Prevention of Venous Thromboembolism in Medical Patients with Thrombocytopenia or with Platelet Dysfunction: A Review of the Literature

Abstract

Current guidelines for venous thromboembolism (VTE) primary prophylaxis are based on randomized clinical trials that exclude subjects at a potentially high bleeding risk. Thus no specific recommendation/algorithm for pharmacological prophylaxis in patients with thrombocytopenia and/or platelet dysfunction is available. Because at least 25% of subjects admitted to medical departments exhibit these conditions, information on this subject is provided here to optimize their VTE prophylaxis. Low platelet number/function and clotting abnormalities are common in patients with liver cirrhosis. However, these patients have a high incidence of portal and idiopathic venous thromboses, implying that cirrhotic coagulopathy does not protect against thrombosis. At variance with severe thrombocytopenia (< 50,000/mL), mild/moderate thrombocytopenia (> 50,000/mL) should not interfere with VTE prevention decisions. In severe thrombocytopenia, prophylaxis should be considered on an individual basis, however. In patients with antiphospholipid antibodies and thrombocytopenia, a thrombotic tendency is usually associated rather than a bleeding risk. VTE prophylaxis in high-risk conditions is thus suggested in these patients. Except in cases with contraindications to anticoagulation, antithrombotic prophylaxis should be always considered in hospitalized cancer patients with thrombocytopenia, especially in those with hematologic malignancies and multiple VTE risk factors. Aspirin treatment is not as effective as heparins in lowering the risk of VTE. Studies in stroke suggest that thromboprophylaxis with heparins is safe in patients with ischemic stroke undergoing aspirin treatment. The need for VTE prophylaxis in patients on chronic treatment with aspirin and/or clopidogrel should be evaluated after assessing the individual risk-benefit ratio.

Management and outcomes of cancer-associated venous thromboembolism in patients with concomitant thrombocytopenia: a retrospective cohort study

“…In our cohort, anticoagulant prophylaxis was not being administered in 91.9 % of patients who developed VTE during their hospitalization, likely due to a concern for bleeding. While there is no evidence available from randomized control trials to establish the safety and efficacy of anticoagulant prophylaxis in thrombocytopenic cancer patients, data do exist to show that patients with moderate or even severe thrombocytopenia can tolerate low doses of heparin or LMWH [22,24]. Since prophylactic doses of anticoagulation introduce considerably lower hemorrhagic risks than do therapeutic doses, it would seem that VTE prevention in thrombocytopenic patients is important in order to reduce VTE and the need for therapeutic anticoagulation.…”

Impact of dengue-induced thrombocytopenia on mandatory anticoagulation for patients with prosthetic heart valves on warfarin

“…We did not use low-molecular-weight heparin as a bridging therapy, as there is a paucity of evidence to support this. (5) In conclusion, our patients had favourable outcomes with careful adjustment of warfarin dosing for their prosthetic valves in the setting of acute dengue fever with thrombocytopenia. Future studies should be undertaken to develop clinical guidelines for patients on mandatory anticoagulation who have dengue with warning signs or are at risk of bleeding, especially for those residing in endemic countries.…”

How I evaluate and treat thrombocytopenia in the intensive care unit patient

“…48 In the absence of prospective randomized trials, a widely used protocol in patients with malignancyassociated thrombocytopenia who have comorbidities, but who typically require therapeutic-dose anticoagulation (eg, for the treatment of symptomatic venous thromboembolism), is to reduce therapeutic-dose anticoagulation by half if the platelet count falls below 50 3 10 9 /L, to use prophylactic dose anticoagulation if the platelet count falls below 30 3 10 9 /L, and to stop all anticoagulants if the platelet count falls below 20 3 10 9 /L. 49,50 Patients with ITP have an increased risk of thrombosis, 51 as do patients with intracranial hemorrhage undergoing neurosurgery.…”