Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author. 1 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 Maryam Delshad Siyahkaly 2016 2 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 A, vitamin D, folate (P < 0.05), 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)’. 3 Acknowledgements I would like to sincerely thank the following people for their contributions to this research and report: My supervisors, Dr. Cath Conlon, Dr. Kathryn Beck, and Dr. Pamela von Hurst for their constant encouragement, patience, support, and guidance. Owen Mugridge for his support in recruiting participants and data collection. The participants of this study for their time and commitment to the research. My husband for his ongoing support and encouragement. 4 Table of Contents Abstract .............................................................................................................................. 2 Acknowledgements ........................................................................................................... 3 List of tables....................................................................................................................... 6 List of figures ..................................................................................................................... 7 List of abbreviations ......................................................................................................... 8 Chapter 1: Introduction ................................................................................................. 10 1-1. Aim .................................................................................................................... 14 1-2. Objectives .......................................................................................................... 14 1-3. Hypothesis ......................................................................................................... 14 1-4. Structure of thesis .............................................................................................. 14 1-5. Researchers’ contribution .................................................................................. 15 Chapter 2: Literature review ......................................................................................... 17 2-1. Dietary intake/quality in children ...................................................................... 18 2-2. Dietary assessment in children .......................................................................... 19 2-3. Analysis of dietary data ..................................................................................... 25 2-4. Dietary pattern analysis ..................................................................................... 27 2-5. Previous research on diet quality indices .......................................................... 33 2-6. Development of a diet quality index.................................................................. 40 2-7. Selection and type of index components ........................................................... 40 2-8. Cut-off values and scoring of index .................................................................. 42 2-9. Validity and reliability of diet quality indices ................................................... 44 2-10. Statistical analysis............................................................................................ 46 2-11. Summary .......................................................................................................... 48 Chapter 3: Methods ........................................................................................................ 50 3-1. Study design ...................................................................................................... 51 3-2. Ethical approval ................................................................................................. 51 3-3. Participants ........................................................................................................ 51 3-4. Study procedures ............................................................................................... 51 3-5. Overview of the New Zealand Food and Nutrition Guidelines for Healthy Children and Young people (Aged 2-18 years old) .................................................. 52 3-6. Dietary Index for a Child’s Eating (DICE) components, scoring, and cut-off points ......................................................................................................................... 55 3-7. Data handling and data analysis ........................................................................ 61 3-8. Statistical analysis.............................................................................................. 63 Chapter 4: Results........................................................................................................... 66 5 4-1. Dietary Index for a Child’s Eating (DICE) Scores ............................................ 67 4-2. Relative validity of DICE .................................................................................. 71 4-3. Construct validity of DICE ................................................................................ 74 4-4. Reliability of DICE ............................................................................................ 78 Chapter 5: Discussion and conclusion........................................................................... 79 5-1. Description of Dietary Index for a Child’s Eating (DICE) scores .................... 80 5-2. Relative validity (DICE vs. 4DFR) ................................................................... 81 5-3. Construct validity of DICE ................................................................................ 83 5-4. Reliability of DICE ............................................................................................ 85 5-5. Methodological issues ....................................................................................... 86 5-6. Strengths and limitations ................................................................................... 91 5-7. Recommendation for further research ............................................................... 92 5-8. Conclusion ......................................................................................................... 92 References ........................................................................................................................ 94 Appendix ........................................................................................................................ 110 Appendix A. Information sheet............................................................................... 111 Appendix B. Consent form ..................................................................................... 114 Appendix C. Four day food record ......................................................................... 115 Appendix D. Dietary Index for a Child’s Eating (DICE) ....................................... 135 Appendix E. Assumptions and decisions made from the 4DFR for each index component ............................................................................................................... 142 6 List of tables Table 2-1. Dietary assessment methods .......................................................................... 24 Table 2-2. Definitions of the nutrient references values (NRVs) ................................... 26 Table 2-3. Types of dietary pattern analysis methods ...................................................... 32 Table 2-4. Overview of diet quality indices, which have been designed for children (n = 13 indices) ........................................................................................................................ 37 Table 3-1. Food and nutrition guidelines for healthy children and young people (Aged 2- 18 years) ............................................................................................................................ 54 Table 3-2. Components of the DICE and scoring system ................................................ 60 Table 4-1. Participants’ distribution scores from 100 score according to DICE (n = 65) 67 Table 4-2. Frequency of participants in each scoring group for DICE component sub- scores, and Spearman correlation of each index component with total score (n = 65)..... 69 Table 4-3. Pearson correlation and cross-classification between total DICE score and 4DFR score ....................................................................................................................... 71 Table 4-4. Comparison of sub-scores for each component and Spearman correlation coefficients and agreement between each component from first administration of DICE with the same component from 4DFR (n = 63) ................................................................ 73 Table 4-5. Spearman correlations between the DICE (total score and individual components) with energy and nutrient intakes derived from the 4DFR (n = 65) ............. 76 Table 4-6. 4DFR dietary intakes categorized by tertiles of the DICE (n = 63) ............... 77 Table 4-7. Reliability of the DICE (n = 49) ..................................................................... 78 7 List of figures Figure 4-1. The first administration of DICE scores and 4DFR scores ….......................74 8 List of abbreviations Adequate Intake AI Australian Child and Adolescent Recommended Foods Score ACARFS Australian Recommended Food Scores for Preschoolers ARFS-P Brazilian Healthy Eating Index Revised BHEI-R Coronary Heart Disease CHD Diet Quality Index DQI Diet Quality Index for Adolescents DQI-A Diet Quality Index for NZ Adolescents Diet Quality Index for Preschool Children NZDQI-A DQI-CH Diet Quality Index-International DQI-I Dietary Guideline Index for Children and Adolescents DGI-CA Dietary Index for a Child’s Eating DICE Estimated Average Requirement Eating Choices Index EAR ECI Finnish Children Healthy Eating Index FCHEI Food Frequency Questionnaire FFQ Food-Based Dietary Guidelines FBDG Four day Food Record 4DFR Gram g Healthy Eating Index HEI Healthy Eating Index for Canadian HEI-C Healthy Eating Index-2005 HEI-2005 High Fat, Sugar, and Salt foods and snacks HFSS Intra-class Correlation Coefficient ICC Kilo calories Kolmogorov-Smirnov Kcal K-S Mediterranean Diet Quality Index for children and adolescents KIDMED Mediterranean Diet Score MDS Mediterranean Lifestyle Index MEDLIFE 9 Microgram g Milligram mg Monounsaturated Fatty Acids MUFA New Zealand NZ Number n Nutrient Reference Values NRVs Nutrient-Rich Food index NRF-index P-value P Polyunsaturated Fatty Acids PUFA Preschoolers Diet–Lifestyle Index PDL-Index Recommended Dietary Intakes RDI Revised Children’s Diet Quality Index RC-DQI Saturated Fatty Acids SFAs Serving per day Shapiro-Wilk Serve/d S-W Standard Deviation Statistical Package for the Social Science SD SPSS Television Trans Fatty Acids TV TFAs Update the Healthy Eating Index-C 2009 Upper Level of Intake HEIC-2009 UL US Department of Agriculture USDA Youth Healthy Eating Index YHEI