The Korean Dietary Diversity Score (KDDS) as an Indicator of Dietary Adequacy and Its Relationship with Frailty in Elderly: the Korean Frailty and Ageing Cohort Study (KFACS)

Abstract

[Background] Frailty is a common condition that results from cumulative decline in many physiological systems during a lifetime. It has been associated with an increased risk of several deleterious outcomes in that population, including disability, hospitalization and institutionalization. Although the risk factors for frailty are numerous, diet could play its own relevant role in its development. People eat food, rather than nutrients, and no previous study has examined the association between dietary diversity empirically derived from food consumption and the risk of frailty in Korean elderly. [Objectives] The objectives of this study were to evaluate the KDDS as an indicator of nutrient adequacy in Korean elderly, and to examine the association of KDDS, and the prevalence and incidence of frailty from the Korean Frailty and Ageing Cohort Study (KFACS).

[Method] This is a prospective cohort study of 1,000 (484 men and 516 women) participants aged 70-84 years, who are recruited in 2016. Of these participants, 955 subjects were included in analysis to indicate an association between KDDS and prevalence of frailty. A 709 participants who did not have frailty in the baseline survey were included in the final analysis. The Korean dietary diversity score (KDDS) was computed from a 24-hr dietary recall with 6 food groups (scored 0-6). Frailty was defined as having at least three out of the following five slightly modified Fried frailty criteria: involuntary weight loss, exhaustion, slowness, weakness and low physical activity. Generalized estimating equation was used to estimate prevalence ratio (PR) and 95% CI. Logistic regression models adjusting for potential confounders were used to assess the association between KDDS and development of frailty. [Results] The KDDS score has significant positive correlation with mean adequacy ratio (MAR) in men (r=0.460, p<0.0001) and women (r=0.481, p<0.0001). When maximizing sensitivity and specificity, the best cut-off point for achieving 40% of MAR was about 5 for KDDS. In fully adjusted model, there was a significant inverse relationship between KDDS categories and the prevalence of frailty (P for trend=0.0008), exhaustion (P for trend=0.0040) and slowness (P for trend=0.0205). Over a 2-year follow-up, 128 cases of incident frailty were ascertained. After adjustment for age, sex, comorbidity (diabetes and dyslipidemia), education level and components of frailty at baseline, high-KDDS group was associated with decreased risk of frailty (PR=0.50, 95% CI=0.32-0.78). Regarding the components of frailty separately, the high-KDDS group was associated with a significantly reduced risk of incident weakness (PR=0.57, 95% CI=0.36-0.90), slowness (PR=0.66, 95% CI=0.46-0.93) and low activity (PR=0.48, 95% CI=0.34-0.67), compared to the low-KDDS group. Also, the PR (95% CI) of frailty among those in 4 categories of KDDS were 1.00, 0.59 (0.29-1.19), 0.31 (0.15-0.62), and 0.45 (0.20-1.02), respectively; P for trend=0.0025. Each additional unit of KDDS score was associated with a significantly decreased risk of frailty (PR=0.72, 95% CI=0.58-0.89), weakness (PR=0.80, 95% CI=0.64-0.94), slowness (PR=0.79, 95% CI=0.66-0.94) and low activity (PR=0.67, 95% CI=0.57-0.80).

[Conclusion] These findings support that KDDS is a useful indicator of nutrient adequacy of the elderly in Korea, and high dietary diversity is associated with the risk of frailty in Korean elderly. Further research is required to evaluate it use in epidemiologic research and public health interventions in terms of evaluating dietary change, predicting disease risk and considering more diverse populations.