"These results indicate a high benefit/risk ratio of aspirin in a polycythemic population, suggesting that aspirin should be used in all patients with polycythemia vera having no contraindication to this treatment," said Raffaele Landolfi, M.D., of the Istituto di Medicina Interna e Geriatria, Università Cattolica, Rome, Italy, lead author of the study.
Aspirin treatment (100 mg per day) significantly reduced the risk of thrombosis in polycythemic patients who were undergoing standard cytoreductive treatments (therapies aimed at reducing the number of blood cells). Treatment with aspirin lowered the risk of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, pulmonary embolism, and venous thrombosis. The risk of minor thrombotic events was also significantly decreased.
Researchers reported no excess of major bleeding in patients on aspirin treatment. Major, total, and gastrointestinal bleedings were not significantly increased. Only the risk of nosebleeds, or epistaxix, was significantly increased.
Polycythemia vera is an acquired disorder of the bone marrow that causes the overproduction of all three blood cell lines – white and red blood cells and platelets. It is a relatively rare disease that occurs more frequently in men than women, usually within the age range of 40 to 80, although it may occur in younger subjects. Polycythemia vera develops slowly, and most patients do not experience any problems related to the disease after being diagnosed. However, the abnormal bone marrow cells may begin to grow uncontrollably in some patients leading to blood hyperviscosity.
Patients with polycythemia vera have an increased tendency to form blood clots that can result in strokes or heart attacks. Some patients may experience abnormal bleeding because their platelets are abnormal, but the major cause of death is thrombosis. The objective of treatment is to reduce high viscosity, or blood thickness, and to prevent uncontrollable bleeding and thrombosis. Removing some of the patient's blood periodically, called cytoreduction, is a common treatment.
The ECLAP Study (Efficacy and Safety of Low Dose Aspirin in Polycythemia Vera) was a multi-center, parallel, double-blind clinical trial that randomized 512 patients from 12 different countries to receive either 100 mg of aspirin daily or a placebo. By comparison, many over-the-counter aspirin tablets are often 325 mg. Sixty percent of the study population were males, with a mean age of 61 years, who had had the disease for an average of seven years. Patients were excluded from the trial if they needed antithrombotic therapy, had a contraindication to aspirin, or were unwilling to properly participate.
"This comprehensive study, showing mostly safe patient responses to aspirin, is an important therapeutic step for polycythemia vera patients who are predisposed to serious complications from clotting," said Ronald Hoffman, M.D., President of the American Society of Hematology. "Patients with abnormal levels of blood cells are at increased risk of developing life-threatening blood clots and bleeding, and, in some cases, may develop leukemia."
The American Society of Hematology is the world's largest professional society concerned with the causes and treatment of blood disorders. Its mission is to further the understanding, diagnosis, treatment, and prevention of disorders affecting blood, bone marrow, and the immunologic, hemostatic, and vascular systems, by promoting research, clinical care, education, training, and advocacy in hematology.