Cholesterol, statins, and mortality

ArticleinThe Lancet 371(9619):1161; author reply 1162-3 · May 2008with 24 Reads
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  • Article
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    Background The development of atherosclerosis is strongly linked to disorders of cholesterol metabolism. Matrix metalloproteinases (MMPs) are dysregulated in patients and animal models with atherosclerosis. Whether systemic MMP activity influences cholesterol metabolism is unknown. Methods and Results We examined MMP‐9–deficient (Mmp9−/−) mice and found them to have abnormal lipid gene transcriptional responses to dietary cholesterol supplementation. As opposed to Mmp9+/+ (wild‐type) mice, Mmp9−/− mice failed to decrease the hepatic expression of sterol regulatory element binding protein 2 pathway genes, which control hepatic cholesterol biosynthesis and uptake. Furthermore, Mmp9−/− mice failed to increase the expression of genes encoding the rate‐limiting enzymes in biliary cholesterol excretion (eg, Cyp7a and Cyp27a). In contrast, MMP‐9 deficiency did not impair intestinal cholesterol absorption, as shown by the ¹⁴C‐cholesterol and ³H‐sitostanol absorption assay. Similar to our earlier study on Mmp2−/− mice, we observed that Mmp9−/− mice had elevated plasma secreted phospholipase A2 activity. Pharmacological inhibition of systemic circulating secreted phospholipase A2 activity (with varespladib) partially normalized the hepatic transcriptional responses to dietary cholesterol in Mmp9−/− mice. Functional studies with mice deficient in other MMPs suggested an important role for the MMP system, as a whole, in modulation of cholesterol metabolism. Conclusions Our results show that MMP‐9 modulates cholesterol metabolism, at least in part, through a novel MMP‐9–plasma secreted phospholipase A2 axis that affects the hepatic transcriptional responses to dietary cholesterol. Furthermore, the data suggest that dysregulation of the MMP system can result in metabolic disorder, which could lead to atherosclerosis and coronary heart disease.
  • Article
    “Polypill” describes a fixed dose combination pill containing several components designed to lower several cardiovascular risk factors simultaneously.1 For people who have had a cardiovascular disease event or related disorders such as angina pectoris, combination treatment has been practised for many years, although apart from the use of aspirin there has been a tendency to treat each risk factor rather than the overall risk of the disease. For example, until recently statins have been prescribed only if serum cholesterol is raised.2 3 4 Blood pressure lowering drugs are given only if a diagnosis of hypertension has been made.2 4 5 6 7 This is inappropriate and leads to many people not receiving preventive treatment who could benefit from receiving such treatment. The basis for preventing clinical cardiovascular disease with a combination of agents that reduce causal risk factors is that, within the range of values of these risk factors in the population, there is no threshold below which a reduction in risk factor ceases to confer a reduction in risk. Indeed, cohort (prospective observational) studies show that blood pressure and cholesterol exhibit a linear relation between the level of the risk factor and the risk of the disease when the risk of the disease is plotted on a proportional (that is, logarithmic) scale.8 9 10 11 12 This relation has great clinical significance, because it shows that for given changes in the risk factor there is a constant proportional change in the risk of disease. So, for example, a reduction of 1 mmol/l in low-density lipoprotein (LDL) cholesterol is associated with an approximate 40% reduction in the risk of having an ischaemic heart disease (IHD) event,13 and a 10 mm Hg decrease in diastolic blood pressure is associated with an approximate 60% decrease in risk of …
  • Article
    Statins (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors), cholesterol-lowering agents widely prescribed for cardiovascular health, have been shown to exert several pleiotropic effects. Although some studies reported that statins have no effects on malignancies of any kind, results of several epidemiologic and in vitro studies highlighted that statins exert anticancer activity in various cell types, showing that long-term therapy inhibits the incidence and/or progression of some human tumours. In particular, in the present overview we focused the attention on a neglected aspect of the pleiotropic functions of some lipophilic statins, suggesting that the possible mechanism of matrix metalloproteinase downregulation arises from prolonged lowering of circulating cholesterol. Our hypothesis may explain the literary findings about the phenomenon of switching of breast cancer phenotypes by statins, shedding the basis of future epidemiologic and basic science studies about the role of circulating and/or tumor-resident cholesterol in the initiation and progression of breast cancer.
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    Although statins reduce coronary and cerebrovascular morbidity and mortality in middle-aged individuals, their efficacy and safety in elderly people is not fully established. Our aim was to test the benefits of pravastatin treatment in an elderly cohort of men and women with, or at high risk of developing, cardiovascular disease and stroke. We did a randomised controlled trial in which we assigned 5804 men (n=2804) and women (n=3000) aged 70-82 years with a history of, or risk factors for, vascular disease to pravastatin (40 mg per day; n=2891) or placebo (n=2913). Baseline cholesterol concentrations ranged from 4.0 mmol/L to 9.0 mmol/L. Follow-up was 3.2 years on average and our primary endpoint was a composite of coronary death, non-fatal myocardial infarction, and fatal or non-fatal stroke. Analysis was by intention-to-treat. Pravastatin lowered LDL cholesterol concentrations by 34% and reduced the incidence of the primary endpoint to 408 events compared with 473 on placebo (hazard ratio 0.85, 95% CI 0.74-0.97, p=0.014). Coronary heart disease death and non-fatal myocardial infarction risk was also reduced (0.81, 0.69-0.94, p=0.006). Stroke risk was unaffected (1.03, 0.81-1.31, p=0.8), but the hazard ratio for transient ischaemic attack was 0.75 (0.55-1.00, p=0.051). New cancer diagnoses were more frequent on pravastatin than on placebo (1.25, 1.04-1.51, p=0.020). However, incorporation of this finding in a meta-analysis of all pravastatin and all statin trials showed no overall increase in risk. Mortality from coronary disease fell by 24% (p=0.043) in the pravastatin group. Pravastatin had no significant effect on cognitive function or disability. Pravastatin given for 3 years reduced the risk of coronary disease in elderly individuals. PROSPER therefore extends to elderly individuals the treatment strategy currently used in middle aged people.
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    To assess the impact of sex-specific patterns in cholesterol levels on all-cause and cardiovascular mortality in the Vorarlberg Health Monitoring and Promotion Programme (VHM&PP). In this study, 67413 men and 82237 women (aged 20-95 years) underwent 454448 standardized examinations, which included measures of blood pressure, height, weight, and fasting samples for cholesterol, triglycerides, gamma-glutamyl transferase (GGT), and glucose in the 15-year period 1985-1999. Relations between these variables and risk of death were analyzed using two approaches of multivariate analyses (Cox proportional hazard and GEE models). Patterns of cholesterol levels showed marked differences between men and women in relation to age and cause of death. The role of high cholesterol in predicting death from coronary heart disease could be confirmed in men of all ages and in women under the age of 50. In men, across the entire age range, although of borderline significance under the age of 50, and in women from the age of 50 onward only, low cholesterol was significantly associated with all-cause mortality, showing significant associations with death through cancer, liver diseases, and mental diseases. Triglycerides > 200 mg/dl had an effect in women 65 years and older but not in men. This large-scale population-based study clearly demonstrates the contrasting patterns of cholesterol level in relation to risk, particularly among those less well studied previously, that is, women of all ages and younger people of both sexes. For the first time, we demonstrate that the low cholesterol effect occurs even among younger respondents, contradicting the previous assessments among cohorts of older people that this is a proxy or marker for frailty occurring with age.
  • Article
    We sought to assess the relationship between the magnitude of low-density lipoprotein cholesterol (LDL-C) lowering and rates of elevated liver enzymes, rhabdomyolysis, and cancer. Although it is often assumed that statin-associated adverse events are proportional to LDL-C reduction, that assumption has not been validated. Adverse events reported in large prospective randomized statin trials were evaluated. The relationship between LDL-C reduction and rates of elevated liver enzymes, rhabdomyolysis, and cancer per 100,000 person-years was assessed using weighted univariate regression. In 23 statin treatment arms with 309,506 person-years of follow-up, there was no significant relationship between percent LDL-C lowering and rates of elevated liver enzymes (R2 <0.001, p = 0.91) or rhabdomyolysis (R2 = 0.05, p = 0.16). Similar results were obtained when absolute LDL-C reduction or achieved LDL-C levels were considered. In contrast, for any 10% LDL-C reduction, rates of elevated liver enzymes increased significantly with higher statin doses. Additional analyses demonstrated a significant inverse association between cancer incidence and achieved LDL-C levels (R2 = 0.43, p = 0.009), whereas no such association was demonstrated with percent LDL-C reduction (R2 = 0.09, p = 0.92) or absolute LDL-C reduction (R2 = 0.05, p = 0.23). Risk of statin-associated elevated liver enzymes or rhabdomyolysis is not related to the magnitude of LDL-C lowering. However, the risk of cancer is significantly associated with lower achieved LDL-C levels. These findings suggest that drug- and dose-specific effects are more important determinants of liver and muscle toxicity than magnitude of LDL-C lowering. Furthermore, the cardiovascular benefits of low achieved levels of LDL-C may in part be offset by an increased risk of cancer.
  • Article
    Age, sex, and blood pressure could modify the associations of total cholesterol (and its main two fractions, HDL and LDL cholesterol) with vascular mortality. This meta-analysis combined prospective studies of vascular mortality that recorded both blood pressure and total cholesterol at baseline, to determine the joint relevance of these two risk factors. Information was obtained from 61 prospective observational studies, mostly in western Europe or North America, consisting of almost 900,000 adults without previous disease and with baseline measurements of total cholesterol and blood pressure. During nearly 12 million person years at risk between the ages of 40 and 89 years, there were more than 55,000 vascular deaths (34,000 ischaemic heart disease [IHD], 12,000 stroke, 10,000 other). Information about HDL cholesterol was available for 150,000 participants, among whom there were 5000 vascular deaths (3000 IHD, 1000 stroke, 1000 other). Reported associations are with usual cholesterol levels (ie, corrected for the regression dilution bias). 1 mmol/L lower total cholesterol was associated with about a half (hazard ratio 0.44 [95% CI 0.42-0.48]), a third (0.66 [0.65-0.68]), and a sixth (0.83 [0.81-0.85]) lower IHD mortality in both sexes at ages 40-49, 50-69, and 70-89 years, respectively, throughout the main range of cholesterol in most developed countries, with no apparent threshold. The proportional risk reduction decreased with increasing blood pressure, since the absolute effects of cholesterol and blood pressure were approximately additive. Of various simple indices involving HDL cholesterol, the ratio total/HDL cholesterol was the strongest predictor of IHD mortality (40% more informative than non-HDL cholesterol and more than twice as informative as total cholesterol). Total cholesterol was weakly positively related to ischaemic and total stroke mortality in early middle age (40-59 years), but this finding could be largely or wholly accounted for by the association of cholesterol with blood pressure. Moreover, a positive relation was seen only in middle age and only in those with below-average blood pressure; at older ages (70-89 years) and, particularly, for those with systolic blood pressure over about 145 mm Hg, total cholesterol was negatively related to haemorrhagic and total stroke mortality. The results for other vascular mortality were intermediate between those for IHD and stroke. Total cholesterol was positively associated with IHD mortality in both middle and old age and at all blood pressure levels. The absence of an independent positive association of cholesterol with stroke mortality, especially at older ages or higher blood pressures, is unexplained, and invites further research. Nevertheless, there is conclusive evidence from randomised trials that statins substantially reduce not only coronary event rates but also total stroke rates in patients with a wide range of ages and blood pressures.
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