HDL-cholesterol level and mortality occurrence in the elderly: is the good cholesterol always good?

Association Between Lipid Profile Measurements and Mortality Outcomes Among Older Adults in a Primary Care Setting: A Retrospective Cohort Study

Background Lipid profile components play a role in predicting the development of cardiovascular disease and hence mortality, but recent studies have shown mixed results in the older population. The aim of our study was to investigate the association between levels of lipid profile components with all-cause mortality and cardiovascular outcomes among older adults in a primary care setting in Riyadh, Saudi Arabia. Methods A retrospective cohort study was performed among 485 individuals aged 60 years and older who visited the family medicine clinics linked to a tertiary care hospital during the first six months of 2010. The electronic charts of the participants were reviewed up to April 2022 to gather relevant data. Each lipid profile component, including total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TGs), was categorized into four quartiles. LDL was calculated using the Friedewald formula. Cardiovascular outcomes included ischemic heart disease (IHD), heart failure (HF), and stroke. Results The mean follow-up period was 12 years. The elderly participants with the lowest HDL-C quartile (<1.1 mmol/L) were at higher risk of all-cause mortality (adjusted hazard ratio of 2.023 (95% CI 1.21-3.38)) and IHD (adjusted hazard ratio 3.2 (95% CI 1.6-6.2)). High TC (≥5.7 mmol/L) was associated with an increased risk of HF (adjusted hazard ratio 2.1 (95% CI 1.1-4.0)). Conclusion In patients aged 60 years and older, low HDL-C (<1.1 mmol/L) was associated with a higher risk for all-cause mortality and IHD, and high TC was associated with an increased risk of having HF. No significant association was found for LDL-C, TC, and TGs with all-cause mortality.

Scavenger Receptor BI Induced by HDL From Coronary Heart Disease May Be Related to Atherosclerosis

This study aims to determine whether dysfunctional High Density Lipoprotein (HDL) influenced the expression of scavenger receptor class B type Ⅰ (SR-B1) to determine reverse cholesterol transport. Blood samples obtained from coronary heart disease patients confirmed by angiography were collected. HDL was extracted from the blood via ultracentrifugation. Then, the HDL was injected into apoE-/- mice, and the HepG2 cells cultured with Dulbecco's modified eagle medium (DMEM) were added the HDL extracted from coronary heart disease patients. As controls, normal cases without coronary heart disease (CHD) and patients with angina pectoris and acute myocardial infarction were used. The protein expression levels of SR-B1 were detected by western blot, and the lipid accumulation levels were detected by Oil Red O staining in both tissues and cell levels. These results revealed that the HDL obtained from CHD patients downregulate the SR-B1 expression in ex vitro and in vitro studies. In addition, dysfunctional HDL may result in lower SR-B1 expression levels. The degree of SR-B1 expression levels could be relative to the degree of coronary congestion. Along with the increase in severe coronary congestion, such as myocardial infarction, the SR-B1 expression levels were lower. The dysfunctional HDL derived from coronary heart disease patients decreased the expression of SR-B1, and promoted lipid accumulation.

Is HDL cholesterol protective in patients with type 2 diabetes? A retrospective population-based cohort study

BACKGROUND

The protective role of high HDL cholesterol levels against cardiovascular diseases has been recently questioned. Limited data are available on this specific topic in patients with type 2 diabetes mellitus (T2DM). We aimed to evaluate the association of HDL cholesterol concentrations with all-cause and cause-specific mortality in a historical cohort of T2DM patients with 14 years of follow-up.

METHODS

This is a retrospective population-based cohort study involving 2113 T2DM patients attending the Diabetic Clinic of Asti. Survival analyses were performed to assess hazard ratios for overall and specific-cause mortality by HDL cholesterol tertiles, using the middle HDL cholesterol tertile as a reference.

RESULTS

The mean age was 66 ± 11 years; 51.4% of patients had low HDL-cholesterol levels. After a 14-year follow-up, 973/2112 patients had died (46.1%). The HDL cholesterol tertile cut-off points were 37.5 and 47.5 mg/dL (males) and 41.5 and 52.0 mg/dL (females). No associations between lower and upper HDL cholesterol tertiles respectively and all-cause (HR = 1.12; 95% CI 0.96-1.32; HR = 1.11; 0.95-1.30), cardiovascular (HR = 0.97; 0.77-1.23; HR = 0.94; 0.75-1.18) or cancer (HR = 0.92; 0.67-1.25; HR = 0.89; 0.66-1.21) mortality were found. A significantly increased risk for infectious disease death was found both in the lower (HR = 2.62; 1.44-4.74) and the upper HDL-cholesterol tertiles (HR = 2.05; 1.09-3.85) when compared to the reference. Individuals in the upper tertile showed an increased risk for mortality due to diabetes-related causes (HR = 1.87; 1.10-3.15).

CONCLUSIONS

Our results corroborate the hypothesis that HDL cholesterol levels are nonprotective in T2DM patients. The U-shaped association between HDL-cholesterol levels and mortality associated with infectious diseases should be verified by further studies.