas.