A culture-sensitive quantitative food frequency questionnaire used in an African population: 1. Development and reproducibility

Abstract

OBJECTIVE To develop and assess the reproducibility of a quantitative food frequency questionnaire (QFFQ) sensitive to the culture of the African population of the North West Province, South Africa. DESIGN A cross-sectional study. SETTING A community-based field study in a population stratified according to level of urbanization from deep rural to urban upper class. SUBJECTS A total of 144 (99 women and 45 men) residents of the North West Province, aged between 15 and 65 years. participated in the study. METHODS A culture-sensitive. 145-item interviewer-administered QFFQ was designed to cover the whole diet. Portion sizes were estimated from a food portion photograph book (FPPB) showing foods in three portion sizes. The QFFQ was administered twice, 6-12 weeks apart. RESULTS Spearman rank correlation coefficients between the two administrations varied from 0.14 for calcium to 0.75 for alcohol. The mean percentage difference between intakes was 8.5 (standard deviation= 9.9). Energy. protein, carbohydrate and calcium gave differences within 10%. Few significant differences among correlation coefficients or percentage difference for gender, age group or strata of urbanization were present. Bland-Altman plots showed significant proportional bias for protein, fibre and vitamin C. More than 70% of the participants were classified into adjacent quintiles for all nutrients. For food groups, correlation coefficients ranged from 0.25 for milk to 0.45 for vegetable and maize meal groups and 809/a of participants were classified into adjacent quintiles. CONCLUSIONS The QFFQ appeared to be a reproducible dietary intake assessment instrument.