Background: Warfarin reduces stroke risk in atrial fibrillation (AF) patients but requires ongoing monitoring. Time in therapeutic range (TTR) is used as a measure of warfarin control, with a TTR less than 60% associated with adverse patient outcomes. The Sex, Age, Medical history, Treatment, Tobacco use, Race (SAMe-TT2R2) score has been identified as a model able to predict warfarin control, but this has been tested in mainly Caucasian populations. Therefore, the aim of this study was to determine the ability of the SAMe-TT2R2 score to predict warfarin control in a Singaporean population consisting of Chinese, Malay, and Indian race.
Methods: Retrospective data were collected from the National Heart Centre Singapore for AF patients receiving warfarin between January and June 2014. The TTR and the SAMe-TT2R2 score were calculated for each patient.
Results: The 1137 non-valvular AF patients had a mean TTR of 58.0 ± 34.3% and a median SAMe-TT2R2 score of 3. The categorized SAMe-TT2R2 scores (2 versus >2) showed a significant reduction in mean TTR for the entire population (63.2% versus 55.8%, P = .0004) and also when categorized according to race for Chinese (62.7% versus 56.9%, P = .0075) and Malay (68.4% versus 50.6%, P = .0131) populations.
Conclusion: The SAMe-TT2R2 tool is effective in predicting warfarin control in a Singaporean population as patients with a score greater than 2 had poor control. The minimum score for non-Caucasian patients is 2; thus, in these patients, the presence of any additional risk factors identified in the SAMe-TT2R2 tool categorizes them as unlikely to achieve adequate warfarin control and possible candidates for alternative anticoagulants.
Keywords: Warfarin; anticoagulant; atrial fibrillation; predictor model.
Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.