Very high high-density lipoprotein cholesterol is associated with increased all-cause mortality in South Koreans

Background and aims: Our study aimed to investigate the association between high-density lipoprotein cholesterol (HDL-C) and all-cause and cause-specific mortality in Korean adults. Methods: A total of 365,457 participants aged >= 40 years were selected from the Korean National Health Insurance Service-National Sample Cohort from 2009 to 2015. HDL-C level was categorized into< 1.0, 1.0-1.19, 1.2-1.39, 1.4-1.59, 1.6-1.79 (reference), 1.8-1.99, 2.0-2.19 and >= 2.20 mmol/L. Cox proportional hazard models were used to examine the association between HDL-C level and mortality risk. Results: In a median 3.5-year follow-up period, 9,350 participants (2.6%) died. Men with HDL-C level of 1.6-1.79 mmol/L and women with HDL-C level of 1.4-1.59 mmol/L had the lowest age-standardized mortality rates for all-cause death. However, for cardiovascular death, men with HDL-C level >= 2.20 mmol/L and women with HDL-C level of 1.8-1.99 mmol/L showed the lowest mortality rate. After adjusting for multiple covariates, the hazard ratios for all-cause and cancer deaths showed a U-shaped relationship with HDL-C level for both sexes. However, there were heterogenetic associations between HDL-C level and mortality risk of subtypes of cardiovascular disease by sex. For other causes of death except for cardiovascular and cancer death, elevated mortality risk was mainly due to external causes (ICD-10 code, S00-T98). Conclusions: In South Korea, very high HDL-C level was associated with increased risk of all-cause death. However, the increased all-cause mortality risk in people with very high HDL-C level was partly due to mortality risk from external causes.