Warfarin-related outcomes in patients with antiphospholipid antibody syndrome managed in an anticoagulation clinic

 

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Summary

Patients with antiphospholipid antibody syndrome (APA) are at elevated risk of venous and arterial thromboembolic complications. Oral anticoagulation with warfarin is recommended for secondary prevention of thromboembolism, but warfarin-related outcomes have not been systematically investigated when warfarin therapy is managed by a dedicated anticoagulation clinic.The objectives of the study were to evaluate warfarin-related monitoring outcomes, clinical endpoints and the use of healthcare resources as a result of warfarin-related complications in patients with APA compared to a group of patients without APA, all of whom were managed in an anticoagulation clinic setting. A retrospective observational cohort design was used to investigate patients with and without APA, all of whom had a history of venous or arterial thromboembolism, and were matched for age, gender and indication for oral anticoagulation. Thirty-six APA patients taking warfarin were compared to a matched cohort of 36 patients without APA. Monitoring outcomes (time in therapeutic range, clinic visits per year, frequency of warfarin dosing adjustments, reasons for out-of-range INRs) were similar between groups, as was the frequency of major bleeding complications (3.2%/pt-yr vs. 3.1%/pt-yr). However, recurrent thromboembolic events (9.6%/pt-yr vs 0) occurred more frequently in APA patients. APA patients required more emergency room visits (6.4%/pt-yr vs. 1.6%/pt-yr) and hospital admissions (14.4%/pt-yr vs.3.0%/pt-yr) to manage complications of warfarin therapy. In conclusion, despite similar monitoring outcomes obtained in a dedicated anticoagulation clinic setting, adverse clinical outcomes are significantly more frequent in patients with APA syndrome than in those without APA, and require more frequent use of healthcare resources.

• References

• 1 Levine JS, Branch R, Rauch J. The antiphospholipid syndrome. New EnglJ Med 2002; 346: 752-63.
  PubMedGoogle Scholar
• 2 Cervera R, Piette JC, Font J. et al. Antiphospholipid syndrome: clinical and immunologic manifestations and patterns of disease expression ina cohort of 1,000 patients. Arthritis Rheum 2002; 46: 1019-27.
  CrossrefPubMedGoogle Scholar
• 3 Albers GW, Amarenco J, Easton JD. et al. Antithrombotic and thrombolytic therapy for ischemic stroke: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004; 126: 483s-512s.
  CrossrefPubMedGoogle Scholar
• 4 Büller HR, Agnelli G, Hull RD. et al. Antithrombotic therapy for venous thromboembolic disease: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004; 126: 401s-428s.
  CrossrefPubMedGoogle Scholar
• 5 Krnic-Barrie S, O’Connor CR, Looney SW. et al. A retrospective review of 61 patients with antiphospholipid syndrome: analysis of factors influencing recurrent thrombosis. Arch Intern Med 1997; 157: 2101-8.
  CrossrefPubMedGoogle Scholar
• 6 Rosove MH, Brewer PM. Antiphospholipid thrombosis: clinical course after the first thromboembolic event in 70 patients. Ann Intern Med 1992; 117: 303-8.
  CrossrefPubMedGoogle Scholar
• 7 Ruiz-Irastorza G, Shamashta MA, Hunt BJ. et al. Bleeding and recurrent thrombosis in definite antiphospholipid syndrome Analysis of a series of 66 patients treated with oral anticoagulation toa target International Normalized Ratio of 3.5. Arch Intern Med 2002; 162: 1164-9.
  CrossrefPubMedGoogle Scholar
• 8 Khamashta MA, Cuadrado MJ, Mujic F. et al. The management of thrombosis in the antiphospholipid antibody syndrome. N Engl J Med 1995; 332: 993-7.
  CrossrefPubMedGoogle Scholar
• 9 Ansell J. Optimizing the efficacy and safety of oral anticoagulant therapy: high-quality dose management, anticoagulation clinics, and patient self-management. Semin Vasc Med 2003; 03: 261-70.
  Article in Thieme ConnectPubMedGoogle Scholar
• 10 Chiquette E, Amato M, Bussey H. Comparison of an anticoagulation clinic with usual medical care: anticoagulation control, patient outcomes, and health care costs. Arch Intern Med 1998; 158: 1641-7.
  CrossrefPubMedGoogle Scholar
• 11 Witt DM, Sadler MA, Shanahan RL. et al. Effect of a centralized clinical pharmacy anticoagulation service on the outcomes of anticoagulation therapy. Chest 2005; 127: 1515-22.
  CrossrefPubMedGoogle Scholar
• 12 Wittkowsky AK, Devine EB. Frequency and causes of overanticoagulation and underanticoagulation in patients treated with warfarin. Pharmacotherapy 2004; 24: 1311-6.
  CrossrefPubMedGoogle Scholar
• 13 Crowther MA, Ginsberg JS, Julian J. et al. A comparison of two intensities of warfarin for the prevention of recurrent thrombosis in patients with the antiphospholipid antibody syndrome. N Engl J Med 2003; 349: 1133-8.
  CrossrefPubMedGoogle Scholar
• 14 Finazzi G, Marchioli R, Brancaccio V. et al. A randomized clinical trial of high-intensity warfarin versus conventional antithrombotic therapy for the prevention of recurrent thrombosis in patients with the antiphospholipid antibody syndrome (WAPS). J Thromb Haemost 2005; 03: 848-53.
  CrossrefPubMedGoogle Scholar
• 15 Moll S, Oertel TL. Monitoring warfarin therapy in patients with lupus anticoagulants. Ann Intern Med 1997; 127: 177-85.
  CrossrefPubMedGoogle Scholar
• 16 Rosborough TK, Shepard MF. Unreliability of international normalized ratio for monitoring warfarin therapy in patients with lupus anticoagulant. Pharmacotherapy 2004; 24: 838-42.
  CrossrefPubMedGoogle Scholar
• 17 Dentali F, Manfredi E, Crowther M. et al. Long-duration therapy with low molecular weight heparin in patients with antiphospholipid antibody syndrome resistant to warfarin therapy. J Thromb Haemost 2005; 03: 2121-3.
  CrossrefPubMedGoogle Scholar
• 18 Rouby RAS. New approaches to prevention of thrombosis in the antiphospholipid syndrome: hopes, trials, and tribulations. Arthritis Rheum 2003; 48: 3004-8.
  CrossrefPubMedGoogle Scholar