Association Between the Korean Healthy Eating Index (KHEI) and Healthcare Costs Among Adults: The Korea National Health and Nutrition Examination Survey (KNHANES) 2016 and 2021.

BACKGROUND/OBJECTIVES: This cross-sectional study examined the association between diet quality, measured by the Korean Healthy Eating Index (KHEI), and medical expenditures among Korean adults.

METHODS

We used data from the Korea National Health and Nutrition Examination Survey (2016-2021). Adults aged ≥20 years with complete data on diet, sociodemographics, and healthcare use were included. Medical costs were estimated from self-reported service use and converted to USD. KHEI scores were categorized into quartiles. Multivariable linear regression was used to assess the association between KHEI quartiles and log-transformed costs. Subgroup analyses were conducted by age (<57 vs. ≥57 years), and sensitivity analyses treated KHEI as a continuous variable. A two-part model addressed skewed, zero-inflated cost data.

RESULTS

Compared to Q1, participants in Q4 had significantly lower inpatient (β = -0.080; 95% CI: -0.139 to -0.020) and total costs (β = -0.086; 95% CI: -0.144 to -0.027). In the younger group, Q4 was associated with lower total costs (β = -0.115; 95% CI: -0.198 to -0.031). Higher continuous KHEI scores were also linked to lower costs. In the two-part model, Q4 participants had a higher probability of incurring any cost but lower conditional costs (Q3 vs. Q1: β = -0.173; Q4 vs. Q1: β = -0.160; both < 0.05).

CONCLUSIONS

Higher diet quality was associated with reduced healthcare costs in Korean adults, especially among younger individuals. Promoting healthy eating may help lower economic burdens in aging societies.