Relative Validity and Reproducibility of a Dietary Screening Tool in Nigerian Health Care

Background: Hypertension and cardiovascular disease burden are rising rapidly in Nigeria. This trend is partly attributed to a transition from healthy to unhealthy dietary patterns. However, health care professionals lack a dietary screening tool to assess patient dietary intake and offer personalized dietary advice. Objectives: We aimed to develop and validate a food frequency questionnaire (FFQ) that can quickly and accurately assess regional dietary intake for use by health care professionals in a hospital setting in Port Harcourt, Nigeria. Methods: We recruited 58 patients from a single hospital in Nigeria. The FFQ was administered at baseline and again after 3 wk. To evaluate the validity of the FFQ, we used 3 repeated and nonconsecutive 24-h dietary recalls (24DR) as a reference method. Spearman rank correlations, Wilcoxon signed-rank tests, cross-classification, intraclass correlation coefficients (ICCs), and Bland-Altman analysis were performed in R software version 4.3.1 to assess the relative validity and reproducibility. Results: The mean correlation coefficient (r(s)) between the FFQ and 24DR was 0.60 (P < 0.05), and ranged from 0.20 to 0.78. The Wilcoxon signed-rank tests indicated no significant differences in the 19 food groups queried (P > 0.05), except for fats and oils (P < 0.05). The exact agreement for classifying individuals into quartiles ranged from 17% for salt to 88% for processed meats and alcoholic drinks, with 90% of individuals classified into the same or neighboring quartile. Additionally, the Bland-Altman analysis demonstrated acceptable agreement, with >96% of observations within the acceptable limits of agreement for all food groups. For reproducibility, the ICC ranged from 0.31 for stew to 0.98 for fruit, with an mean ICC of 0.77 between the FFQs delivered 2 wk apart. Conclusions: Our results support the use of the FFQ as a valid and reliable tool for ranking intakes of certain food groups among patients in a hospital setting in Nigeria.