Hamostaseologie 2019; 39(S 01): S1-S92
DOI: 10.1055/s-0039-1680149
SY18 Oral Anticoagulants
Georg Thieme Verlag KG Stuttgart · New York

Determinants of the Quality of Warfarin Control and Validation of the SAMe-TT2-R2 Score for Acute Venous Thromboembolism. An Analysis of the Hokusai-VTE Trial

S. Barco
1   Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
,
S. Granziera
2   Department of Physical and Rehabilitation Medicine, Villa Salus Hospital, Mestre, Italy
,
M. Coppens
3   Department of Vascular Medicine, Amsterdam Cardiovascular Sciences, Amsterdam UMC, Location AMC, Amsterdam, The Netherlands
,
J. Douxfils
4   Department of Pharmacy, Thrombosis and Hemostasis Center, Research Institute for Life Sciences, University of Namur, Namur, Belgium
,
M. Nijkeuter
5   Department of Internal Medicine, University Medical Centre Utrecht, Utrecht, The Netherlands
,
N. Riva
6   Department of Pathology, Faculty of Medicine and Surgery, University of Malta, Msida, Malta
,
T. Vanassche
7   Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
,
G. Zhang
8   Daiichi Sankyo Inc., Basking Ridge, New Jersey, United States
,
M. Lin
8   Daiichi Sankyo Inc., Basking Ridge, New Jersey, United States
,
P. Kamphuisen
9   Department of Internal Medicine, University Medical Center, Groningen, The Netherlands
,
A. Cohen
10   King's College London, Guy's and St Thomas' NHS Foundation Trust Hospital, London, United Kingdom
,
J. Beyer-Westendorf
11   Division Hematology, Department of Medicine I, Thrombosis Research Unit, University Hospital Carl Gustav Carus, Dresden, Germany
12   Department of Hematology, Kings College London, Kings Thrombosis Service, London, United Kingdom
› Author Affiliations
Further Information

Publication History

Publication Date:
13 February 2019 (online)

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Background: Time in therapeutic range (TTR) measures the quality of vitamin K antagonist (VKA) anticoagulation. The dichotomized SAMe-TT2-R2 score can predict, among patients with atrial fibrillation, if adequate TTR is likely to be achieved.

Methods: We validated the score in patients with acute venous thromboembolism (VTE) randomized to the warfarin arm of the Hokusai-VTE trial: a total of 3,874 patients were included in the analysis. The primary efficacy and safety outcomes were symptomatic recurrent VTE and the composite of major or clinically-relevant-non-major bleeding, respectively.

Results: The rates of recurrent VTE and bleeding events were higher in patients with a TTR below the median (TTR< 66% versus ≥66%) resulting in an absolute risk difference [ARD] of +0.5% (95%CI 0%; +1.1%) and +2.2% (0.9%; +3.5%), respectively. Patients with a high SAMe-TT2-R2 score (76% of total) had lower median TTR than patients with a low SAMe-TT2-R2 score (64.7% versus 70.7%, respectively). The SAMe-TT2-R2 score had poor negative (0.59) and positive (0.52) predictive values (TTR cut-off 66%), and exhibited poor discrimination (c-statistic 0.58). Patients with a high (versus low) SAMe-TT2-R2 score had similar rates of recurrent VTE (ARD 0% [-0.6%; +0.7%]) and bleeding (ARD +1.3% [-0.1%; +2.7%]).

Conclusions: In the setting of acute VTE, the SAMe-TT2-R2 score showed unsatisfactory discrimination and predictive value for individual TTR: therefore, the choice of starting a patient on VKA cannot be based on this parameter. Since the SAMe-TT2-R2 score did not correlate well with clinical outcomes, its routine use in acute VTE may not translate into clinical usefulness.