Statins for improving renal outcomes: a meta-analysis

Multiorgan-protective actions of blockers of the renin-angiotensin system, statins and erythropoietin: common pleiotropic effects in reno-, cardio- and neuroprotection

Renal diseases induce nephroprotective measures that may affect the heart, brain and other organs. In addition, many cardiovascular and neurological diseases are accompanied by renal lesions. For these reasons, multiorgan-protective measures, including cardio-, reno- and neuro-protective measures, are necessary to treat these diseases. The drugs used in nephrology are often pleiotropic. Although they usually address a single organ or tissue, many of them have complex actions that may provide multiorgan-protection. The present paper aims to review 3 classes of drugs that are commonly prescribed in nephrological practice: statins, RAS blockers (such as ACEIs and ARBs) and erythropoietin (EPO). This paper highlights the renoprotective actions, as well as those that are protective of the heart, brain and other organs, of these drugs at the cellular and molecular level. Their protective actions are attributable to their main effects and pleiotropic effects. The protective pleiotropic actions of these drugs may be exerted on multiple organs, making them multiorgan-protective. Another objective is to analyse the shared multiorgan-protective pleiotropic effects of RAS blockers (ACEIs and ARBs), statins and erythropoietin. This will allow for the practical association of the main renoprotective drugs with multiorgan protection.

Effect of statins on the development of renal dysfunction

Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) decrease serum cholesterol. Dyslipidemia is believed to be associated with the development of renal dysfunction. It was postulated that statins may reduce the development of renal dysfunction. The effect of statin use on the development of renal dysfunction in 197,551 patients (Department of Veterans Affairs, Veterans Integrated Service Network 16 [VISN16] database) was examined. Of these patients, 29.5% (58,332 patients) were statin users and 70.5% (139,219 patients) were not. Development of renal dysfunction was defined as doubling of baseline creatinine or increase in serum creatinine > or =0.5 mg/dl from the first to last measurement with a minimum of 90 days in between. During 3.1 years of follow-up, 3.4% of patients developed renal dysfunction. After adjustment for demographics, diabetes mellitus, smoking, hypertension, and other medications (mainly angiotensin-converting enzyme inhibitors, calcium channel blockers, and aspirin), use of statins decreased the odds of developing renal dysfunction by 13% (odds ratio [OR] 0.87, 95% confidence interval [CI] 0.82 to 0.92, p <0.0001). The beneficial effect of statins appeared to be independent of the decrease in cholesterol. Other variables that affected the development of renal dysfunction were age (OR 1.04, 95% CI 1.03 to 1.04, p <0.0001), diabetes (OR 1.77, 95% CI 1.68 to 1.86, p <0.0001), hypertension (OR 1.11, 95% CI 1.02 to 1.2, p = 0.0153), and smoking (OR 1.12, 95% CI 1.02 to 1.24, p = 0.0244). In conclusion, statin use may retard the development of renal dysfunction. The beneficial effect of statins in preventing the development of renal dysfunction appears to be independent of their lipid-lowering effect.

Lipid abnormalities and cardiovascular risk in renal disease

The recent 4D study failed to provide definitive evidence for benefit of statin use in type 2 diabetics on dialysis. This finding stands in stark contrast to a number of other observations in patients with early stages of chronic kidney disease where substantial benefit of statins had been documented. Here we discuss some potential explanations for the unexpected finding of the 4D study and for the negative association between below average total cholesterol and vascular mortality among dialysis patients. Admittedly, in the absence of definite evidence in dialysis patients, we still conclude that the administration of statins is appropriate in patients with manifest coronary disease.

Effects of statins in patients with chronic kidney disease: meta-analysis and meta-regression of randomised controlled trials

OBJECTIVE

To analyse the benefits and harms of statins in patients with chronic kidney disease (pre-dialysis, dialysis, and transplant populations).

DESIGN

Meta-analysis.

DATA SOURCES

Cochrane Central Register of Controlled Trials, Medline, Embase, and Renal Health Library (July 2006).

STUDY SELECTION

Randomised and quasi-randomised controlled trials of statins compared with placebo or other statins in chronic kidney disease.

DATA EXTRACTION AND ANALYSIS

Two reviewers independently assessed trials for inclusion, extracted data, and assessed trial quality. Differences were resolved by consensus. Treatment effects were summarised as relative risks or weighted mean differences with 95% confidence intervals by using a random effects model.

RESULTS

Fifty trials (30 144 patients) were included. Compared with placebo, statins significantly reduced total cholesterol (42 studies, 6390 patients; weighted mean difference -42.28 mg/dl (1.10 mmol/l), 95% confidence interval -47.25 to -37.32), low density lipoprotein cholesterol (39 studies, 6216 patients; -43.12 mg/dl (1.12 mmol/l), -47.85 to -38.40), and proteinuria (g/24 hours) (6 trials, 311 patients; -0.73 g/24 hour, -0.95 to -0.52) but did not improve glomerular filtration rate (11 studies, 548 patients; 1.48 ml/min (0.02 ml/s), -2.32 to 5.28). Fatal cardiovascular events (43 studies, 23 266 patients; relative risk 0.81, 0.73 to 0.90) and non-fatal cardiovascular events (8 studies, 22 863 patients; 0.78, 0.73 to 0.84) were reduced with statins, but statins had no significant effect on all cause mortality (44 studies, 23 665 patients; 0.92, 0.82 to 1.03). Meta-regression analysis showed that treatment effects did not vary significantly with stage of chronic kidney disease. The side effect profile of statins was similar to that of placebo. Most of the available studies were small and of suboptimal quality; mortality data were provided by a few large trials only.

CONCLUSION

Statins significantly reduce lipid concentrations and cardiovascular end points in patients with chronic kidney disease, irrespective of stage of disease, but no benefit on all cause mortality or the role of statins in primary prevention has been established. Reno-protective effects of statins are uncertain because of relatively sparse data and possible outcomes reporting bias.

Statins for people with kidney disease

Criteria for treatment should be the same as for people with normal kidney function

The Lipid lowering and Onset of Renal Disease (LORD) Trial: a randomized double blind placebo controlled trial assessing the effect of atorvastatin on the progression of kidney disease

Background

There is evidence that dyslipidemia is associated with chronic kidney disease (CKD). Experimental studies have established that lipids are damaging to the kidney and animal intervention studies show statins attenuate this damage. Small clinical trials, meta-analyses, observational studies and post-hoc analyses of cardiovascular intervention studies all support the concept that statins can reduce kidney damage in humans. Based on this background, a double blind randomized placebo controlled trial was designed to assess the effectiveness of atorvastatin 10 mg on slowing the progression of kidney disease in a population of patients with CKD.

Method/Design

The Lipid lowering and Onset of Renal Disease (LORD) trial is a three-year, single center, multi-site, double blind, randomized, placebo controlled trial. The primary outcome measure is kidney function measured by eGFR calculated by both Modification of Diet in Renal Disease (MDRD) and Cockcroft and Gault equations. Secondary outcome measures include kidney function measured by 24-hour urine creatinine clearance and also 24-hour urinary protein excretion, markers of oxidative stress, inflammation and drug safety and tolerability.

Discussion

The results of this study will help determine the effectiveness and safety of atorvastatin and establish its effects on oxidative stress and inflammation in patients with CKD.

Trial Registration

ANZCTRN012605000693628

Management of cardiovascular disease in renal transplant recipients

Cardiovascular disease is a major cause of graft loss and the leading cause of death in renal transplant recipients. Although there are robust data on the frequency of risk factors and their contributions to cardiovascular disease in this population, few trials have demonstrated the benefit of modifying these risk factors to reduce cardiovascular events. Nevertheless, it is widely accepted that the clinical acumen filtered through the best available studies in the general population be used to treat individual renal transplant recipients given their high cardiovascular mortality. Transplant task forces and the Kidney Disease Outcomes Quality Initiative have created guidelines for this purpose. This review examines the data available for prevention and treatment of major risk factors contributing to cardiovascular disease in renal transplant recipients. The contribution of immunosuppressive agents to each risk factor and the evidence to support lifestyle modification as well as drug therapy are examined. Reducing cardiovascular risk factors requires an integrative approach that is best accomplished by a team of health care professionals. It creates a significant challenge but one that must be met if allograft survival is to improve.

Targeting of RhoA/ROCK signaling ameliorates progression of diabetic nephropathy independent of glucose control

OBJECTIVE

RhoA, a small GTPase protein, and its immediate downstream target, Rho kinase (ROCK), control a wide variety of signal transduction pathways. Recent studies have shown that fasudil, a selective ROCK inhibitor, may play a pivotal role in a number of pathological conditions, ranging from cardiovascular diseases to pulmonary hypertension and erectile dysfunction. Considerable evidence suggests that some of the beneficial effects of statins may also stem from their modulatory effects on RhoA/ROCK signaling. In the current study, we hypothesized that pharmacological blockade of the RhoA/ROCK pathway with either fasudil or simvastatin would ameliorate progression of diabetic nephropathy.

RESEARCH DESIGN AND METHODS

In two separate experiments, diabetic db/db mice received fasudil (10 mg x kg(-) x day(-) i.p.) or simvastatin (40 mg x kg(-) x day(-) p.o.) for 16 weeks. Untreated db/db and db/m mice served as controls.

RESULTS

The kidney cortices of untreated db/db mice displayed increased ROCK activity compared with db/m mice. The fasudil-treated mice exhibited a significant reduction in ROCK activity, albuminuria, glomerular collagen IV accumulation, and urinary collagen IV excretion compared with untreated db/db mice. Interestingly, blood glucose was unaffected by fasudil administration. Treatment with simvastatin significantly attenuated RhoA activation in the kidney cortices of db/db mice and resulted in a significant reduction of albuminuria and mesangial matrix expansion.

CONCLUSIONS

Based on these results, we propose that RhoA/ROCK blockade constitutes a novel approach to the treatment of diabetic nephropathy. Our data also suggest a critical role for RhoA/ROCK activation in the pathogenesis of diabetic nephropathy.

Dyslipidaemia and cardiorenal disease: mechanisms, therapeutic opportunities and clinical trials

Dyslipidaemia is an important risk factor for the development of chronic kidney disease (CKD) and cardiovascular disease (CVD). CKD generates an atherogenic lipid profile, characterised by high triglycerides, low high-density lipoprotein (HDL) cholesterol and accumulation of small dense low-density lipoprotein (LDL) particles, comparable to that in the metabolic syndrome. These changes are due specifically to the effects of CKD on key enzymes, transfer proteins and receptors involved in lipid metabolism. Dyslipidaemia is further compounded by dialysis, immunosuppressive drugs, and concomitant diseases such as diabetes mellitus. Post hoc analyses from large intervention trials suggest the benefit of statins in patients with early CKD, but prospective clinical trials in haemodialysis (HD) and renal transplant recipients have not conclusively shown improvements in hard cardiovascular end-points. The lack of efficacy of statins in late-stage CKD could be a consequence of other disease processes, such as calcific arteriopathy and insulin resistance, which are not modified by lipid-lowering agents. Despite uncertainty and pending the results of ongoing statin trials such as Study of Heart and Renal Protection (SHARP) and AURORA (A study to evaluate the Use of Rosuvastatin in subjects On Regular haemodialysis: an Assessment of survival and cardiovascular events), major international guidelines continue to support statin therapy in CKD and renal transplant patients to reduce cardiovascular risk burden. Because of increased risk of toxicity, particularly myopathy, statins and other lipid-regulating agents should be used cautiously in CKD and renal transplant recipients.

Broken pump or leaky filter? Renal dysfunction in heart failure a contemporary review

Renal dysfunction is a frequent and progressive complication of chronic heart failure and is a powerful predictor of cardiovascular mortality. It is intimately associated with cardiovascular disease even in its earliest stages. Although cardiovascular and renal disease share many risk factors, the prognostic implications do not simply reflect widespread atherosclerotic vascular disease as this appears to be as important in those with heart failure secondary to idiopathic dilated cardiomyopathy as it is in those with coronary artery disease. There may be a role in the progression of heart failure, as the deleterious effects of even "mild" renal impairment seem to be borne out in predicting outcome, in a broad range of heart failure patients including those with heart failure and preserved systolic function. Renal dysfunction is both an indication for, as well as frequently limiting intervention with intensive disease modifying therapy. Although renal impairment is common in heart failure and these patients are at higher risk for adverse events including death, they are under represented in clinical trials.

Hyperbaric oxygen treatment augments the efficacy of cilazapril and simvastatin regimens in an experimental nephrotic syndrome model

BACKGROUND

Oxidative stress plays a role in the mechanism of chronic kidney disease (CKD), and antioxidant regimes are regarded as promising treatment modalities. We compared the effects of cilazapril, simvastatin, and hyperbaric oxygen (HBO) treatment on proteinuria and on oxidative stress in adriamycine (ADR)-induced proteinuria.

METHODS

Seventy male Sprague-Dawley rats were housed, and 60 were injected with ADR to induce nephrosis. After the stabilization of proteinuria, rats were treated for 6 weeks with simvastatin (n = 10, 4 mg/kg/day), cilazapril (n = 10, 10 mg/kg/day), HBO (n = 10, 2.8 athmosphere absolute, 90 min/daily), HBO + cilazapril (n = 10), HBO + simvastatin (n = 10), and vehicle (n = 10). After euthanization at 12 weeks, protein carbonyl (PCO), superoxide dismutase (SOD), and glutathion peroxidase (GPx) levels were analyzed from tissues. The histological alterations in the kidneys were determined by semiquantitative scoring.

RESULTS

Protein carbonyl (PCO) levels were higher (p < 0.001), and the GPx and SOD levels were lower (p < 0.001 for all) in the nephrotic rats. Proteinuria was correlated to PCO (r = 0.483), GPx (r = -0.686), or SOD (r = -0.620) (p < 0.001 for all). Superoxide dismutase (SOD) (beta = -0.381, p = 0.02) and GPx (beta = -0.509, p < 0.001) were independently related to proteinuria levels. Both cilazapril and simvastatin significantly improved GPx, SOD, PCO, and proteinuria. When HBO was combined with either drug, the above markers further improved (p < 0.001). Both regimens caused distinct histological features, while the combination of HBO made much significant histological improvement.

CONCLUSION

Both cilazapril and simvastatin regimens improve oxidative stress and proteinuria, while the effects significantly increase with the combination of HBO treatment. HBO seems to be a candidate antioxidant strategy in glomerular diseases.

Effects of lipid-lowering therapy with rosuvastatin on atherosclerotic burden in patients with chronic kidney disease

OBJECTIVE

Although previous studies suggest that treatment of dyslipidemia with statins reduces mortality and morbidity that are associated with cardiovascular disease, only a few studies have examined the efficacy of statins on atherosclerotic status in patients with chronic kidney disease (CKD).

MATERIALS AND METHODS

A 12-month, prospective, randomized study was designed to assess the efficacy of rosuvastatin in reducing circulating atherosclerotic parameters and renal function in patients with CKD. Thirty-eight patients with CKD and LDL cholesterol levels > or =100 mg/dL were randomly assigned to receive 2.5 mg/dL rosuvastatin (group A, n=22) or nonrosuavastatin therapy (group B, n=16). Lipid profile, estimated glomerular filtration rate (eGFR), high sensitivity C-reactive protein (hs-CRP), and intima-media thickness (IMT) were measured before and 12 months after rosuvastatin was added to the treatment.

RESULTS

Total cholesterol, low-density lipoprotein cholesterol, remnant-like particle-cholesterol and triglycerides were significantly reduced only in patients who received rosuvastatin. These parameters remained unchanged in patients who were not treated with rosuvastatin. eGFR was significantly increased from 50.7+/-18.7 mL/min/1.73 m(2) to 53.3+/-20.1 mL/min/1.73 m(2) and a significant reduction of U-P was detected in group A patients (0.17+/-0.29 vs. 0.13+/-0.3 g/day; p<0.01). In addition to the hypolipidemic effect, rosuvastatin treatment significantly reduced hs-CRP (p=0.0054). Moreover, maximal IMT at the baseline (1.89+/-0.98 mm) decreased significantly to 1.75+/-0.87 mm at 12 months (p=0.0231).

CONCLUSION

Rosuvastatin treatment, in addition to its beneficial effect on cholesterol levels, reduced maximal IMT and modified the inflammatory state of these patients.

Lovastatin inhibits oxidized low-density lipoprotein-induced plasminogen activator inhibitor and transforming growth factor-beta1 expression via a decrease in Ras/extracellular signal-regulated kinase activity in mesangial cells

Oxidized low-density lipoprotein (Ox-LDL) might be involved in the progression of renal disease. Ox-LDL stimulation of plasminogen activator inhibitor-1 (PAI-1) expression via transforming growth factor-beta (TGF-beta)/Smad signaling in mesangial cells required activation of extracellular signal-regulated kinase (ERK). Mevalonate depletion by 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors, or statins, decreases the levels of farnesyl pyrophosphate (FPP) for isoprenylation of Ras. We postulate that statins may ameliorate the Ox-LDL-induced mesangial matrix accumulation by inhibiting Ras/ERK activation with subsequent downregulation of TGF-beta target genes. Quiescent mesangial cells were incubated for 18 h with and without the presence of lovastatin before 50 microg/mL of Ox-LDL treatment for 1 h. Lovastatin inhibited markedly the stimulatory effects of Ox-LDL on ERK1/2 activation, nuclear Smad3 expression, TGF-beta1 and PAI-1 mRNA and protein expression, and PAI-1 luciferase activity. These inhibitory effects of lovastatin were reversed almost completely by mevalonate or FPP. Similar to lovastatin, FTI-277, which is an inhibitor of Ras farnesylation, decreased the Ox-LDL-induced activation of ERK/Smad3 and induction of TGF-beta1/PAI-1. These results indicate that lovastatin prevents the Ox-LDL-induced Ras/ERK activation that results in inhibition of Smad3 activation in mesangial cells with subsequent downregulation of TGF-beta target genes. Thus, statins seem to have antifibrotic effects through their anti-TGF-beta response that are relevant in the treatment of chronic renal disease with dyslipidemia.

Lipid changes and statins in chronic renal insufficiency

It has been known for a long time that chronic kidney disease (CKD) is associated with dyslipidemia, but the full extent of abnormalities has been appreciated only recently, because routine laboratory tests fail to disclose the entire spectrum of lipid abnormalities. Lipids, particularly HDL cholesterol, are predictive of cardiovascular events, but a paradoxic inverse relation between cholesterol concentration and cardiovascular death has been noted in uremic patients. This currently is thought to be explained by the confounding effect of microinflammation and possibly calcification, but this is not definitely proved. Several retrospective analyses that included patients with mild or moderate CKD documented benefit from lowering of cholesterol by statins. In contrast, the Die Deutsche Diabetes Dialyse (4D) study and a small Scandinavian study failed to show a benefit from lowering of cholesterol by statins in ESRD. Pathomechanistically, it is possible that nonclassical pathomechanisms override statin-sensitive mechanisms as also suggested by the observation that statins fail to reduce carotid intima-media thickening. Although, experimentally, exposure to lipids (particularly oxidized lipids) aggravates progression, data on the effect of statins on progression in patients with CKD are not definite. The most likely explanation is that the impact of numerous confounders obscures their effect on progression. The increase in urinary protein excretion of patients who are treated with statins had been a cause of concern, but the underlying mechanism (i.e. interference with proximal tubular reabsorption of protein) meanwhile has been well documented.

The safety of statins in clinical practice

Statins are effective cholesterol-lowering drugs that reduce the risk of cardiovascular disease events (heart attacks, strokes, and the need for arterial revascularisation). Adverse effects from some statins on muscle, such as myopathy and rhabdomyolysis, are rare at standard doses, and on the liver, in increasing levels of transaminases, are unusual. Myopathy--muscle pain or weakness with blood creatine kinase levels more than ten times the upper limit of the normal range--typically occurs in fewer than one in 10,000 patients on standard statin doses. However, this risk varies between statins, and increases with use of higher doses and interacting drugs. Rhabdomyolysis is a rarer and more severe form of myopathy, with myoglobin release into the circulation and risk of renal failure. Stopping statin use reverses these side-effects, usually leading to a full recovery. Asymptomatic increases in concentrations of liver transaminases are recorded with all statins, but are not clearly associated with an increased risk of liver disease. For most people, statins are safe and well-tolerated, and their widespread use has the potential to have a major effect on the global burden of cardiovascular disease.

Effects of statins on renal function

Patients with chronic kidney disease (CKD) are much more likely to die of cardiovascular disease than end-stage renal disease. Dyslipidemia is highly prevalent in patients with CKD and may contribute to the elevated cardiovascular risk as well as CKD progression. Statins are lipid-lowering drugs that appear to protect the kidneys via cholesterol reduction as well as noncholesterol-mediated mechanisms. Subgroup analyses of major clinical studies and meta-analyses of smaller trials indicate that statin therapy slows the decline of the glomerular filtration rate. Additionally, statins appear to reduce proteinuria in patients with CKD. Statins are well recognized to reduce cardiovascular morbidity and mortality in patients with and without documented cardiovascular disease and in certain high-risk populations, such as persons with diabetes mellitus. However, conclusive evidence for improved cardiovascular outcomes with statin therapy for CKD is not yet available. Several ongoing studies are evaluating the effect of statins on cardiovascular end points in patients with CKD and may provide data needed to support adjunctive use of these agents in this high-risk population.

Preventing cardiovascular and renal complications in the management of hypertension and metabolic syndrome

This editorial discusses the history, definition and prevelance of the metabolic syndrome. Pathophysiological factors, such as girth, blood pressure, glucose, triglycerides, HDL-cholesterol, obesity, raised levels of plasma insulin and insulin resistance are outlined as being components of the syndrome. The paper examines the relationship of cardiovascular and all-cause mortality to the metabolic syndrome, and discusses the risk of cardiovascular disease associated with the metabolic syndrome. In addition, the article explores the link between metabolic syndrome, kidney function, insulin resistance and chronic kidney disease. Finally, the article discusses the issue of managing metabolic syndrome.

Racial and survival paradoxes in chronic kidney disease

Most of the 20 million people in the US with chronic kidney disease (CKD) die before commencing dialysis. One of every five dialysis patients dies each year in the US. Although cardiovascular disease is the most common cause of death among patients with CKD, conventional cardiovascular risk factors such as hypercholesterolemia, hypertension and obesity are paradoxically associated with better survival in hemodialysis populations. Emerging data indicate the existence of this 'reverse epidemiology' in earlier stages of CKD. There are also paradoxical relationships between outcomes and race and ethnicity. For example, the survival rate of African American dialysis patients seems to be superior to that of whites on dialysis. Paradoxes-within-paradoxes have been detected among Hispanic and Asian American CKD patients. These survival paradoxes might evolve and change over the natural course of CKD progression as a result of the time differentials of competing risk factors and the overwhelming impact of malnutrition, inflammation and wasting. Reversal of the reverse epidemiology as a result of successful kidney transplantation underscores the role of nutritional status and kidney function in engendering these paradoxes. The observation of paradoxes and their reversal might lead to the formulation of new paradigms and management strategies to improve the survival of patients with CKD. Such movement away from the use of targets set on the basis of data gathered in general populations (e.g. the Framingham cohort) would be a major paradigm shift in clinical medicine and public health.

Renoprotective effect of preoperative statins in coronary artery bypass grafting

The renoprotective effect of preoperative statin use in coronary artery bypass grafting remains poorly defined. A retrospective review of 1,802 consecutive patients who underwent isolated coronary artery bypass grafting from January 2002 to October 2005 was performed. Of those, 1,039 patients were receiving statins preoperatively, and 763 patients were not. Two propensity score-matched cohorts each of 641 patients (statin and nonstatin groups) were constructed. Multivariate logistic regression analyses for matched patients and all patients were performed to investigate whether preoperative statin use was associated with the incidence of new renal insufficiency. In a matched analysis, the statin group had a lower incidence of new renal insufficiency than the nonstatin group (1.6% vs 3.9%, odds ratio 0.39, 95% confidential interval 0.18 to 0.82, p = 0.01). Multivariate logistic regression analysis including all patients also showed that preoperative statin use (odds ratio 0.54, 95% confidence interval 0.30 to 0.99, p = 0.047) was significantly associated with low incidence of new postoperative renal insufficiency. In conclusion, preoperative statin use may be renoprotective after coronary artery bypass grafting.

Lipoprotein metabolism in chronic renal insufficiency

Chronic renal insufficiency (CRI) is associated with a characteristic dyslipidemia. Findings in children with CRI largely parallel those in adults. Moderate hypertriglyceridemia, increased triglyceride-rich lipoproteins (TRL) and reduced high-density lipoproteins (HDL) are the most usual findings, whereas total and low-density lipoprotein cholesterol (LDL-C) remain normal or modestly increased. Qualitative abnormalities in lipoproteins are common, including small dense LDL, oxidized LDL, and cholesterol-enriched TRL. Measures of lipoprotein lipase and hepatic lipase activity are reduced, and concentrations of apolipoprotein C-III are markedly elevated. Still an active area of research, major pathophysiological mechanisms leading to the dyslipidemia of CRI include insulin resistance and nonnephrotic proteinuria. Sources of variability in the severity of this dyslipidemia include the degree of renal impairment and the modality of dialysis. The benefits of maintaining normal body weight and physical activity extend to those with CRI. In addition to multiple hypolipidemic pharmaceuticals, fish oils are also effective as a triglyceride-lowering agent, and the phosphorous binding agent sevelamer also lowers LDL-C. Emerging classes of hypolipidemic agents and drugs affecting sensitivity to insulin may impact future treatment. Unfortunately, cardiovascular benefit has not been convincingly demonstrated by any trial designed to study adults or children with renal disease. Therefore, it is not possible at this time to endorse general recommendations for the use of any agent to treat dyslipidemia in children with chronic kidney disease.

[Strategies to slow the progression of chronic kidney disease]

High blood pressure and proteinuria are the major factors that drive progression of chronic kidney disease. Target levels for preserving renal function are blood pressure less than 130/80 mmHg and proteinuria less than 0.5 g/day. Angiotensin II converting enzyme inhibitors and sartans should be used as first-line therapy to reach these targets. Their use requires close monitoring of renal function and serum potassium levels. Moderate sodium restriction, possibly combined with diuretic therapy, helps to maximize the effect of renin-angiotensin inhibitors. Patients with chronic kidney disease have a high risk of acute kidney failure, especially due to drugs. All prescriptions must take into account the existence and extent of kidney disease. Patient adhesion and collaboration between health professionals are required if these measures are to be effective in the long term.

Chronic kidney disease: effects on the cardiovascular system

Accelerated cardiovascular disease is a frequent complication of renal disease. Chronic kidney disease promotes hypertension and dyslipidemia, which in turn can contribute to the progression of renal failure. Furthermore, diabetic nephropathy is the leading cause of renal failure in developed countries. Together, hypertension, dyslipidemia, and diabetes are major risk factors for the development of endothelial dysfunction and progression of atherosclerosis. Inflammatory mediators are often elevated and the renin-angiotensin system is frequently activated in chronic kidney disease, which likely contributes through enhanced production of reactive oxygen species to the accelerated atherosclerosis observed in chronic kidney disease. Promoters of calcification are increased and inhibitors of calcification are reduced, which favors metastatic vascular calcification, an important participant in vascular injury associated with end-stage renal disease. Accelerated atherosclerosis will then lead to increased prevalence of coronary artery disease, heart failure, stroke, and peripheral arterial disease. Consequently, subjects with chronic renal failure are exposed to increased morbidity and mortality as a result of cardiovascular events. Prevention and treatment of cardiovascular disease are major considerations in the management of individuals with chronic kidney disease.

Albumin transport and processing by the proximal tubule: physiology and pathophysiology

PURPOSE OF REVIEW

Significant epidemiological and clinical trial evidence supports the association between increased urinary albumin excretion, cardiovascular events and renal failure. An increase in albumin excretion has traditionally been considered to reflect a 'glomerular' leak of protein; however, it is now recognized that significant tubular reabsorption of albumin occurs under physiological conditions that may be modified by genetic determinants, systemic disease and drug therapies.

RECENT FINDINGS

The endocytosis of albumin by the proximal tubule is a highly regulated process depending on protein-protein interactions between several membrane proteins and scaffolding and regulatory molecules. The elucidation of these interactions is an ongoing research focus. There is also mounting evidence for a transcytotic pathway for retrieval of albumin from the tubular filtrate. The molecular basis for the role of albuminuria in both interstitial renal disease and cardiovascular pathology continues to be defined. The clinical implications of albuminuria due to a glomerular leak vs. reduced tubular reabsorption of albumin are, however, now under consideration. In particular, the prognostic implication of microalbuminuria induced by the more potent 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors is under study.

SUMMARY

The currently defined mechanisms underpinning the tubular reabsorption of albumin, how these are modified by pathology and pharmacology, and the clinical implications are the subject of this review.

Lower progression rate of end-stage renal disease in patients with peripheral arterial disease using statins or Angiotensin-converting enzyme inhibitors

Patients with peripheral arterial disease (PAD) are at increased risk for ESRD and cardiovascular events. The primary objective was to assess the association between ankle-brachial index (ABI) values and renal outcome. The secondary objective was to evaluate whether statins and angiotensin-converting enzyme inhibitors (ACEI) are associated with improved renal and cardiovascular outcome in patients with PAD. In a prospective observational cohort study of 1940 consecutive patients with PAD, ABI was measured and chronic statin and ACEI therapy was noted at baseline. Serial creatinine concentrations were obtained at baseline, 6 mo, and every year after enrollment. End points were ESRD, all-cause mortality, and cardiac events during a median follow-up period of 8 yr. Baseline estimated GFR <60 ml/min per 1.73 m(2) was assessed in 27% of patients. ESRD, all-cause mortality, and cardiac events occurred in 10, 46, and 31% of patients, respectively. In multivariate analysis, a lower baseline ABI was significantly associated with a higher progression rate of ESRD (hazard ratio [HR] per 0.10 decrease 1.34; 95% confidence interval [CI] 1.21 to 1.49). Chronic use of statins and ACEI were significantly associated with lower ESRD (HR 0.41 [95% CI 0.28 to 0.63] and 0.74 [95% CI 0.54 to 0.98], respectively), mortality (HR 0.66; [95% CI 0.55 to 0.82] and 0.84 [95% CI 78 to 0.95], respectively), and cardiac events (HR 0.71 [95% CI 0.56 to 0.91] and 0.81 [95% CI 0.68 to 0.96], respectively). In patients with PAD, low ABI values independently predict the onset of ESRD. Less progression toward ESRD and improved cardiovascular outcome was observed among patients who were on long-term statins and ACEI.

The effect of intensified lipid-lowering therapy on long-term prognosis in patients with peripheral arterial disease

BACKGROUND

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are associated with improved outcome in patients with peripheral arterial disease. Statins may also have beneficial properties beyond their lipid-lowering effect.

METHODS

A prospective, observational cohort study was conducted at a university hospital from 1990 to 2005 to examine whether higher doses of statins and lower low-density lipoprotein (LDL) cholesterol levels are both independently associated with improved outcome in peripheral arterial disease. Enrolled were 1374 consecutive patients (age, 61 +/- 10 years, 73% male) with peripheral arterial disease (ankle-brachial index <or=0.90). They were screened for clinical risk factors, statin therapy, and LDL cholesterol levels. Serial LDL cholesterol levels were measured at 6 months and yearly after enrollment. The mean follow-up time was 6.4 +/- 3.6 years, and no patients were lost to follow-up. The primary end points were all-cause and cardiac mortality. The secondary end point was the progression to kidney failure.

RESULTS

Overall mortality, cardiac death, and progression to kidney failure occurred in 29%, 20%, and 5% of patients, respectively. Multivariate analysis revealed that higher doses of statins (per 10% increase) and lower 6-month LDL cholesterol levels (per 10 mg/dL decrease) were both independently associated with lower all-cause mortality (hazard ratio [HR], 0.71; 95% confidence interval [CI], 0.62 to 0.80; and HR, 0.96; 95% CI, 0.93 to 0.98, respectively) and cardiac death (HR, 0.76; 95% CI, 0.67 to 0.86; and HR, 0.95; 95% CI, 0.92 to 0.98, respectively). Higher high-density lipoprotein cholesterol levels also correlated significantly with lower all-cause and cardiac mortality. Higher doses of statins (per 10% increase) were associated with less progression to kidney failure (HR, 0.69; 95% CI, 0.54 to 0.89).

CONCLUSIONS

Higher doses of statins and lower LDL cholesterol levels are both independently associated with improved outcome in patients with peripheral arterial disease. These results support the view that statins have beneficial effects beyond their lipid-lowering properties and should be considered in all patients with PAD, irrespective of LDL cholesterol levels.

Clinical trials in nephrology: success or failure

PURPOSE OF REVIEW

A large amount of clinical and epidemiologic evidence has been gathered supporting the importance of blood pressure control in reducing chronic kidney disease progression. Suppression of the rennin-angiotensin-aldosterone system should also be considered in any patient with chronic kidney disease, in particular if albuminuria is present.

RECENT FINDINGS

Analysis of renal outcome by estimating glomerular filtration rate in trials primarily devoted to cardiovascular protection in hypertensive patients, in particular the Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial trial, has come to question the effectiveness of suppressing the rennin-angiotensin-aldosterone system in controlling blood pressure and thus protecting the kidney in hypertensive patients. This subject is particularly interesting because the existence of an increased cardiovascular risk associated with renal function decline has been demonstrated in many different clinical conditions including arterial hypertension. The increase in global cardiovascular risk accompanying chronic kidney disease would necessitate the use of drugs suppressing the rennin-angiotensin-aldosterone system for cardiovascular protection irrespective of the influence on renal outcome.

SUMMARY

This review includes the most recent data evaluating renal endpoints in clinical trials primarily devoted to renal function as well as those dedicated to arterial hypertension and its cardiovascular consequences.

Nefropatia diabética e doença cardíaca

Pacientes em diferentes estágios de nefropatia diabética (ND) apresentam freqüentemente comprometimento cardíaco expresso por isquemia miocárdica e/ou cardiomiopatia diabética. Estas alterações já estão presentes em estágios iniciais da ND e provavelmente mesmo antes de a excreção urinária de albumina (EUA) atingir níveis tradicionalmente diagnósticos de microalbuminúria. As alterações cardíacas são responsáveis por uma proporção significativa de mortes nos pacientes com ND e podem ser reduzidas através de intervenção nos múltiplos fatores de risco cardiovascular encontrados nesses pacientes. A avaliação de doença cardíaca deve idealmente ser realizada em todos os pacientes com qualquer grau de ND através de métodos específicos para detectar isquemia e disfunção miocárdica, além do emprego rotineiro da monitorização ambulatorial da pressão arterial em 24 h. Em pacientes com aterosclerose avançada também devem ser avaliadas outras artérias (carótidas, aorta, renais). O tratamento rigoroso da hipertensão arterial, o uso de fármacos cardioprotetores, o tratamento da dislipidemia e da anemia, assim como o emprego de medicamentos anti-plaquetários, poderão reduzir a elevada mortalidade cardiovascular na ND.

The effect of statins on preservation of kidney function in patients with coronary artery disease

PURPOSE OF REVIEW

This paper outlines evidence for the putative renal benefits of statins in people with vascular disease.

RECENT FINDINGS

The Greek Atorvastatin and Coronary Heart Disease study showed a modest improvement in kidney function over 4 years among 800 atorvastatin recipients (12%), significantly better than the decrease in kidney function (4%) in 800 placebo recipients. A secondary analysis of the Cholesterol and Recurrent Events trial suggested that pravastatin reduced the rate of kidney function loss to a greater extent in participants with dipstick-positive proteinuria (P < 0.001) and lower levels of renal function at baseline (P = 0.04). A larger post-hoc analysis from this group found that pravastatin modestly reduced the risk of acute renal failure (RR 0.60, 95% CI 0.41-0.86), but not the risk of a 25% decline in kidney function from baseline (RR 0.94, 95% CI 0.88-1.01). In the group with lower baseline kidney function (glomerular filtration rate <60 ml/min/1.73 m(2)) and proteinuria on dipstick urinalysis (n = 249), pravastatin recipients were less likely to experience a 25% or greater decrease in glomerular filtration rate (12.5% versus 19.9%) or acute renal failure (3.2% versus 8.7%).

SUMMARY

Statins may reduce the rate of kidney function loss in people with cardiovascular disease, although the clinical significance of this effect is unclear. Future studies are required before statins can be recommended solely to protect renal function.

Preventing microalbuminuria in patients with type 2 diabetes

The public health burden of type 2 diabetes mellitus has been dramatically increasing world-wide. The chronic complications of type 2 diabetes play an important role in decreasing life expectancy and adversely affecting quality of life. Diabetic nephropathy, which is originally microvascular in nature, is widely considered an important complication of diabetes. In prospective clinical investigations, increased urinary albumin excretion proved to be associated not only with subsequent renal outcomes but also with cardiovascular morbidity/mortality independently of other risk factors. Therefore, microalbuminuria as an early sign of increased urinary albumin excretion should be considered important for both treatment and even for prevention. Preventing microalbuminuria might diminish progression to overt nephropathy and, hopefully, might limit cardiovascular events. Regarding primary prevention of diabetic nephropathy, therapeutic intervention should optimally be initiated at the stage of normoalbuminuria. Although additional factors such as smoking cessation, reduction of protein intake, and treatment of lipid abnormalities are important, providing optimal diabetic control as well as targeting optimal blood pressure are the key elements of a prevention strategy in diabetic patients. Recently, the Bergamo Nephrologic Diabetes Complications Trial (BENEDICT) documented that a significant decrease of the development of persistent microalbuminuria could be achieved by using an ACE-inhibitor, trandolapril alone or in combination with verapamil SR, a non-dihydropyridine calcium-channel blocker in hypertensive type 2 diabetic patients with normoalbuminuria. The results of this primary-prevention strategy should be corroborated by further investigations to determine whether these beneficial changes could later result in improvement of renal clinical outcomes, macrovascular complications, or both.

The dyslipidemia of chronic renal disease: effects of statin therapy

PURPOSE OF REVIEW

Dyslipidemia is a prevalent condition in patients with chronic renal disease, but is often left untreated. Statin treatment constitutes an effective way to improve lipid abnormalities. This review summarizes present studies on dyslipidemia and its treatment in patients with chronic renal disease.

RECENT FINDINGS

The specific dyslipidemia in renal disease is associated with the presence of proteinuria and decreased creatinine clearance, and may even adversely affect the progression of chronic renal disease. Statin therapy may have renoprotective effects due to a combination of lipid lowering and pleiotropic effects. Statins exert several anti-inflammatory properties and lead to a decrease of proteinuria. Post-hoc analyses of large-scale lipid lowering trials have shown that the reduction of cardiovascular risk was equivalent to the reduction achieved in patients without chronic renal failure. We feel, however, that if intervention with statins is postponed until patients reach end-stage renal disease, statins have limited benefit.

SUMMARY

Present studies suggest that patients with renal disease should be screened early for dyslipidemia and that statins have to be considered as the lipid lowering therapy of choice. These drugs reduce cardiovascular risk. Further studies are needed to firmly establish whether statins preserve renal function.

A Primer on the Design, Conduct, and Interpretation of Clinical Trials

Clinical trials are an especially powerful study design that often guides health care policy and clinical practice. Indeed, well-designed and rigorously conducted trials can establish the etiologic relevance of modifiable risk factors and the benefits (and risks) of candidate therapies. Contemporary schema that classify evidence place results from randomized trials at the pinnacle of evidence. The primary objective of this article is to provide an overview of the design, conduct, and interpretation of trials with an emphasis on aspects that are relevant to nephrology.