Longitudinal Comparison of Cholesterol Ratio with Non-HDL Cholesterol on Incident Ischemic Heart Disease: A Cohort of Nondiabetic Koreans

Background/Objectives: Non-HDL cholesterol (non-HDL-C) and the ratio of total to HDL cholesterol (TC/HDL-C ratio) are two readily available lipid indices, but their comparative associations with incident ischemic heart disease (IHD) have rarely been examined directly in nondiabetic Asian populations. Methods: This study followed 14,728 nondiabetic Korean adults from the HERAS-HIRA cohort for a mean of 2.2 ± 1.1 years (median: 2.3 years), with participants grouped into quartiles of each index. Hazard ratios (HRs) for incident IHD were estimated using multivariable Cox proportional hazards models. Results: During follow-up, IHD occurred in 271 participants (1.8%). Compared with the lowest quartile, the highest quartile was associated with a higher adjusted risk of IHD for both the TC/HDL-C ratio (HR: 2.81, 95% CI: 1.70–4.65) and non-HDL-C (HR: 1.74, 95% CI: 1.13–2.69). In marker-only, unadjusted ROC analysis, the TC/HDL-C ratio had a slightly higher AUC than non-HDL-C did (0.628 vs. 0.600, p = 0.023), although both values indicated modest dis-crimination; the exploratory, sample-derived cutoffs were 3.6 and 142 mg/dL, respectively. Conclusions: Both indices were associated with incident IHD, but the TC/HDL-C ratio showed only slightly better unadjusted discrimination; adjusted time-to-event prediction analyses and external validation are needed before additional clinical utility can be inferred.