VALIDITY ASSESSMENT OF A FOOD FREQUENCY QUESTIONNAIRE FOR SCHOOL-AGE-CHILDREN IN NORTHERN ITALY

We designed a food frequency questionnaire [FFQ] for Northern Italian school-children and tested its validity for the assessment of individu al nutrient intake. Eighty-eight healthy children (49 females, 39 male s - age range 9-12) were investigated. The FFQ we designed consists of 116 food items selected for their common use among our target populat ion (food items found to provide up to 90% of the following nutrients: energy, total lipids, saturate [SFA], polyunsaturate [PUFA] and monou nsaturate [MUFA] fatty acids, carbohydrates, proteins, cholesterol, vi tamins A, B1, B2, B6, C, D, E, calcium, iron, soluble and non-soluble fibres). To test the validity of the FFQ we collected data from a seve n-day dietary record for comparison at the beginning of the study and six months later. The FFQ was distributed to parents several days befo re the collection of the second diary. The validity of the FFQ in the categorizing of individual children at the extreme quintiles was evalu ated with contingency tables; the validity of the individual evaluatio ns of nutrient intake was assessed by Pearson's correlation coefficien t, The estimated energy intake is greater with the use of the FFQ. The intake of most nutrients is comparable, but there is a significant di fference for proteins, PUFA, MUFA, cholesterol, vitamins Fl, C, B6, E and for fibres. The greatest difference was found for vitamins B1 and C. The degree of correlation for most nutrients was within the 0.30 an d 0.58 range. For most nutrients, the calculation of the nutrient dens ity increased the correlation coefficient, while proteins, carbohydrat es and MUFA decreased it. For some nutrients (vitamins A and B6) the c oefficient of correlation was found to be low. The contingency analysi s of absolute nutrient intake shows gross misclassification above all for MUFA and vitamin B1. The use of nutrient density removes the miscl assification for MUFA but not for vitamin B1. Proteins are classified with less consistency when expressed as nutrient density. The comparis on between a standard measurement methodology and the FFQ yields a hig her consistency for individual estimates than for other paediatric pop ulations but lower than that reported in adult populations.