Prevention of Thrombosis in Patients on Hemodialysis by Low-Dose Aspirin

Abstract

Since platelet cyclo-oxygenase is much more sensitive to inactivation by aspirin than is the enzyme in the arterial wall and low doses of aspirin may prevent thrombosis by blocking thromboxane synthesis, we conducted a randomized, double-blind trial of aspirin (160 mg per day) vs. placebo in 44 patients on chronic hemodialysis. The study was continued until there were 24 patients with thrombi and both groups had been under observation for a mean of nearly five months. Thrombi occurred in 18 of 25 (72 per cent) of patients given placebo and 16 of 19 (32 per cent) of those given aspirin (P less than 0.01). The incidence of thrombosis was reduced from 0.46 thrombi per patient month in the placebo group to 0.16 thrombi per patient month in the aspirin group (p less than 0.005). A dose of 160 mg of aspirin per day is an effective, nontoxic antithrombotic regimen in patients on hemodialysis.

Major Bleeding in Hemodialysis Patients

“…Whereas aspirin prolongs the bleeding time in normal volunteers, the effect is exaggerated in CKD (9); however, few studies have evaluated aspirin-associated bleeding risk in HD patients (9,20,21). In addition to the effect on bleeding time, two distinct cyclooxygenase-1 mechanisms contribute to the increased risk for upper GI bleeding: The dosage-independent inhibition of thromboxane A 2 -mediated platelet aggregation and the dosage-dependent inhibition of the prostaglandin H synthase-mediated cytoprotection in the gastric mucosa (6).…”

Arachidonate metabolism in vascular disorders.

“…It is clear that much lower doses of aspirin will effectively block platelet thromboxane production. In a study of prevention of shunt thrombosis in patients on hemodialysis, 160 mg aspirin per day was shown to be effective (30). Currently, several trials are underway to evalute low-dose aspirin as an antithrombotic agent.…”

Eighth Gaddum Memorial Lecture University of London Institute of Education December 1980: Biological Importance of Prostacyclin

“…A dose of aspirin of 160 mg/day has been shown to have an anti-thrombotic effect in arteriovenous shunts in uraemic patients (Harter, Burch, Majerus, Stanford, Delmez, Anderson & Weerts, 1979).…”