Reliability and comparative validity of a Diet Quality Index for assessing dietary patterns of preschool-aged children in Sydney, Australia.

Background/objectives: To report on the reliability and validity of a Diet Quality Index (DQI) to assess preschoolers dietary patterns using a short food frequency questionnaire (sFFQ) and 3-day food records (3d-FR).

Subjects/methods: Seventy-seven preschool carers/parents completed a telephone interview on preschoolers (2-5-year olds) dietary habits in metropolitan Sydney. Agreement in scores was assessed using intraclass correlation (ICC) and paired t-tests for repeated sFFQ-DQI scores and Bland-Altman methods and paired t-tests for sFFQ-DQI and 3d-FR-DQI scores.

Results: Mean-total sFFQ-DQI ICC scores was high = 0.89, 95% CI (0.81, 0.93). There was weak agreement between sFFQ-DQI and 3d-FR-DQI scores (r = 0.36, p < 0.01). The 3d-FR-DQI scores were positively associated with carbohydrate, folate, ß-carotene, magnesium, calcium, protein, total fat and negatively associated with sugar, starch, niacin, vitamin C, phosphorus, polyunsaturated fat, and monounsaturated fat.

Conclusions: The sFFQ-DQI demonstrated good reliability but weak validity. Associations between nutrients and 3d-FR-DQI scores indicate promising usability and warrants further investigation. Further research is needed to establish its validity in accurately scoring children's diet quality using sFFQ compared to 3d-FR before the tool can be implemented for use in population settings.