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Correspondence |

The SAMe-TT2R2 ScoreNew Score Far From Clinical Application: Far From Clinical Application FREE TO VIEW

Han Zhang, PhD; Yanmin Yang, PhD; Jun Zhu, MD
Author and Funding Information

From the Emergency and Intensive Care Center, Fuwai Hospital; and Chinese Academy of Medical Sciences and Peking Union Medical College.

Correspondence to: Yanmin Yang, PhD, Emergency and Intensive Care Center, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishilu Road, Xicheng District, Beijing, 100037, China; e-mail: yymwin@gmail.com


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(2):418-419. doi:10.1378/chest.13-2109
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Published online
To the Editor:

In a recent article in CHEST (November 2013), Apostolakis et al1 presented a new score to predict poor anticoagulation control and aid decision-making among patients with atrial fibrillation (AF) who are receiving vitamin K antagonists (VKAs). However, we are concerned about the following issues.

First, data of 2,080 patients in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial were used to develop and validate the SAMe-TT2R2 (sex female, age < 60 years, medical history [more than two comorbidities], treatment [interacting drugs, eg, amiodarone for rhythm control], tobacco use [doubled], race [doubled]) score. However, some noteworthy parameters, such as VKA inception status, alcohol abuse, and genotype, that have been identified as important predictors of quality of anticoagulation control were not included in the current analysis. Furthermore, the AFFIRM cohort included patients with valvular AF or patients with nonvalvular AF. However, it is important to predict the anticoagulation control in these respective groups because anticoagulation intensity and quality of anticoagulation control in patients with valvular AF might be quite different from those with nonvalvular VAF.

Second, time in therapeutic range (TTR) is the most common index of anticoagulation quality and could be determined by various methods. In the Apostolakis et al1 article, TTR was measured using the fraction of international normalized ratios (INRs) within the therapeutic range in the AFFIRM population and by the Rosendaal linear interpolation method in the external validation cohort, which would bias the SAMe-TT2R2 score. Some other variables not mentioned in the article, including whether INRs were obtained in the first month after VKA treatment2 and whether there were gaps of > 56 days between INR tests,3 may also influence the results and bias the model.

Third, anticoagulation control varied extensively among different study settings and may be affected by different factors.4 In the Apostolakis et al1 article, although the scheme was externally validated in a “real world” registry, the number of patients seems to be not large enough (n = 286) to test performance of the score effectively. Therefore, we fully support a validation of the SAMe-TT2R2 score in a larger cohort in clinical practice and in different populations.

Finally, the score demonstrated good discrimination performance for patients in the external validation cohort in the fifth (0.36) TTR percentile (c-index = 0.7), but poor performance for the 10th (0.45) and 25th (0.55) percentiles (c-index = 0.62 and 0.58, respectively). It is, therefore, definitely not acceptable in daily practice when using a TTR of 58% to 65% as a cutoff.5 We would greatly appreciate the authors’ consideration of our concerns about clinical application of the SAMe-TT2R2 score.

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.
 
Erkens PM, ten Cate H, Büller HR, Prins MH. Benchmark for time in therapeutic range in venous thromboembolism: a systematic review and meta-analysis. PLoS ONE. 2012;7(9):e42269. [CrossRef] [PubMed]
 
Rose AJ, Miller DR, Ozonoff A, et al. Gaps in monitoring during oral anticoagulation: insights into care transitions, monitoring barriers, and medication nonadherence. Chest. 2013;143(3):751-757. [PubMed]
 
Arbring K, Uppugunduri S, Lindahl TL. Comparison of prothrombin time (INR) results and main characteristics of patients on warfarin treatment in primary health care centers and anticoagulation clinics. BMC Health Serv Res. 2013;13:85. [CrossRef] [PubMed]
 
Connolly SJ, Pogue J, Eikelboom J, et al; ACTIVE W Investigators. Benefit of oral anticoagulant over antiplatelet therapy in atrial fibrillation depends on the quality of international normalized ratio control achieved by centers and countries as measured by time in therapeutic range. Circulation. 2008;118(20):2029-2037. [CrossRef] [PubMed]
 

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Tables

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.
 
Erkens PM, ten Cate H, Büller HR, Prins MH. Benchmark for time in therapeutic range in venous thromboembolism: a systematic review and meta-analysis. PLoS ONE. 2012;7(9):e42269. [CrossRef] [PubMed]
 
Rose AJ, Miller DR, Ozonoff A, et al. Gaps in monitoring during oral anticoagulation: insights into care transitions, monitoring barriers, and medication nonadherence. Chest. 2013;143(3):751-757. [PubMed]
 
Arbring K, Uppugunduri S, Lindahl TL. Comparison of prothrombin time (INR) results and main characteristics of patients on warfarin treatment in primary health care centers and anticoagulation clinics. BMC Health Serv Res. 2013;13:85. [CrossRef] [PubMed]
 
Connolly SJ, Pogue J, Eikelboom J, et al; ACTIVE W Investigators. Benefit of oral anticoagulant over antiplatelet therapy in atrial fibrillation depends on the quality of international normalized ratio control achieved by centers and countries as measured by time in therapeutic range. Circulation. 2008;118(20):2029-2037. [CrossRef] [PubMed]
 
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