Comparing common summary measures of the quality of diets in Canadian children
Creators: Panahimoghadam, Seyedehatefeh
Publisher: name: University of Alberta Library
Year: 2024

<p>Background: Despite some improvements, many Canadian children still fail to meet dietary guidelines, lacking sufficient intake of fruit and vegetables while consuming high-fat, high-sugar foods, and excessive sodium. Establishing healthy dietary habits in childhood reduces the risk of obesity and chronic diseases in adulthood, improves academic performance and overall quality of life, and substantially reduces healthcare costs. Employing an optimal index enables accurate diet quality assessment and guides future interventions to improve children&#39;s overall diet and health status. Previous studies were mainly conducted outside of Canada, evaluating indices different from those commonly employed within the country. They mostly focused on evaluating diet quality indices among adults and applied methods that had several limitations. <br>
Objective: This thesis aimed to compare the properties of common summary measures of diet quality in Canada, including Healthy Eating Index-Canada 2015 (HEI-C 2015), Diet Quality Index-International (DQI-I), and Healthy Eating Food Index 2019 (HEFI-2019) among school-age Canadian children. The specific objectives of this thesis were examining and comparing: 1) score variations of HEI-C 2015, DQI-I, and HEFI-2019; 2) the level of agreement across the diet quality indices; 3) the ability of the diet quality indices to differentiate between groups with known diet quality differences; and 4) the capacity of diet quality indices to assess diet quality independent of diet quantity based on the diet quality of Canadian children.<br>
Methods: To achieve these objectives, dietary information obtained from 1,699 grade 4-6 students through validated web-based 24-hour diet recall surveys conducted in 2016, 2018, and 2020/2021 as part of the APPLE Schools program was used. The agreement between the indices was evaluated through weighted Cohen&#39;s Kappa. Univariable and multivariable linear regression models were applied to estimate the potential difference in conclusions resulting from each index&#39;s application.<br>
Results: The study presented in this thesis revealed wider ranges (and coefficients of variation [CVs]) for HEI-C 2015 (11.7-95.3 [25.7]) and HEFI-2019 scores (8.6-90.1 [30.1]) compared to DQI-I scores (19.9-83.9 [18.1]). Overall, only fair agreement was revealed between HEI-C 2015 and HEFI-2019 (Weighted Cohen&#39;s Kappa coefficient [Kw]=0.38; 95% confidence Interval [CI]: 0.35, 0.42), and between HEFI-2019 and DQI-I (Kw=0.29; 95%CI: 0.25, 0.33), while moderate agreement was found between HEI-C 2015 and DQI-I (Kw=0.55; 95%CI: 0.52, 0.59). Regardless of the index used, girls demonstrated better diet quality than boys, with DQI-I being the most effective index in differentiating between sexes&#39; diet quality. Grade levels could not discriminate between students&#39; diets using any of the three indices. All three indices indicated lower diet quality among students in materially deprived neighbourhoods, with HEI-C 2015 showing the strongest association. Conversely, higher DQI-I scores were associated with more socially deprived areas. Students in smaller geographic regions exhibited slightly better diet quality, with HEI-C 2015 indicating the most robust association. When comparing the abilities of indices to identify diet quality independent of diet quantity, higher energy consumption was associated with higher DQI-I and lower HEFI-2019 scores.<br>
Conclusions: The results of this thesis underscore the importance of selecting the most optimal diet quality index for Canadian school-age children to ensure a precise interpretation of their diet quality. Researchers, practitioners, and policymakers must agree on a suitable diet quality index for Canadian children due to its importance in dietary research and interventions, and dietary guidelines development. HEFI-2019 is the most recent Canadian diet quality index, aligning with the latest Canadian Food Guide (CFG-2019). The index displayed notable strengths in this study, such as large score variability and the ability to differentiate between the diet quality of children residing in areas with different material deprivation levels. However, its scoring standards need to be more age-specific, and its dependence on energy intake should be addressed in future research endeavours.</p>