Measuring diet quality in China: The INFH-UNC-CH diet quality index

Objective: This paper describes the development and efficacy of a diet quality index (DQI) for China. Design: The Dietary Guidelines for Chinese Residents motivated the selection of 10 DQI components. These components were weighted and assigned cut-offs and point schemes based on the Chinese Food Guide Pagoda, Chinese and/or international dietary reference values. The efficacy of resulting DQI scores was assessed relative to a priori expectations. Subjects: The Chinese DQI was evaluated using cross-sectional 3 day diet record and anthropometric data on 7450 adults from the 1991 China Health and Nutrition Survey. Methods: For each individual, a DQI total score was calculated as the sum of components, and DQI pattern scores calculated to reflect the underlying composition of diet quality problems. The DQI scores were compared with component scores, food and nutrient intake, weight status and sociodemographic variables. Results: The total DQI score simultaneously represented all component aspects of diet quality as well as micronutrients not explicitly built into the index. The total DQI score was significantly correlated with food and nutrient intakes, BMI, urban residence and income. The DQI pattern scores correlated with DQI components and weight status as expected. Conclusions: The China DQI captures variation along several components of diet quality, appears sensitive to under- and overnutrition, as well as sociodemographic variables. The China DQI may prove useful for monitoring the nutrition transition and epidemiologic trends in China.