Comparative Validation of the Block, Willett, & NCI Food Frequency Questionnaires
Summary: The 1997-1998 Eating at
America's Table Study (EATS) validated a new NCI-developed food frequency
questionnaire (FFQ), the Diet History Questionnaire (DHQ),
and compared its performance to that of two other FFQs widely used at the time,
the 1995 Block FFQ and the purple version of the Willett FFQ. The DHQ performed
as well as or better than the other two FFQs. Results from this study also
point the way to future research in exploring the structure of measurement error
in current methods of assessing dietary intake.
Reference: Subar AF, Thompson FE, Kipnis V, Midthune D,
Hurwitz P, McNutt S, McIntosh A, Rosenfeld S. Comparative Validation of the
Block, Willett, and National Cancer Institute Food Frequency Questionnaires.
Am J Epidemiol 2001;154(12):1089-99.
The most practical and economical way to collect comprehensive dietary data
in large epidemiologic studies is the food frequency questionnaire (FFQ). FFQs
are designed to capture individuals' usual dietary intake by asking respondents
to report their frequency of consumption of a list of foods over a specific
period of time. Efforts to improve the accuracy of FFQs are essential to
improving our ability to measure dietary intake patterns and thereby to better
understand of the role of diet in the etiology and prevention of chronic
diseases such as cancer.
The Eating at America's Table Study (EATS) was designed to validate the Diet
History Questionnaire (DHQ), a new and improved FFQ developed by the National
Cancer Institute, and to compare it against two other widely used FFQs -- the
1995 NCI-Block Health Habits and History Questionnaire and the Willett (purple
version) FFQ. Of the 1,640 eligible individuals recruited for the study, 1,301
participants first completed four 24-hour dietary recalls over the course of a
year. Following this phase, participants were randomized into two groups, one
of which completed the DHQ and the Block FFQ. The other group completed the DHQ
and the Willett FFQ. The DHQ was validated by assessing the correlations and
attenuation coefficients between nutrient intakes estimated on the DHQ and
"true" intakes estimated from the four 24-hour recalls using a measurement error
model. The investigators also determined correlations between the Block and
Willet FFQs and these "true" intakes.
Results showed that absolute nutrient intakes for women estimated by the DHQ
and Block FFQs were fairly comparable to the 24-hour recalls; the Willett
instrument tended to overestimate nutrient intake for women. All three
instruments underestimated absolute nutrient intake for men, compared with the
recalls, though the Willett instrument underestimated to a greater degree than
did the other two FFQs. Correlation and attenuation coefficients were somewhat
higher for the DHQ than for the Block FFQ, and both were better than the Willett
FFQ in models unadjusted for energy. Energy adjustment increased correlation
and attenuation coefficients dramatically for the Willett FFQ and modestly for
the other two FFQs, suggesting that energy adjustment, in general, reduces
measurement error in all FFQs. The lack of portion size information in the
Willett FFQ may partially explain the differences in absolute intakes among the
three FFQs.
To better understand the structure of measurement error in FFQs, the authors
urge further research in varied populations with biomarker reference instruments
that are not based on self-report. At the same time, EATS has shown that this
improved, cognitively-based FFQ is as good as or better than two FFQs that were
in wide use at the time and is a reasonable alternative for investigators to use
in a data collection domain that is still primarily dependent on self-reported
information.
Learn more about the Risk Factor Monitoring and Methods
Branch's dietary assessment tools for researchers.
<< Previous Summary |
Next Summary >>
|