Prevention of venous thromboembolism in hospitalized patients with chronic kidney disease

Despite the high morbidity and mortality associated with venous thromboembolism in hospitalized medical patients with a number of risk factors, and large evidence that prophylaxis is effective, prophylaxis rates remain elusive in medically ill patients. Furthermore, in patients with renal failure, prophylaxis often is omitted or sub-optimal, due to fear of provoking hemorrhage. Patients with end-stage renal disease often have platelet deficits. Low molecular weight heparin (LMWH) therapy may also be difficult to manage in these cases because LMWH clearance is largely dependent on the kidneys. Administration of LMWH to patients with some degree of renal failure may lead to bioaccumulation of anti-Xa activity with an increased risk of bleeding. In recent years, LMWH has largely replaced unfractionated heparin (UFH) for the treatment and prophylaxis of thromboembolic disease. LMWHs have been shown to be superior to UFH in the prevention of venous thromboembolism. They are also easier to administer and do not require laboratory monitoring. However, several case reports and a metaanalysis indicate that the use of LMWHs at therapeutic doses in patients with advanced renal failure can be associated with major bleeding with serious adverse effects. In this paper, we review recent evidence supporting the safety of LMWHs at prophylactic doses in patients with mild or moderate renal disease. Current evidence suggests that bioaccumulation of enoxaparin (the most widely used LMWH) can occur when the drug is used at standard therapeutic doses in patients with severely impaired renal function. This risk can be reduced by empiric dose reduction or monitoring of anti-Xa heparin levels.