Abstract
BackgroundThe efficacy and safety of warfarin therapy for stroke prevention in atrial fibrillation (AF) depends on the time in therapeutic range (TTR). We aimed to assess the predictive ability of SAMe-TT2R2 score in Chinese AF patients on warfarin, whose TTR is notoriously poor.Methods and ResultsThis is a single-centre retrospective study. Patients with non-valvular AF on warfarin diagnosed between 1997 and 2011 were stratified according to SAMe-TT2R2 score, and TTR was calculated using Rosendaal method. The predictive power of SAMe-TT2R2 scores for good TTR i.e. >70% was assessed. We included 1,428 Chinese patients (mean age 76.2±8.7 years, 47.5% male) with non-valvular AF on warfarin. The mean and median TTR were 38.2±24.4% and 38.8% (interquartile range: 17.9% and 56.2%) respectively. TTR decreased progressively with increasing SAMe-TT2R2 score (p = 0.016). When the cut-off value of SAMe-TT2R2 score was set to 2, the sensitivity and specificity to predict TTR<70% were 85.7% and 17.8%, respectively. The corresponding positive and negative predictive values were 10.1% and 92.0%. After a mean follow-up of 4.7±3.6 years, 338 patients developed an ischemic stroke (4.96%/year). Patients with TTR≥70% had a lower annual risk of ischemic stroke of 3.67%/year compared with than those with TTR<70% (5.13%/year)(p = 0.08). Patients with SAMe-TT2R2 score ≤2 had the lowest risk of annual risk of ischemic stroke (3.49%/year) compared with those with SAMe-TT2R2 score = 3 (4.56%/year), and those with SAMe-TT2R2 score ≥4 (6.41%/year)(p<0.001). There was also a non-significant trend towards more intracranial hemorrhage with increasing SAMe-TT2R2 score.ConclusionsThe SAMe-TT2R2 score correlates well with TTR in Chinese AF patients, with a score >2 having high sensitivity and negative predictive values for poor TTR. Ischemic stroke risk increased progressively with increasing SAMe-TT2R2 score, consistent with poorer TTRs at high SAMe-TT2R2 scores.
Highlights
Patients with SAMe-TT2R2 score 2 had the lowest risk of annual risk of ischemic stroke (3.49%/year) compared with those with SAMe-TT2R2 score = 3 (4.56%/year), and those with SAMe-TT2R2 score 4 (6.41%/year)(p
The efficacy and safety of warfarin, very much depends on the quality of anticoagulation control, as assessed by the time in therapeutic range (TTR), with the proportion of time spent within therapeutic range of 2.0–3.0.[4,5,6,7] It is generally accepted that patients on warfarin should spend more than 65%, or even 70%, of time with INR between 2–3 to obtain the benefit as well as safety of the therapy.[8, 9]
A new clinical score, the SAMe-TT2R2 score was derived and validated using a primarily white Caucasian population to predict the likelihood of atrial fibrillation (AF) patients on warfarin of having a good TTR.[11]
Summary
Warfarin therapy effectively reduces ischemic stroke and mortality amongst patients with nonvalvular atrial fibrillation (AF).[1,2,3] The efficacy and safety of warfarin, very much depends on the quality of anticoagulation control, as assessed by the time in therapeutic range (TTR), with the proportion of time spent within therapeutic range of 2.0–3.0.[4,5,6,7] It is generally accepted that patients on warfarin should spend more than 65%, or even 70%, of time with INR between 2–3 to obtain the benefit as well as safety of the therapy.[8, 9] In Asian countries, anticoagulation control is notoriously poor, both in real world practice and in randomized clinical trials.[10]Recently, a new clinical score, the SAMe-TT2R2 score was derived and validated using a primarily white Caucasian population to predict the likelihood of AF patients on warfarin of having a good TTR (with SAMe-TT2R2 score 0–2).[11]. Warfarin therapy effectively reduces ischemic stroke and mortality amongst patients with nonvalvular atrial fibrillation (AF).[1,2,3] The efficacy and safety of warfarin, very much depends on the quality of anticoagulation control, as assessed by the time in therapeutic range (TTR), with the proportion of time spent within therapeutic range of 2.0–3.0.[4,5,6,7] It is generally accepted that patients on warfarin should spend more than 65%, or even 70%, of time with INR between 2–3 to obtain the benefit as well as safety of the therapy.[8, 9] In Asian countries, anticoagulation control is notoriously poor, both in real world practice and in randomized clinical trials.[10]. We aimed, for the first time, to evaluate the ability of SAMe-TT2R2 score in predicting the quality of anticoagulation control (as reflected by TTR) in an Asian population. We aimed to assess the predictive ability of SAMe-TT2R2 score in Chinese AF patients on warfarin, whose TTR is notoriously poor
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