Relative validity and reliability of a quantitative food frequency questionnaire for adults in Guam
Sammanfattning
Background: Guam is a US territory in the western Pacific with a diverse population that includes
understudied ethnic groups such as Chamorros and Filipinos. A food frequency questionnaire (FFQ)
to
estimate dietary intake was needed to facilitate studies of diet and health among adults living in
Guam.
Objective: To develop and validate an FFQ to assess dietary intake over a 1-year period among adult
Guam
residents.
Design: A three-part study was conducted: 1) an initial cross-sectional study using 24-h recalls to
identify
a food and beverage list for the FFQ and resulting in a final FFQ containing 142 food and drink items;
2) to test reliability, 56 different individuals completed the FFQ twice; and 3) to test relative validity,
selfadministered
FFQs and up to 2 days of food record data from an additional 109 individuals were collected,
and daily nutrient intake from the two methods was compared.
Results: The reliability of the FFQ was very good (p range0.650.75), and the relative validity of the
FFQ was good for women (median Spearman’s correlation [p] between instruments of 0.45 across 20
nutrients and an interquartile range [IQR] of 0.42-0.58) and generally adequate for men (median p
=0.31,
IQR0.230.55). Validity was also good for Chamorros (median p =0.47, IQR0.380.53) and
generally
adequate for Filipinos (median p =0.42, IQR=0.20-0.62). Correlations after energy adjustment were
lower
(overall median p =0.20, IQR=0.140.26).
Conclusions: The FFQ can be used to rank nutrient intake for adults in Guam and may be helpful in
the
analysis of relationships between diet and chronic disease in Guam.