Ongoing clinical trials of lipid reduction therapy in patients with renal disease

Lipid abnormalities in renal disease are associated with both a progressive decline in renal function and cardiovascular complications. Whether or not lipid anomalies are causal is not yet clear. Experimental studies have demonstrated that potentially atherogenic lipoproteins, such as low density lipoproteins (LDL), are associated with renal pathophysiological changes that result in progressive glomerular and interstitial damage and an ultimate reduction in renal function. These findings indicate that hyperlipidemia accelerates glomerular and interstitial damage in renal disease. Clinical studies also show that renal function declines more rapidly among patients with primary renal disease or diabetic nephropathy who have hyperlipidemia. However, few reports have demonstrated the effect of hypolipidemic agents on the progression of renal function among patients with renal disease, and those renal patients who were treated with lipid-lowering agents have not been clinically studied under large-scale controlled conditions. In addition, although cardiovascular complications are the most important factors associated with mortality in dialysis patients, randomized, large-scale trials studying the relationship between therapeutic intervention by lipid-lowering agents and prevention of cardiovascular complications have not been implemented.

We reviewed controlled and uncontrolled reported studies that examined the effects of lipid-lowering therapy in patients with renal disease.

Most studies showed that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors reduce cholesterol-rich apolipoprotein (apo)B-containing lipoproteins with no effects on renal function or proteinuria among patients with progressive renal disease. Small uncontrolled studies show that simvastatin and probucol moderately reduce proteinuria among patients with membranous nephropathy. One small retrospective study showed that long-term vitamin E therapy reduces aortic calcification in dialysis patients.

Prospective, randomized large-scale trials including ongoing clinical trials of lipid reduction therapy and therapeutic interventions such as the use of the combination therapy with hypolipidemic agents and angiotensin converting enzyme (ACE) inhibitors, vitamins, or LDL apheresis are urgently required. Such trials will clarify the effect of treating dyslipidemia on the progression of renal insufficiency and dialysis-related cardiovascular complications.