Objectives To evaluate the reliability and validity of a culture-specific semi-quantitative food frequency questionnaire (FFQ) in assessing nutrient intake estimates of the adult population of Trinidad and Tobago. Methods An electronic 154-item semi-quantitative FFQ was created using Google forms to reflect the culture-specific and street foods consumed by persons living in Trinidad and Tobago. The self-administered FFQ was emailed twice, 3 months apart, to 91 participants ≥18 years. The first FFQ was validated against 4 one-day food records with digital images which served as the reference method. Using SPSS Version 26, the validity and reproducibility of the FFQ's nutrient intake estimates were determined using paired t-tests, bivariate correlations and cross-classifications. Correlations were calculated on energy-adjusted nutrients. Cross-classification was used to show agreement between the FFQ and weighted average food records. Results Participants consisted of 22% male and 78% females, median age 38 ± 10 years. Intake estimates of nutrients in both administrations of the FFQ were highly reproducible: Correlations ranged from medium (r = 0.58, P ≤ 0.0001, for vitamin C) to high (r = 0.83, P ≤ .0001, for carbohydrates); cross-classification agreements within ±1 quintile ranged from 69% (cholesterol) to 89% (fiber and vitamin A). For validity, the energy-adjusted correlations average was r = 0.37, with correlations (r) ranging from 0.22 (P ≤ .050, polyunsaturated fatty acids (PUFA)) to 0.67 (P ≤ .0001, cholesterol). Cross-classification showed that an average of 61% of the FFQ estimates were correctly classified within ±1 quintile of exact agreement in the food records. Agreements between the FFQ and the food records ranged from 48% for calcium to 71% for cholesterol, all significant at P ≤ 0.0001. Conclusions The culture-specific FFQ has a good level of reliability and validity for use in future studies to assess nutrient intake of adults living in Trinidad and Tobago. Funding Sources N/A.

Background Nutritional epidemiologists use culture-specific food frequency questionnaires (FFQs) to assess the dietary intake of groups based on country, region or ethnic groups. The aim of this study was to assess the performance of a self-constructed culture-specific semi-quantitative electronic FFQ (e-FFQ) in assessing food group intake estimates when compared with multiple 1-day food records (FRs) for the adult population of Trinidad and Tobago. Methods The 139-item semi-quantitative e-FFQ containing local dishes and street foods was created using Google forms. It was emailed twice, 3 months apart, to 91 participants ≥ 18 years of age. The first administration of the e-FFQ was validated against 4-four one-day FRs with digital photographs which served as the reference method. Using SPSS Version 26, the validity and reproducibility of the FFQ’s food group intake estimates were determined using paired t-tests, bivariate correlations, and cross-classifications. Cross-classification and Bland-Altman plots were used to show agreement between the e-FFQ and weighted mean of the FRs. Results Participants consisted of 22% males and 78% females, mean age 38 ± 9.6 years. Reproducibility correlations between the reported food group intakes in the first and repeat administration of the e-FFQ ranged from moderate (r = 0.44 p ≤ 0.0001) for sweetened beverages to high (r = 0.91 p ≤ 0.0001) for alcohol. Cross-classification agreements within ± 1 quintile ranged from 70% (street foods) to 92% (alcohol). Crude validity correlations between the e-FFQ and FR ranged from (r = 0.06) for sweets to (r = 0.65) for food from animal sources, with mean of the validity correlations being 0.34. Deattenuated correlations ranged from r = 0.11 for sweets to r = 0.81 for food from animal sources. Cross-classification showed that an average of 68% of the FFQ estimates were correctly classified within ± 1 quintile of exact agreement in the FRs. Agreements between the FFQ and the FRs ranged from 55% for street foods to 95% for water, all significant at p ≤ 0.0001. Conclusions The study shows that this culture-specific e-FFQ is highly reproducible and is a reasonably valid tool to assess and rank food group intake estimates of an adult population living in Trinidad and Tobago. Thus, it can be used to examine associations between dietary intakes and NCDs.