The development of diet quality index using Korean dietary guideline and its relationship with mortality in HEXA

Abstract

Introduction: Diet quality scores or indices, which are based on assessment of compliance with dietary guidelines, are used to summarize dietary intake into a single numeric variable. The aim of this study was to develop a diet quality index for Koreans and evaluate the relationship between diet quality and mortality. Methods: A new diet quality index for Koreans (DQI-K) was developed based on the assessment of compliance with Korean dietary guidelines. The construct validity of the DQI-K was evaluated by examining the relation between the DQI-K and selected characteristics and intake of food groups. Additionally, the DQI-K was compared with other diet quality indices. The association between all-cause and cause-specific mortality and the DQI-K was examined in Coxs proportional hazard regression models. Results: The DQI-K was based on 8 components: 1) daily protein intake, 2) percent of energy from fat, 3) percent of energy from saturated fat, 4) daily cholesterol intake, 5) daily whole-grain intake, 6) daily fruit intake, 7) daily vegetables intake and 8) daily sodium intake. In the construct validity test, good diet quality according to the DQI-K was correlated with being older, having higher educational level and higher income. The magnitude of correlation with macronutrients density was greater in the DQI-K than in the Diet Quality index (DQI) or Korean Diet Score (KDS). In multivariate adjusted models, poor diet quality according to the DQI-K was associated with all-cause mortality in men and women (HR=1.35, 95% CI=1.09-1.67 in men and HR=1.19, 95% CI=1.02-1.40 in women). Furthermore, poor diet quality significantly increased the risk for gastric cancer mortality in men (HR=3.10, 95% CI=1.41-6.78), while poor diet quality significantly increased the risk for colorectal cancer among women (HR=4.17, 95% CI=1.25-13.97) after multivariate adjustment. Conclusions: The DQI-K developed in the present study can be used to assess the diet quality of Koreans. It is possible to examine the effect of compliance with the diet guidelines for Koreans on health outcomes using the DQI-K.