Validity and reliability of a Dietary Index for a Child's Eating (DICE) to assess diet quality of children living in New Zealand : a thesis presented in partial fulfillment of the requirement for the degree of Master Science in Human Nutrition at Massey University, Albany, New Zealand

Abstract

Background: At present, in New Zealand, there is no valid and reliable dietary index, which can assess the adherence of children to the ‘New Zealand Food and Nutrition Guidelines for Healthy Children and Young People (Aged 2 -18 years)’. Aim: To examine the validity and reliability of the Dietary Index for a Child’s Eating (DICE) in children aged 2 to 8 years living in Auckland, New Zealand. Methods: Caregivers of healthy children (2-8 years) living in NZ were recruited by email and print advertising. Caregivers completed a four day estimated food record (4DFR) for their child, and completed the DICE online on 2 separate occasions, eight weeks apart. The DICE consists of 17 questions that refer to current statements in the ‘New Zealand Food and Nutrition Guidelines for Healthy Children and Young People (Aged 2-18 years)’, with greater adherence to guidelines indicated by a higher score (maximum 100). The 4DFR was the reference method for assessing validity of the DICE, and the repeated completion of the DICE questionnaire for assessing its reliability. Relative validity was assessed by comparing the DICE total score and component sub-scores with 4DFR total score and the same 4DFR component sub-scores from the questionnaire using Wilcoxon signed rank test, Spearman correlation coefficients, cross-classification, and weighted kappa (ĸ) statistic. For evaluating construct validity, the DICE (total score and individual components) were compared with energy and nutrient intake extracted from the 4DFR using Pearson’s rank correlation coefficient and linear contrast analysis. Intra-class correlation coefficients (Cronbach's α) were used to assess the reliability of DICE. Results: From a possible score of 100, the mean ± SD of DICE was 78.2 ± 11.5 (range from 47 to 100) and the 4DFR was 73.8 ± 10.8. Pearson’s correlation coefficient showed a significant, high correlation between the total scores for DICE and 4DFR (r = 0.72; P < 0.001). Results from the weighted ĸ-statistic also showed that the DICE total score and 4DFR total score had very good agreement (ĸ = 0.94). There was a significant positive relationship between the DICE total score and vitamin C (r = 0.53), folate (r = 0.45), and calcium (r = 0.44) (P < 0.001). Results from linear contrast analysis showed that higher intake of fibre, vitamin C, vitamin , vitamin D, folate (P 0.0 ), and calcium (P 0.001) were associated with increasing tertile of the DICE total score. Almost perfect agreement (0.87) was found through the Intra-class correlation coefficient for reliability test (P < 0.001). Discussion and Conclusion: Results from this study demonstrated that DICE is a valid and reliable tool for the assessment of children’s adherences to a health-promoting diet, as suggested in the ‘New Zealand Food and Nutrition Guidelines for Healthy Children and Young People (Aged 2 -18 years)’.