Open Access Research

Assessing the validity of a self-administered food-frequency questionnaire (FFQ) in the adult population of Newfoundland and Labrador, Canada

Lin Liu1, Peizhong Peter Wang123*, Barbara Roebothan1, Ann Ryan4, Christina Sandra Tucker1, Jennifer Colbourne1, Natasha Baker1, Michelle Cotterchio5, Yanqing Yi1 and Guang Sun6

Author Affiliations

1 Division of Community Health and Humanities, Faculty of Medicine, Memorial University, 300 Prince Philip Drive, St. John’s, NL, A1B 3V6, Canada

2 School of Public Health, Tianjin Medical University, Tianjin, China

3 First Affiliated Hospital, Wenzhou Medical College, Wenzhou, China

4 Health Research Unit, Faculty of Medicine, Memorial University, St. John’s, Canada

5 Population Study and Surveillance, Cancer Care Ontario, Toronto, ON, Canada

6 Discipline of Medicine, Faculty of Medicine, Memorial University, St. John’s, Canada

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Nutrition Journal 2013, 12:49  doi:10.1186/1475-2891-12-49

Published: 16 April 2013

Abstract

Background

The Food- Frequency Questionnaire (FFQ) is a dietary assessment tool frequently used in large-scale nutritional epidemiology studies. The goal of the present study is to validate a self-administered version of the Hawaii FFQ modified for use in the general adult population of Newfoundland and Labrador (NL).

Methods

Over a one year period, 195 randomly selected adults completed four 24-hour dietary recalls (24-HDRs) by telephone and one subsequent self-administered FFQ. Estimates of energy and nutrients derived from the 24-HDRs and FFQs were compared (protein, carbohydrate, fibre, fat, vitamin A, carotene, vitamin D, and calcium). Data were analyzed using the Pearson’s correlation coefficients, cross-classification method, and Bland–Altman plots.

Results

The mean nutrient intake values of the 24-HDRs were lower than those of the FFQs, except for protein in men. Sex and energy-adjusted de-attenuated Pearson correlation coefficients for each nutrient varied from 0.13 to 0.61. Except for protein in men, all correlations were statistically significant with p < 0.05. Cross-classification analysis revealed that on average, 74% women and 78% men were classified in the same or adjacent quartile of nutrient intake when comparing data from the FFQ and 24-HDRs. Bland–Altman plots showed no serious systematic bias between the administration of the two instruments over the range of mean intakes.

Conclusion

This 169-item FFQ developed specifically for the adult NL population had moderate relative validity and therefore can be used in studies to assess food consumption in the general adult population of NL. This tool can be used to classify individual energy and nutrient intakes into quartiles, which is useful in examining relationships between diet and chronic disease.

Keywords:
Food frequency questionnaire; Validity; Nutritional epidemiology