Should we reduce blood cholesterol to prevent cardiovascular disease among patients with chronic renal failure?

Sevelamer Hydrochloride versus Aluminum Hydroxide: Effect on Serum Phosphorus and Lipids in CAPD Patients

Background

Dietary phosphorus restriction, oral administration of phosphorus binders, and dialysis are the main strategies to control hyperphosphatemia in patients with stage 5 chronic kidney disease. Aluminum hydroxide (AH) and calcium carbonate, the most commonly used phosphorus binders, have serious disadvantages, such as aluminum toxicity and hypercalcemia. Sevelamer hydrochloride (SH) is a relatively new nonabsorbed calcium- and aluminum-free phosphorus binder. The present study was designed to evaluate the efficacy of SH in the control of hyperphosphatemia and its effect, compared to AH, on serum lipid parameters in patients on continuous ambulatory peritoneal dialysis (CAPD).

Methods

30 stable patients on CAPD were included in an open-label, randomized crossover study. After a 2-week phosphorus binder washout period, 15 patients (group I) were administered SH for 8 weeks and in the remaining patients (group II), AH was introduced (phase A). After a new 2-week washout period, patients crossed over to the alternate agent for another 8 weeks (phase B).

Results

There were similar reductions in serum phosphorus levels over the course of the study with both agents: by 1.18 ± 0.07 mg/dL (0.38 ± 0.03 mmol/L) with SH and by 1.25 ± 0.15 mg/dL (0.40 ± 0.05 mmol/L) with AH in phase A ( p = NS), and by 1.35 ± 0.25 mg/dL (0.43 ± 0.08 mmol/L) with AH and by 1.23 ± 0.80 mg/dL (0.39 ± 0.25 mmol/L) with SH in phase B ( p = NS). Moreover, SH administration was associated with a 10.5% ± 9.4% and a 20.1% ± 6.8% fall in total cholesterol ( p < 0.05) and low-density lipoprotein cholesterol ( p < 0.001) in phase A, and 11.9% ± 7.2% ( p < 0.05) and 21.5% ± 2.4% ( p < 0.001), respectively, in phase B. In both phases of the study, AH administration was not followed by a significant change in serum lipid parameters.

Conclusion

Sevelamer hydrochloride is a well-tolerated alternative to calcium- or aluminum-containing phosphorus binder in the control of serum phosphorus in CAPD patients. Furthermore, SH improves the lipid profile in these patients.

Threshold level of low-density lipoprotein cholesterol for the short-term benefit of statin therapy in the acute phase of myocardial infarction

BACKGROUND

Little is known about the threshold level of low-density lipoprotein cholesterol (LDL-C) for statin therapy in acute myocardial infarction (AMI).

HYPOTHESIS

The aim of this study was to investigate the short-term benefit of the statin in post-MI patients with low LDL-C levels.

METHODS

Between November 2005 and January 2008, 6866 statin-naive patients were selected from the Korea AMI registry. Major adverse cardiac event (MACE) was defined as a composite of death, recurrent MI, and revascularizations.

RESULTS

The 6-month MACE and mortality showed a U-shaped curve, with the lowest rate at 114-122 mg/dL. Propensity scores for statin use were calculated for patients with LDL-C ≤ 113 mg/dL, and they were used to match the patients who received statin (statin user, n = 1031) with those who did not receive it (statin nonuser, n = 1031). The 6-month MACE was not significantly different between statin users and statin nonusers (9.4% vs 11.0%; hazard ratio [HR]: 0.847, 95% confidence interval [CI]: 0.646-1.111, P = 0.230), whereas the 6-month mortality was significantly lower in statin users (7.2% vs 9.7%; HR: 0.728, 95% CI: 0.539-0.984, P = 0.039). However, when the analyses were repeated in the patients with LDL-C ≤ 105 mg/dL, not only the 6-month MACE (9.5% vs 9.9%; HR: 0.945, 95% CI: 0.700-1.277, P = 0.713) but also the 6-month mortality (7.0% vs 8.7%; HR: 0.793, 95% CI: 0.566-1.111, P = 0.177) was not significantly different between statin users and statin nonusers (n = 876 in each group).

CONCLUSIONS

The beneficial effects of statin therapy seem to vanish when LDL-C is below a certain level in AMI patients.

Acute Effect of Heparin on Lipid Parameters in Patients on Renal Replacement Therapy

Dialyzer membrane and the type of heparin used can influence lipid parameters. However, there are limited and debatable data concerning lipid alterations during a single hemodialysis session. Moreover, the role of hemoconcentration after every hemodialysis session confuses the real effect of the heparin on lipid profile. We investigated the acute effect of heparin administration on lipids in hemodialysis patients, but on an off-hemodialysis day in order to eliminate any effect of ultrafiltration. We studied six patients on hemodialysis, six patients on peritoneal dialysis, and six healthy persons. The study was performed in two phases (1 week apart). In phase A, we used unfractionated heparin (5000 IU, intravenous), whereas in phase B, low-molecular-weight heparin (3500 anti-FXa, intravenous) was used. Total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and Lp(a) were estimated before and 1, 2, 3, and 4 hours after heparin administration. We observed a reduction only in triglycerides (at the first, second, and third hour) in both phases in all groups. The other lipid parameters were not affected. In conclusion, acute administration of both types of heparin seems to affect only triglyceride levels in patients on renal replacement therapy.

Effects of statin therapy on the progression of chronic kidney disease

Statins are lipid-lowering agents that specifically, competitively, and reversibly inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the enzyme that catalyzes the conversion of HMG-CoA to mevalonic acid, the rate-limiting step in the formation of cholesterol. A large body of evidence from numerous, well-controlled, randomized trials demonstrates that statins significantly reduce fatal and nonfatal cardiovascular events in the general population. Cardiovascular benefits of statins have been conventionally attributed to reduction in levels of low-density lipoprotein cholesterol. More recently, subanalyses of large clinical trials suggest that statins may also prove beneficial in ameliorating the progression of kidney disease through their cholesterol-dependent and/or cholesterol-independent (pleiotropic) effects. This review focuses on the role of statin therapy in the progression of chronic kidney disease, the published trials that study the effect of antilipidemic agents on nephropathy, and the emerging pleiotropic effects of statins on the kidneys.

Lipoprotein(a)- and low-density lipoprotein-derived cholesterol in nephrotic syndrome: Impact on lipid-lowering therapy?

BACKGROUND

Patients with nephrotic syndrome have the highest lipoprotein(a) [Lp(a)] concentrations known. Lp(a) is an low-density lipoprotein (LDL)-like particle consisting of 45% cholesterol. The usual methods to determine LDL cholesterol do not distinguish between cholesterol derived from LDL and Lp(a) and are thus the net result of cholesterol levels from both lipoproteins. High Lp(a) concentrations therefore significantly contribute to the measured or calculated LDL cholesterol levels. Since statins have no influence on Lp(a) levels, it can be expected that the LDL cholesterol-lowering effect of statins may be diminished in patients who have a pronounced elevation of Lp(a) levels accompanied by only moderate elevations of LDL cholesterol.

METHODS

We investigated 207 patients with nondiabetic nephrotic syndrome in whom Lp(a) concentrations were strikingly elevated when compared to 274 controls (60.4 +/- 85.4 mg/dL vs. 20.0 +/- 32.8 mg/dL, P < 0.0001).

RESULTS

According to National Kidney Foundation Dialysis Outcomes Quality Initiative (K/DOQI) Clinical Practice Guidelines for Managing Dyslipidemias, almost 95% of these patients are candidates for a therapeutic intervention to lower LDL cholesterol. LDL cholesterol levels corrected for Lp(a)-derived cholesterol, however, were 27 mg/dL lower than uncorrected concentrations (compared to only 9 mg/dL in controls). If Lp(a)-corrected levels instead of total LDL cholesterol levels were used, 25.7% of patients with low-molecular-weight (LMW) apolipoprotein(a) [apo(a)] isoforms were classified no longer to be in need of LDL cholesterol-lowering therapeutic intervention compared to only 2.3% of patients with high-molecular-weight (HMW) apo(a) phenotypes (P < 0.00001). This ("pseudo") pharmacogenetic effect results in incorrect determination of LDL cholesterol.

CONCLUSION

Our observation has an impact on the indication for, and assessment of efficacy of intervention. This potential artifact should be investigated in ongoing large trials in renal patients as well as in nonrenal African American subjects who have on average markedly higher Lp(a) levels. In nonrenal Caucasian subjects with much lower Lp(a) concentrations, this issue will be less relevant.

Are HMG-CoA reductase inhibitors underutilized in dialysis patients?

Patients with end-stage renal disease (ESRD) treated with dialysis have a dramatically elevated rate of cardiovascular disease (CVD) compared to the general population. Lipid-lowering therapy with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors ("statins") has been shown to markedly reduce cardiovascular risk in patients without renal failure, but their effect has not been fully studied in the dialysis population. In this article we will first discuss the known benefits of statin therapy in the general population and summarize the current guidelines for such therapy. We will then examine the evidence linking dyslipidemia and cardiac disease in the dialysis population and discuss possible pathophysiologic mechanisms by which statins could prevent cardiac disease in these patients. We will also review prior clinical studies of the effects of statins in patients on dialysis, with particular attention to the safety and efficacy of these drugs in this population. Finally, we will review how statins are currently being used in the care of dialysis patients and suggest whether an expanded utilization of these drugs could help reduce the enormously high rates of cardiac disease in this patient population.

Meta-analysis of the effect of sevelamer on phosphorus, calcium, PTH, and serum lipids in dialysis patients

Hyperphosphatemia and dyslipidemia are common clinically significant conditions in end-stage renal disease (ESRD). Hyperphosphatemia management is essential; however, use of calcium-based phosphate binder has been associated with elevated risk of cardiac calcification in ESRD, increasing risks for cardiovascular disease and death. An alternative to calcium-based phosphate binders is sevelamer hydrochloride, a calcium-free, metal-free, nonabsorbed polymer that binds phosphate effectively. We conducted a meta-analysis on the effects of sevelamer hydrochloride on parameters of mineral metabolism (serum phosphorous, calcium, Ca x P, and iPTH) and the lipid profile (total, LDL, HDL, and non-HDL cholesterol, and triglycerides) in dialysis patients. After application of inclusion/exclusion criteria, 17 core studies were statistically analyzed to determine the sevelamer treatment effect on the study parameters as demonstrated by simple, n-weighted, and inverse variance-weighted mean changes. Analysis of inverse variance-weighted mean changes indicated that sevelamer treatment was associated with a 2.14 mg/dL drop in serum phosphorus (P <.001), no significant overall effect on calcium (0.09 mg/dL, P =.364), significant decline in Ca x P product (15.91 mg(2)/dL(2), P <.001), 35.99 pg/mL reduction in iPTH (P =.026), significant reduction in total cholesterol (30.58 mg/dL, P <.001), 31.38 mg/dL drop in LDL cholesterol (P <.001), significant increase in HDL cholesterol (4.09 mg/dL, P =.008), and a significant reduction in triglycerides (22.04 mg/dL, P x.001). This meta-analysis suggests that sevelamer offers a dual therapeutic benefit in dialysis patients-a population at high risk for cardiovascular disease-by improving phosphorus control and the lipid profile, without altering serum calcium.

Drug-induced renal function impairment: a population-based survey

PURPOSE

The knowledge that drugs can affect renal function is mainly based on experimental studies or case reports. Thus, it has only been investigated in selected populations. Here we describe drug groups associated with altered renal function in the general population.

METHODS

To study this, we used baseline data of 8592 subjects of a population-based cohort. Hyper- and hypofiltration were defined as a filtration above or below the 90% confidence interval of age-and-sex-corrected creatinine clearance. Drug use was measured in the year preceding the kidney function measurement.

RESULTS

The prevalence of hyperfiltration (4.6% in the general population) was higher among subjects using anti-diabetics (11.7%), dermatological corticosteroids (5.9%) and sex hormones (5.8%), but lower in subjects using anti-thrombotics (2.4%) and diuretics (2.1%). Hypofiltration (4.3% in the general population) was seen more often in users of beta blockers (6.2%), ACE inhibitors (7.1%), statins (7.2%), anti-thrombitics (6.8%), trimethoprim (7.9%), vaccines (9.4%), NSAIDs (5.2%), anti-ulcer agents (6.3%), laxatives (7.7%) and eyedrops (6.7%).

CONCLUSIONS

Several drug groups found in this overview were to be expected, since patients with kidney disease often use them (e.g. cardiovascular drugs). Several other drug groups were somewhat unexpected and deserve further attention.

A multidisciplinary program for achieving lipid goals in chronic hemodialysis patients

BACKGROUND

There is little information on how target lipid levels can be achieved in end stage renal disease (ESRD) patients in a systematic, multidisciplinary fashion.

METHODS

We retrospectively reviewed a pharmacist-directed hyperlipidemia management program for chronic hemodialysis (HD) patients. All 26 adult patients on chronic HD at a tertiary care medical facility were entered into the program. A clinical pharmacist was responsible for laboratory monitoring, patient counseling, and the initiation and dosage adjustment of an appropriate 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor (statin) using a dosing algorithm and monitoring guidelines. The low-density lipoprotein (LDL) cholesterol goal was leq; 100 mg/dl. A renal dietitian provided nutrition counseling and the nephrologist was notified of potential or existing drug interactions or adverse drug reactions (ADRs). Patients received a flyer containing lipid panel results to encourage compliance. Data was collected at program initiation and for 6 months thereafter.

RESULTS

At the start of the program, 58% of patients were at target LDL cholesterol. At 6 months, 88% had achieved target LDL (p = 0.015). Mean LDL cholesterol decreased from 96 +/- 5 to 80 +/- 3 mg/dl (p < 0.01), and mean total cholesterol decreased from 170 +/- 7 to 151 +/- 4 mg/dl (p < 0.01). Fifteen adjustments in drug therapy were made. Eight adverse drug reactions were identified; 2 required drug discontinuation or an alternative agent. Physicians were alerted to 8 potential drug-drug interactions, and appropriate monitoring was performed.

CONCLUSIONS

Our findings demonstrate both feasibility and efficacy of a multidisciplinary approach in management of hyperlipidemia in HD patients.

Evaluation of five methods for determining low-density lipoprotein cholesterol (LDL-C) in hemodialysis patients(1)

OBJECTIVES

Current recommendations for the management of dyslipidemia are largely based on the concentration of LDL-C. Most clinical laboratories estimate the concentration of LDL-C by the recommended routine method, the equation of Friedewald, in specimens from fasting subjects and with TG concentrations < 4.52 mmol/L. Because of the limitations of the Friedewald calculation, direct methods for an accurate quantification of LDL-C are needed.

DESIGN AND METHODS

In the present study we evaluated the accuracy of the following 5 different procedures for LDL-C in 98 patients on hemodialysis: the Friedewald equation, where LDL-C is calculated from HDL-C, measured either by the precipitation procedure with dextran sulfate-Mg(2+) (Method 1), or by a direct HDL-C assay (Method 2), the Direct LDL assay (Method 3), the homogeneous N-geneous LDL assay (Method 4) and the calculated LDL-C values deriving from the ApoB based equation: 0.41TC - 0.32TG + 1.70ApoB - 0.27, (Clin Chem 1997;43:808-815) (Method 5).

RESULTS

All five LDL-C methods were found to be in good agreement with ultracentrifugation/dextran sulfate-Mg(2+) precipitation with the coefficients of correlation of the assays to ranging between 0.93-0.95. However, significant differences in the mean values and biases vs. the reference method were observed. The Friedewald equation and the Direct assay were less affected by high LDL-C levels, and they presented higher sensitivity and higher negative predictive value. The N-geneous assay and the ApoB derived calculation were less affected by high triglyceride levels, and they presented higher specificity and higher positive predictive value. At the diagnostic LDL-C level of 3.37 mmol/L, both Friedewald calculations correctly classified 82/92 patients; Direct assay 86/98; N-geneous assay 88/98; and ApoB derived calculation 88/98. At the diagnostic LDL-C level of 2.98 mmol/L, Friedewald calculations (Method 1 and Method 2) correctly classified 82/92 and 81/92 patients, respectively; Direct assay (LDL-3) 87/98; N-geneous assay (LDL-4) 91/98; and ApoB derived calculation (LDL-5) 91/98.

CONCLUSIONS

Among hemodialysis patients, who commonly present "average" LDL-C concentrations and high TG levels, the N-geneous assay and the apoB derived calculation seem to yield more acceptable results for the estimation of LDL-C.

Dyslipidemia and renal disease: pathogenesis and clinical consequences

Patients with chronic renal disease suffer from a secondary form of complex dyslipidemia. The most important abnormalities are an increase in serum triglyceride levels (elevated VLDL-remnants/IDL), small LDL particles and a low HDL cholesterol level. The highly atherogenic LDL subclass, namely LDL-6 or small dense LDL, accumulates preferentially in hypertriglyceridemic diabetic patients with nephropathy or on hemodialysis treatment. All these lipoprotein particles contain apolipoprotein B, thus the complex disorder can be summarized as an elevation of triglyceride-rich apolipoprotein B-containing complex lipoprotein particles. Growing evidence suggests that all of the components of this type of dyslipidemia are independently atherogenic. These particles, specifically the apolipoprotein B moiety, are predominantly prone to modification such as oxidation and glycosilation, which contributes to impaired clearance by the LDL receptor. These complex alterations in lipoprotein composition not only passively accompany chronic renal disease but on the contrary also promote its progression and the development of atherosclerosis. Therefore, renal patients with dyslipidemia should be subjected to lipid-lowering therapy. The effectiveness of lipid lowering on the reduction of cardiovascular endpoints or the progression of renal disease is under investigation or remains to be studied.

Premature cardiovascular disease in chronic renal failure

There is a remarkable lack of reliable information about the determinants of risk of cardiovascular disease (CVD) among patients with chronic renal failure. Indeed, such patients have often been deliberately excluded from randomised trials of treatments of CVD, perhaps because of concerns about drug safety. But the absolute risk of CVD among them may be large, so the potential absolute benefits of treatments may also be large, and may well exceed any increased hazards. Hence, as well as further investigation of the underlying mechanisms of cardiac disease, it would be helpful to have some large-scale randomised trials in a wide range of renal patients of interventions (such as cholesterol-lowering drugs, antihypertensives, aspirin, B-vitamins, and antioxidant vitamins) that are of proven or suspected benefit in other settings. If safe and effective treatments can be identified, and started early in the natural history of renal failure, the exceptionally high risk of CVD experienced by these patients could be decreased before and after end-stage renal failure has occurred.