SAMe-TT₂R₂ score for poor INR control

SAMe-TT₂R₂ score for poor INR control

SAMe-TT₂R₂ score aims at predicting those likely to have poor INR (International Normalized Ratio of Prothrombin Time) control while on vitamin K antagonists [1]. The investigators divided the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial cohort randomly into a derivation cohort and an internal validation cohort.

They used linear regression analysis to find out the clinical parameters associated with time in therapeutic window (TTR) while on warfarin. Binary logistic regression analysis was used to evaluate the predictive performance of a model created using these factors. The prediction model was externally validated using a prospectively recruited cohort receiving anticoagulation.

SAMe-TT₂R₂ score derived thus had the following parameters:

Sex female

Age < 60 years

Medical history (more than two comorbidities)

Treatment (interacting drugs, eg, amiodarone for rhythm control)

Tobacco use (doubled)

Race (doubled)

Those with scores of zero or 1 did well on warfarin with good TTR. In those with a score of 2 or more, additional interventions are required to achieve adequate anticoagulation. Direct oral anticoagulants (DOACs) may be considered in patients with a score of two or more.

It is not very sure whether this score will do well in those with valvular heart disease as 95% of patients enrolled in the AFFIRM trial did not have valvular disease.

Lip GYH et al evaluated 4,637 patients who were receiving vitamin K antagonists to see whether SAMe-TT₂R₂ score could discriminate those who were likely to have a labile INR, stroke/thromboembolism, clinically relevant bleeding and death while on treatment [2]. They found a significant increase in risk of severe bleeding in patients with a high SAMe-TT₂R₂ score (> 2). Increasing SAMe-TT₂R₂ score was associated with an increasing risk of labile INR, stroke/thromboembolism, severe bleeding and death on follow-up. Mean follow-up period was 1,016 days in that study.

Another study which retrospectively checked 911 patients with non-valvular atrial fibrillation on vitamin K antagonists also reached similar conclusions [3]. They found that SAMe-TT₂R₂ score is a clinical tool useful to identify patients who have poor quality of anticoagulation control. SAMe-TT₂R₂ score successfully predicted the composite outcome of major bleeding, thromboembolic complications and death.

References

1. Apostolakis S, Sullivan RM, Olshansky B, Lip GYH. Factors affecting quality of anticoagulation control among patients with atrial fibrillation on warfarin: the SAMe-TT₂R₂ score. Chest. 2013 Nov;144(5):1555-1563.
2. Lip GYH, Haguenoer K, Saint-Etienne C, Fauchier L. Relationship of the SAMe-TT₂R₂ score to poor-quality anticoagulation, stroke, clinically relevant bleeding, and mortality in patients with atrial fibrillation. Chest. 2014 Sep;146(3):719-726.
3. Abumuaileq RR, Abu-Assi E, Raposeiras-Roubin S, López-López A, Redondo-Diéguez A, Álvarez-Iglesias D, Rodríguez-Mañero M, Peña-Gil C, González-Juanatey JR. Evaluation of SAMe-TT2R2 risk score for predicting the quality of anticoagulation control in a real-world cohort of patients with non-valvular atrial fibrillation on vitamin-K antagonists. Europace. 2015 May;17(5):711-7.