Predicting coronary risk in the general population--is it necessary to measure high-density lipoprotein cholesterol?

BACKGROUND: The Joint British Societies Coronary Risk Prediction Charts recommend the use of a high-density lipoprotein cholesterol value of 1 mmol/l where actual values have not been measured. It is important to quantify the impact of this advice if risk assessments are to be sufficiently accurate to guide treatment decisions. DESIGN: The risks of 5005 individuals from the Health Survey for England 1998 were calculated using the Joint British Societies charts. Each individual's risk was recalculated assuming a high-density lipoprotein cholesterol value of 1 mmol/l. These risk estimates were compared with those derived from the Framingham equation. METHODS: Using the Framingham equation as the gold standard, the positive and negative predictive values, sensitivity and specificity with 95% confidence intervals of the Joint British charts with actual and estimated high-density lipoprotein cholesterol values were calculated. RESULTS: At the 30% 10-year coronary heart disease risk threshold using measured high-density lipoprotein cholesterol values, the charts had a sensitivity of 83% and specificity of 99%. Using an estimated high-density lipoprotein cholesterol value of 1 mmol/l reduced the sensitivity to 58% with a specificity of 98%. CONCLUSIONS: In the presence of measured high-density lipoprotein cholesterol values there was good agreement between the Framingham equation and the Joint British Societies charts. The use of a fixed high-density lipoprotein cholesterol value of 1 mmol/l introduced important and significant errors into the risk assessment. This study reinforces the need to measure both total and high-density lipoprotein cholesterol when assessing coronary risk.     

Do Turkish adults really have lower serum levels of high-density lipoprotein cholesterol?

BACKGROUND: Coronary heart disease is the leading cause of death in Turkey. The Turkish Heart Study and TEKHARF study have been carried out at various times and in different parts of Turkey and have suggested that the Turkish population has a low high-density lipoprotein-cholesterol (HDL-C) level. However, in our daily practice, mean HDL-C levels were not as low as previously reported. Here, we investigated the lipid profile, especially the HDL-C level, in the population of the Duzce region of northwest Turkey. METHODS: Serum triglyceride, total cholesterol, and HDL-C levels were measured in 674 healthy volunteers (398 women and 276 men); low-density lipoprotein cholesterol (LDL-C) levels were calculated using the Friedewald equation. RESULTS: The mean serum HDL-C level was 46.1 +/- 9.8 mg/dl in men and 53.2 +/- 10.7 mg/dl in women; these values are higher than expected based on the Turkish Heart Study. The mean serum total cholesterol level was 196.7 +/- 43.2 mg/dL in men and 198.4 +/- 43.9 mg/dL in women; the mean LDL-C level was 119.6 +/- 34.9 mg/dL in men and 118.7 +/- 34.1 mg/dL in women; and the mean serum triglyceride level was 151.4 +/- 80.9 mg/dL in men and 132.1 +/- 68.9 mg/dL in women. CONCLUSIONS: Our finding that the HDL-C level in this population was higher than the previously reported levels in Turkey indicates that HDL-C levels may not be as low as previously thought. We believe that lower HDL-C levels that were previously reported might be due to the difference between techniques of analysis, nutritional status, and percent of subjects who were fasting in the day of analysis or improper subject inclusion which did not reflect the Turkish population causing selection bias.     

Rhesus positivity and low high-density lipoprotein cholesterol: a new link?

The aim of the study was to investigate the relationship of ABO and Rh blood groups with lipid profile in patients with established multivessel coronary artery disease in a population with low levels of high-density lipoprotein cholesterol. The records of 978 patients with multivessel coronary artery disease, in whom coronary bypass surgery was performed, were investigated. Coronary risk factors including diabetes, hypertension, smoking, and obesity were noted for each patient. Serum lipid profiles: total cholesterol, low-density and high-density lipoprotein cholesterol, and triglyceride levels, were also recorded. The mean age of the patients was 59.3 +/- 9.7 years (range, 25-84 years) and 80% were male. The risk factors and lipid profiles of ABO blood types were similar. Rh-negative patients had higher levels of high-density lipoprotein cholesterol (46.9 +/- 9.9 vs. 41.6 +/- 10.4 mg.dL(-1), p = 0.001) and a lower total/high-density lipoprotein cholesterol ratio (4.8 +/- 1.3 vs. 5.2 +/- 1.6, p = 0.029) compared to Rh-positive patients. The other lipid levels and risk factors had no association with Rh typing. These results indicate a significant association between rhesus positivity and low levels of high-density lipoprotein cholesterol in patients with multivessel coronary artery disease.     

Is the decreased high-density lipoprotein cholesterol in the metabolic syndrome due to cellular lipid efflux defect?

The metabolic syndrome (MS) is associated with cardiovascular disease. The low high-density lipoprotein cholesterol (HDL-C) seen in the MS is associated with increased hepatic secretion of apolipoprotein B-containing lipoproteins. Patients with low HDL-C and abnormal cellular lipid efflux due to ABCA1 gene defects (Tangier disease) also have elevated plasma triglycerides. In the present study, we examined the cellular cholesterol and phospholipid efflux in patients with low HDL-C and features of the MS. Forty-four patients with a HDL-C below the fifth percentile for age and gender were selected. The MS was defined by a low HDL-C and at least two additional features: body mass index at least 30 kg/m(2), plasma triglycerides at least 150 mg/dl, fasting glucose at least 110 mg/dl, and blood pressure at least 130/85 mm Hg. Cellular lipid efflux was examined on fibroblasts obtained from study subjects, nine normal controls and six subjects with Tangier disease. In 22 patients identified with the MS, HDL-C was 21 +/- 7 mg/dl, triglyceride levels were 340 +/- 157 mg/dl, and cellular cholesterol and phospholipid efflux were 107 +/- 18% and 105 +/- 17% of controls, respectively. No patient with the MS and low HDL-C showed a cellular lipid efflux defect. We conclude that primary cellular lipid efflux defects do not contribute to the low HDL-C frequently encountered in the MS.     

Dialysis in 2011: Can cardiovascular risk in dialysis patients be decreased?

More than 1.4 million patients are on renal replacement therapy worldwide. Mortality in patients with end-stage renal disease (ESRD) is as high as that seen in some types of metastatic cancer, and premature cardiovascular disease is the major killer in ESRD. Several publications in 2011 addressed how interventions can modify cardiovascular risk factors and improve outcomes.     

At what levels of total low- or high-density lipoprotein cholesterol should diet/drug therapy be initiated? United States guidelines

Guidelines for the detection, evaluation and treatment of hypercholesterolemia in adults have been established in the United States. These guidelines recommend that total cholesterol levels be used for screening purposes. Total cholesterol levels greater than 240 mg/dl are considered "high," those from 200 to 239 mg/dl "borderline," and those less than 200 mg/dl "normal," regardless of the person's age or gender. All persons in the high category, as well as those in the borderline category who have other risk factors or established vascular disease, require measurements of low-density lipoprotein (LDL) cholesterol levels. LDL cholesterol levels are used to guide the selection of treatment. Patients with LDL cholesterol levels greater than 130 mg/dl are candidates for active diet therapy. Those whose LDL cholesterol levels are 160 to 190 mg/dl after 3 to 6 months of diet therapy are candidates for drug therapy. A high-density lipoprotein (HDL) level less than 35 mg/dl is considered a risk factor and may influence the level of LDL at which drug therapy is initiated. Some observers have expressed concern that these guidelines overemphasize LDL cholesterol at the expense of total cholesterol, HDL cholesterol and triglyceride levels. Nevertheless, the guidelines have been broadly accepted and currently serve as the basis for a widespread public-health education program.     

High-density lipoprotein cholesterol in the cardiovascular equation: does the "good" still count?

This article will discuss our current understanding of the role of HDL-C in the statin era, focusing on the question as to whether HDL-C still “counts” when determining cardiovascular risk. Epidemiologic evidence consistently demonstrates that low HDL-C is a strong and independent risk factor for CHD. The epidemiologic evidence is complimented by clinical data showing that interventions that raise HDL-C are associated with reductions in CHD risk, as well as by a growing body of experimental data demonstrating biologically plausible mechanisms that may underlie the observed clinical findings. Analyses of large statin trials also indicate that the significant and independent relationship between HDL-C and CHD risk persists despite the therapeutic effects of statins, and that HDL-C levels in statin-treated patients, both at baseline and in response to statin therapy, are relevant. Early studies on novel HDL targeting therapies are promising, but their long term safety profile and impact on clinical outcomes is yet to be determined in larger studies. Recent guidelines emphasize low HDL-C as an independent risk factor for cardiovascular disease, specifically identify HDL-C as a target for intervention, and encourage the use of HDL-C raising interventions in high-risk patients with low HDL-C levels.     

Can strategic and tactical compensation reduce crash risk in older drivers?

OBJECTIVE: to determine whether the use of strategic and tactical compensation can successfully improve safety in older drivers. METHODS: 84 healthy subjects aged between 65 and 96 were referred for a fitness-to-drive evaluation. Using ANOVA and contrast analysis, we tested the hypothesis that bad drivers who have had no car accidents use more active compensation strategies than bad drivers who have caused accidents in the previous 12 months. We classified drivers as bad, average or good, based on a structured road test. RESULTS: drivers who select driving tasks below their capacities and compensate by adapting their driving style cause fewer accidents than those who do not apply these strategies. CONCLUSIONS: fitness-to-drive screening procedures need a broader perspective to prevent an over-emphasis on procedures which focus more on deficit than on capacities.     

Effect of niacin on preβ-1 high-density lipoprotein levels in diabetes

Preβ-1 high-density lipoprotein (HDL) is an acceptor of peripheral free cholesterol and thus a participant in reverse cholesterol transport. Because patients with diabetes may have defects in reverse cholesterol transport, we hypothesized that (1) preβ-1 HDL might be decreased in diabetes and (2) because niacin improves reverse cholesterol transport and may stimulate preβ-1 HDL maturation, niacin would further decrease steady-state levels of preβ-1 HDL in diabetes. Absolute levels of preβ-1 HDL mass were measured using an isotopic dilution-ultrafiltration assay that measures apolipoprotein (apo) A-I after physically isolating preβ-1. Plasma apo A-I concentration and routine lipids were also evaluated in 11 diabetic patients. Diabetic subjects have a nearly 50% reduction of circulating levels of preβ-1 HDL to 36 ± 22 (1 SD) μg/mL compared with our previously published values of 73 ± 44 μg/mL in 136 healthy subjects. After niacin therapy, there was a further 17% reduction of preβ-1 HDL levels to 30 ± 26 μg/mL (P < .026) compared with baseline. The percentage of preβ-1 HDL in diabetic patients, as a percentage of total apo A-I, was about half of the normal value of 6.1% ± 3.6%; after niacin in diabetic patients, the percentage further decreased from 3.3% ± 2.1% to 2.3% ± 1.9% (P < .003). Absolute levels of apo A-I were similar in diabetic patients (1.14 ± 0.29) and healthy subjects (1.24 ± 0.24), and were unchanged by niacin in diabetic patients. We conclude with the novel observations that diabetes is associated with significantly reduced levels of preβ-1 HDL and that, after niacin treatment, a further lowering of preβ-1 HDL levels occur. Several altered mechanisms of RCT in diabetes are consistent with low levels of preβ-1 HDL both before and after niacin treatment.