Reproducibility and Validity of an Expanded Self-Administered Semiquantitative Food Frequency Questionnaire among Male Health Professionals

TLDR

The study evaluated the reproducibility and validity of a 131‑item semiquantitative food frequency questionnaire in a cohort of 51,529 male health professionals. Participants received the questionnaire by mail twice, one year apart, and completed two one‑week diet records spaced roughly six months apart. Intake estimates from the questionnaire were highly correlated with diet records (r = 0.28–0.86, mean = 0.59, rising to 0.65 after adjusting for week‑to‑week variation) and intraclass correlations ranged from 0.47 to 0.80, demonstrating reproducibility and usefulness for many nutrients over a year. Am J Epidemiol 1992; 135: 1114–26.

Abstract

The authors assessed the reproducibility and validity of an expanded 131-item semiquantitative food frequency questionnaire used in a prospective study among 51, 529 men. The form was administered by mail twice to a sample of 127 participants at a one-year interval. During this interval, men completed two one-week diet records spaced approximately 6 months apart. Mean values for intake of most nutrients assessed by the two methods were similar. Intraclass correlation coefficients for nutrient intakes assessed by questionnaires one year apart ranged from 0.47 for vitamin E without supplements to 0.80 for vitamin C with supplements. Correlation coefficients between the energy-adjusted nutrient intakes measured by diet records and the second questionnaire (which asked about diet during the year encompassing the diet records) ranged from 0.28 for iron without supplements to 0.86 for vitamin C with supplements (mean r = 0.59). These correlations were higher after adjusting for week-to-week variation in diet record intakes (mean r = 0.65). These data indicate that the expanded semiquantitative food frequency questionnaire is reproducible and provides a useful measure of intake for many nutrients over a one-year period. Am J Epidemiol 1992; 135: 1114–26