The Association of Age with Dosage Requirement for Warfarin

Redwood, M.; Taylor, Clare P. F.; Bain, Barbara J.; Matthews, Jennifer H.

doi:10.1093/ageing/20.3.217

Cited by 64 publications

(26 citation statements)

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“…This has been ascribed to factors that are more common in elderly, such as co-morbidities, use of multiple drugs, reduced metabolic clearance of VKA and pathological changes in the blood vessels [34]. However, not all studies are in agreement with patient age as a risk factor [35], [36]. In a recent study with very old patients (≥80 years) on VKA, the frequency of bleeding complications was low with adequate management, indicating that age per se is not the main relevant risk factor for bleeding [37].…”

Section: Discussionmentioning

confidence: 99%

Platelet Dysfunction in Thrombosis Patients Treated with Vitamin K Antagonists and Recurrent Bleeding

et al. 2013

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BackgroundRecurrent bleeding can complicate the treatment of thrombosis patients with vitamin K antagonists (VKA), even at a well-regulated level of anticoagulation. In this proof-of-principle study, we investigated whether alterations in platelet function or von Willebrand factor (vWf) contribute to a bleeding phenotype in these patients.MethodsIn this case-control study 33 well-regulated patients without bleeding events (controls) and 33 patients with recurrent bleeding (cases) were retrospectively included. Thrombin generation and vWf were determined in plasma. Platelet function was assessed by light transmission aggregometry and flow cytometry using a validated panel of agonists.ResultsThrombin generation was similarly reduced in controls and cases, in comparison to normal plasma. Plasma vWf level was above the normal range in 85% of controls and 67% of the cases. vWf activity was similarly increased in all patients in comparison to healthy volunteers. Platelet aggregation was in the normal range for almost all patients irrespective of the type of agonist. However, in response to a low collagen dose, platelets from 21% of controls and 27% of cases showed diminished responses. Agonist-induced secretion of alpha- and dense-granules or integrin αIIbβ3 activation were affected in platelets from neither controls nor cases.ConclusionRecurrent bleeding in well-controlled patients on VKA therapy is not explained by anti-hemostatic changes in platelet or vWf function.

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Section: Discussionmentioning

confidence: 99%

Platelet Dysfunction in Thrombosis Patients Treated with Vitamin K Antagonists and Recurrent Bleeding

et al. 2013

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“…The dose of oral anticoagulants required to maintain a therapeutic range expressed as the international normalized ratio (INR) for patients over 60 years of age decreases with increasing age, possibly because of a reduction in the clearance of warfarin with age (55)(56)(57)(58). Overall, in elderly patients, the initial dose of warfarin should not exceed 5 mg, or even less in patients with a high risk of bleeding, those undernourished, those who have liver disease, and those who have undergone heart valve replacement surgery (59).…”

Section: Oral Anticoagulantsmentioning

confidence: 99%

Antithrombotic Therapy in the Elderly

Capodanno

Angiolillo

2010

Journal of the American College of Cardiology

122

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Antithrombotic therapy represents the mainstay of treatment for prevention of recurrent ischemic events in patients with atherothrombotic disease processes. Although the benefits of antithrombotic pharmacotherapy in the elderly are well established, the elderly are generally more vulnerable to the adverse effects of antithrombotic drugs. Such higher vulnerability may be related to distinct pharmacokinetic and pharmacodynamic responses in the late age of life, during which drug-drug interactions due to polypharmacy further enhance the risk of adverse effects associated with the use of antithrombotic agents. Given that the prevalence of atherothrombotic disease, as well as diseases with thromboembolic potential, increases exponentially with age and that the elderly population is in continuous growth, understanding strategies of antithrombotic management in these patients is of key importance. The present paper provides an overview of the current available evidence on the use of antithrombotic therapy in elderly patients with the primary focus on treatment of coronary artery disease.

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“…An increased sensitivity to oral anticoagulant drugsespecially to warfarin -in the older age has been demonstrated by several investigators [2,18,4,5]. Gurwitz [4], e.g., reported results of 530 patients monitored in the anticoagulant clinic and found a 1.66 fold higher doseadjusted prothrombin time ratio in patients > 70 years when compared with those < 50 years.…”

Section: Discussionmentioning

confidence: 94%