Background: Diet quality in early childhood has a long-term impact on health outcomes. However, there are scarce dietary indexes for Chinese preschool children, and the existing indexes had limited validity and reliability. This study thus aimed to develop a dietary index for preschool children based on the Chinese Dietary Guideline and Chinese Dietary Reference Intakes and to assess their overall diet quality using the China Health and Nutrition Survey (CHNS).

Methods: The Chinese Preschooler Dietary Index (CPDI) included 11 components, covering 9 food group components and two nutrient components. The total scores of CPDI ranged from 0 to 90, with a higher score indicating greater diet quality. This study assessed the diet quality of 1742 preschoolers aged two to five years old from CHNS using the CPDI. Dietary intake data were obtained using three-day 24-h diet recalls, and sociodemographic information was also collected. Cochran-Mantel-Haensel (CMH) test was used to explore the association between demographic and CPDI total scores. The principal component analysis, correlation analysis and Cronbach's alpha were used to evaluate the relative reliability and validity of the CPDI. Finally, a stepwise multiple regression analysis was performed to explore potential influencing factors of CPDI.

Results: Among the 1742 CHNS preschool children, more than 70% resided in rural areas and 41.2% of the sample were raised in a low-income family. The mean CPDI score of the preschoolers was 38.8 ± 12.9. Higher diet scores were correlated with higher energy and nutrient intake. Children with higher age (β = 0.93, SE = 0.26, P = 0.0003), raised in a home with higher household income (β = 3.11, SE = 0.27, P < 0.0001) or living in urban areas (β = -4.44, SE = 0.66, P < 0.0001) were associated with higher CPDI scores.

Conclusions: The CPDI is useful in evaluating the diet quality of preschool children. Based on the CPDI, the diet quality of Chinese preschoolers needs to be improved, especially in rural areas.