Validation of a semi-quantitative FFQ using food records as a reference in older women in the Kuopio Fracture Prevention Study (OSTPRE-FPS)

Objective: To validate an eighty-nine-item semi-quantitative FFQ for measurement of nutrient intakes in elderly women. Design: FFQ and 3 d food records were filled in by women participating in the Kuopio Fracture Prevention Study (OSTPRE-FPS). Data on intakes of energy, fat, protein, carbohydrate, fibre, Ca, Fe, P, K, Mg, folic acid, vitamin B-12(,) vitamin C, vitamin D and vitamin K from ninety-nine women were available to assess the agreement of the two methods. Validity was assessed using correlation coefficients, cross-classification into quintile categories and Bland-Altman plots. Nutrients relevant to bone health were assessed. Setting: OSTPRE-FPS in Finland. Subjects: Elderly women with a mean age 71.3 years. Results: The FFQ overestimated energy and nutrient intakes as compared with food records by 30-50 %. The highest correlation coefficients of the energy-adjusted nutrient intakes between the methods were observed for fibre (0.60), Mg (0.56) and folic acid (0.49) and the lowest for protein and vitamin D (both 0.19). The cross-classification of energy-adjusted nutrient intakes showed that on average 68% of the participants (range 62-78 %) were classified into the same or an adjacent quintile category. Conclusions: The validity of energy and nutrient intakes measured with the FFQ was moderate as compared with 3 d food records in elderly women. The FFQ is a useful tool for the nutrient assessment of elderly women in epidemiological research.