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SAMeTT2R2 Does Not Predict Time in Therapeutic Range of the International Normalized Ratio in Patients Attending a High-Quality Anticoagulation ClinicPredictive Value of SAMeTT2R2 Score FREE TO VIEW

Jane Skov, PhD; Else-Marie Bladbjerg, PhD; Mustafa Vakur Bor, MD, PhD; Jørgen Gram, MD, Dr Med Sci
Author and Funding Information

From the Unit for Thrombosis Research, Institute of Public Health, University of Southern Denmark.

Correspondence to: Jane Skov, PhD, Unit for Thrombosis Research, Institute of Public Health, University of Southern Denmark, c/o Department of Clinical Biochemistry, Hospital of South West Denmark, Finsensgade 35, DK-6700 Esbjerg, Denmark; e-mail: jskov@health.sdu.dk


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2014;145(1):187-188. doi:10.1378/chest.13-1897
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To the Editor:

We read with great interest the recent article in CHEST (November 2013) by Apostolakis et al,1 who presented the SAMeTT2R2 (sex female, age < 60 y, medical history [more than 2 comorbidities], treatment [interacting drugs, eg, amiodarone for rhythm control], tobacco use [doubled], race [doubled]) score as a tool to predict poor international normalized ratio (INR) control in patients with atrial fibrillation treated with vitamin K antagonists (VKAs). The study used a large population from another study of rhythm management (AFFIRM [Atrial Fibrillation Follow-up Investigation of Rhythm Management]) and an external validation cohort, and the authors concluded that the easily applicable SAMeTT2R2 score can aid decision-making regarding VKA or alternative anticoagulant treatment. The cohorts they used received mediocre VKA treatment with a mean time in therapeutic range (TTR) of about 65%.

From our recent study, we determined whether the SAMeTT2R2 score can predict INR control in a high-quality setting.2,3 We applied the SAMeTT2R2 score to patients with atrial fibrillation (n = 182) in whom the average TTR was 76% in 1 year of follow-up according to a baseline interview covering behavioral, clinical, and sociodemographic variables. The average age was 70.2 years, and 54 patients were women. The population only included whites, resulting in a maximal SAMeTT2R2 score of 6 points. A total of 77 patients had a SAMeTT2R2 score of ≥ 2. The TTRs of these patients were the same as those with a SAMeTT2R2 score of 0 to 1 (76%) (Fig 1A). A linear regression model of the variables included in the SAMeTT2R2 score had a very low prediction of TTR (Table 1) in our study population, with only young age and amiodarone use reaching statistical significance. By including these and two other variables (alcohol consumption and perceived stress) shown to be related to TTR,2 the adjusted R2 value could be more than doubled. Only amiodarone users had significantly reduced TTR when using dichotomized variables (Fig 1B).

Figure Jump LinkFigure 1. A, Average TTR of international normalized ratio (lines represent 1 SD) as a function of SAMETT2R2 score (solid line, ≥ 2 [n = 77]; dashed line, 0-1 [n = 105]). B, Various patient characteristics. S indicates sex (solid line, female [n = 54], dashed line, male [n = 128]). A indicates age (solid line, < 60 years [n = 23]; dashed line, > 60 years [n = 159]). Me indicates having the following comorbidities: hypertension, diabetes, myocardial infarction, peripheral artery disease, congestive heart failure, previous stroke, pulmonary disease, or hepatic or renal disease (solid line, ≥ 2 [n = 92]; dashed line, ≤ 1 [n = 90]). T indicates amiodarone (solid line, use [n = 27]; dashed line, nonuse [n = 155]). T2 indicates smoking status (solid line, current smoker [n = 41]; dashed line, nonsmoker [n = 141]). Alcohol indicates weekly alcohol consumption (solid line, > 75th percentile [n = 46]; dashed line, < 75th percentile [n = 136]). Stress indicates the perceived stress score (solid line, > 75th percentile [n = 38]; dashed line, < 75th percentile [n = 144]). *Statistically significant difference between groups. The horizontal line represents average TTR in the entire cohort (76%). SAMETT2R2 = sex female, age < 60 y, medical history (more than 2 comorbidities), treatment (interacting drugs, eg, amiodarone for rhythm control), tobacco use (doubled), race (doubled); TTR = time in therapeutic range.Grahic Jump Location
Table Graphic Jump Location
Table 1 —Linear Regression Models With TTR of INR as Dependent Variable

Model 1 is based on the variables identified in Apostolakis et al,1 whereas model 2 is based on the strongest predicting variables from our single-center Danish study.2,3 INR = international normalized ratio; SAMeTT2R21 = sex female, age < 60 y, medical history (more than 2 comorbidities), treatment (interacting drugs, eg, amiodarone for rhythm control), tobacco use (doubled), race (doubled); TTR = time in therapeutic range.

We fully agree with Apostolakis et al1 that the services of the clinic providing anticoagulant treatment are strongly related to TTR.4 The optimal, evidence-based treatment often is provided by specialized anticoagulation clinics.5 Here, we show that in such a high-quality setting, the SAMeTT2R2 score was not predictive of TTR. The results from our work are limited by a small cohort from a single Danish center, and future multicenter studies of high-quality anticoagulation clinics are needed to identify better patient-related predictors of poor INR control. The SAMeTT2R2 can be considered a first step and may be modified or expanded with additional variables, such as alcohol consumption or perceived stress, to become a universal tool for allocating patients to the proper anticoagulation treatment.

References

Apostolakis S, Sullivan RM, Olshansky B, Lip GYH. Factors affecting quality of anticoagulation control among patients with atrial fibrillation on warfarin: the SAMe-TT2R2score. Chest. 2013;144(5):1555-1563. [CrossRef] [PubMed]
 
Skov J, Leppin A, Bladbjerg EM, Sidelmann JJ, Gram J. Perceived stress predicts the stability of vitamin K-antagonist treatment of anticoagulant clinic patients. Thromb Haemost. 2012;108(3):581-582. [CrossRef] [PubMed]
 
Skov J, Bladbjerg EM, Leppin A, Jespersen J. The influence of VKORC1 and CYP2C9 gene sequence variants on the stability of maintenance phase warfarin treatment. Thromb Res. 2013;131(2):125-129. [CrossRef] [PubMed]
 
Wallentin L, Lopes RD, Hanna M, et al; Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) Investigators. Efficacy and safety of apixaban compared with warfarin at different levels of predicted international normalized ratio control for stroke prevention in atrial fibrillation. Circulation. 2013;127(22):2166-2176. [CrossRef] [PubMed]
 
Kirchhof P, Nabauer M, Gerth A, et al; AFNET registry investigators. Impact of the type of centre on management of AF patients: surprising evidence for differences in antithrombotic therapy decisions. Thromb Haemost. 2011;105(6):1010-1023. [CrossRef] [PubMed]
 

Figures

Figure Jump LinkFigure 1. A, Average TTR of international normalized ratio (lines represent 1 SD) as a function of SAMETT2R2 score (solid line, ≥ 2 [n = 77]; dashed line, 0-1 [n = 105]). B, Various patient characteristics. S indicates sex (solid line, female [n = 54], dashed line, male [n = 128]). A indicates age (solid line, < 60 years [n = 23]; dashed line, > 60 years [n = 159]). Me indicates having the following comorbidities: hypertension, diabetes, myocardial infarction, peripheral artery disease, congestive heart failure, previous stroke, pulmonary disease, or hepatic or renal disease (solid line, ≥ 2 [n = 92]; dashed line, ≤ 1 [n = 90]). T indicates amiodarone (solid line, use [n = 27]; dashed line, nonuse [n = 155]). T2 indicates smoking status (solid line, current smoker [n = 41]; dashed line, nonsmoker [n = 141]). Alcohol indicates weekly alcohol consumption (solid line, > 75th percentile [n = 46]; dashed line, < 75th percentile [n = 136]). Stress indicates the perceived stress score (solid line, > 75th percentile [n = 38]; dashed line, < 75th percentile [n = 144]). *Statistically significant difference between groups. The horizontal line represents average TTR in the entire cohort (76%). SAMETT2R2 = sex female, age < 60 y, medical history (more than 2 comorbidities), treatment (interacting drugs, eg, amiodarone for rhythm control), tobacco use (doubled), race (doubled); TTR = time in therapeutic range.Grahic Jump Location

Tables

Table Graphic Jump Location
Table 1 —Linear Regression Models With TTR of INR as Dependent Variable

Model 1 is based on the variables identified in Apostolakis et al,1 whereas model 2 is based on the strongest predicting variables from our single-center Danish study.2,3 INR = international normalized ratio; SAMeTT2R21 = sex female, age < 60 y, medical history (more than 2 comorbidities), treatment (interacting drugs, eg, amiodarone for rhythm control), tobacco use (doubled), race (doubled); TTR = time in therapeutic range.

References

Apostolakis S, Sullivan RM, Olshansky B, Lip GYH. Factors affecting quality of anticoagulation control among patients with atrial fibrillation on warfarin: the SAMe-TT2R2score. Chest. 2013;144(5):1555-1563. [CrossRef] [PubMed]
 
Skov J, Leppin A, Bladbjerg EM, Sidelmann JJ, Gram J. Perceived stress predicts the stability of vitamin K-antagonist treatment of anticoagulant clinic patients. Thromb Haemost. 2012;108(3):581-582. [CrossRef] [PubMed]
 
Skov J, Bladbjerg EM, Leppin A, Jespersen J. The influence of VKORC1 and CYP2C9 gene sequence variants on the stability of maintenance phase warfarin treatment. Thromb Res. 2013;131(2):125-129. [CrossRef] [PubMed]
 
Wallentin L, Lopes RD, Hanna M, et al; Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) Investigators. Efficacy and safety of apixaban compared with warfarin at different levels of predicted international normalized ratio control for stroke prevention in atrial fibrillation. Circulation. 2013;127(22):2166-2176. [CrossRef] [PubMed]
 
Kirchhof P, Nabauer M, Gerth A, et al; AFNET registry investigators. Impact of the type of centre on management of AF patients: surprising evidence for differences in antithrombotic therapy decisions. Thromb Haemost. 2011;105(6):1010-1023. [CrossRef] [PubMed]
 
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