Reproducibility and validity of a quantitative food frequency questionnaire in an urban and rural area of northern India.
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Date
2013-09
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Abstract
Background. Food frequency questionnaires (FFQs) have
been used in epidemiological studies across the world to
capture the usual food intake of individuals. As food habits
vary in different population groups, FFQs should be validated
before use. Hence, we determined the reproducibility and
validity of FFQs designed for urban and rural populations of
northern India.
Methods. Separate FFQs, designed for urban and rural
populations using standard methods, were administered to a
sample of 200 subjects (100 urban and 100 rural) in the age
group of 35–70 years in the beginning (baseline FFQ) of the
study and after an interval of 1 year (1-year FFQ) to assess
their reproducibility. Six 24-hour dietary-recalls, taken at an
interval of 2 months over a period of 1 year, were used as a
reference method to test the validity. Crude and energyadjusted
nutrient intakes estimated from FFQs and 24-hour
dietary-recalls were compared using Pearson correlation
coefficients. Bland and Altman plots were also used to test the
agreement between the two methods.
Results. Nutrient intakes were found to be similar at the
baseline and 1-year FFQs in urban and rural areas. The
unadjusted Pearson correlation between 24-hour dietaryrecalls
and 1-year FFQ ranged from 0.22 for vitamin C to
0.63 for iron in the urban area. It ranged from 0.06 for
vitamin C to 0.74 for energy in the rural area. The correlations
lowered after adjusting for energy and there was a minimal
increase after de-attenuation.
Conclusion. The FFQs were reproducible and valid for
assessing nutrient intakes except for some micronutrients.
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MAHAJAN R, MALIK M, BHARATHI A V, LAKSHMI P V M, PATRO B K, RANA S K, KUMAR R. Reproducibility and validity of a quantitative food frequency questionnaire in an urban and rural area of northern India. National Medical Journal of India. 2013 Sept-Oct ; 26 (5): 266-272.