Differences in HDL-related mortality risk between individuals with and without hypertension: a prospective cohort study in UK Biobank

Background and aims Very high levels of high-density lipoprotein cholesterol (HDL-C) have been paradoxically linked to increased mortality risk. The present study aimed to examine associations of HDL-C and varied sizes of the HDL particle (HDL-P) with mortality risk stratified by hypertension. Methods and results This prospective cohort study included 429 792 participants (244 866 with hypertension and 184 926 without hypertension) from the UK Biobank. During a median follow-up of 12.7 years, 23 993 (9.8%) and 8142 (4.4%) deaths occurred among individuals with and without hypertension, respectively. A U-shaped association of HDL-C with all-cause mortality was observed in individuals with hypertension after multivariable adjustment, whereas an L-shape was observed in individuals without hypertension. Compared with individuals with normal HDL-C of 50-70 mg/dL, those with very high HDL-C levels (>90 mg/dL) had a significantly higher risk of all-cause mortality among individuals with hypertension (hazard ratio, 1.47; 95% confidence interval, 1.35-1.61), but not among those without hypertension (1.05, 0.91-1.22). As for HDL-P, among individuals with hypertension, a larger size of HDL-P was positively whereas smaller HDL-P was negatively associated with all-cause mortality. After additional adjustment for larger HDL-P in the model, the U-shaped association between HDL-C and mortality risk was altered to an L-shape among individuals with hypertension. Conclusions The increased risk of mortality associated with very high HDL-C existed only in individuals with hypertension, but not in those without hypertension. Moreover, the increased risk at high HDL-C levels in hypertension was likely driven by larger HDL-P. Lay Summary This study examined the potential modification of hypertension on associations of high-density lipoprotein cholesterol (HDL-C), especially at a very high level, and varied sizes of HDL particle (HDL-P) with the risk of mortality.Very high HDL-C levels were associated with increased risk of mortality in individuals with hypertension, but not in those without hypertension.In individuals with hypertension, the increased risk at a high HDL-C level was attributed to a larger size of HDL-P, which was directly associated with mortality risk. An inverse association with mortality was observed for a smaller size of HDL-P.