Research

Correlation between rivaroxaban (Xarelto) plasma activity, patient clinical variables and outcomes in a South African centre

S Louw, N P Saragas, P N Ferrao, T F Chirwa, B F Jacobson

Abstract


Background. Low-molecular-weight heparin and vitamin K antagonists such as warfarin are the gold standard for prohylaxis and treatment of venous thromboembolic disease (VTED). Direct oral anticoagulants (DOACs) result in predictable anticoagulation with significantly reduced inter- and intra-patient variability. DOAC absorption is rapid, with a short half-life and relatively few drug interactions. DOACs are effective and safe at fixed doses without activity monitoring. However, specific situations may require assessment of accurate drug activity. Rivaroxaban, a DOAC targeting activated coagulation factor X (FXa), is registered for the prevention and treatment of VTED in South Africa.

Objectives. To establish a prophylactic rivaroxaban activity level range and determine any associations with clinical complications, viz. haemorrhage and/or thrombosis.

Methods. Samples from 115 orthopaedic patients were tested 3 hours after a prophylactic oral dose of 10 mg rivaroxaban with STAGO rivaroxaban anti-FXa reagent on an automated coagulation analyser. Patient demographics and clinical outcomes were documented.

Results. The mean rivaroxaban anti-FXa level was 105.7 ng/mL. Two patients developed adverse events on therapy. One patient had minor bleeding (menorrhagia) (drug activity level 288.7 ng/mL) and another a deep-vein thrombosis (drug activity level 34.7 ng/mL). Statistical analysis demonstrated an association between drug activity and advancing age (p=0.008), most apparent among those aged ≥65 years.

Conclusions. Measuring rivaroxaban activity levels reduces uncertainty if treatment failure and complications occur. Patients aged ≥65 years should be closely monitored. A local rivaroxaban activity level for patients on rivaroxaban prophylaxis has been established.


Authors' affiliations

S Louw, Department of Molecular Medicine and Haematology, University of the Witwatersrand, Johannesburg; National Health Laboratory Service, Johannesburg, South Africa

N P Saragas, Netcare Linksfield Orthopaedic Sports and Rehabilitation Centre (Clinic), Department of Orthopaedics, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

P N Ferrao, Netcare Linksfield Orthopaedic Sports and Rehabilitation Centre (Clinic), Department of Orthopaedics, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

T F Chirwa, Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

B F Jacobson, Department of Molecular Medicine and Haematology, University of the Witwatersrand, Johannesburg; and National Health Laboratory Service, Johannesburg, South Africa

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Keywords

Anticoagulation; Elderly; Monitoring

Cite this article

South African Medical Journal 2016;106(10):1017-1020. DOI:10.7196/SAMJ.2016.v106i10.10584

Article History

Date submitted: 2016-01-26
Date published: 2016-09-08

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