A prospective validation of the SAME-TT2R2 score: How to identify atrial fibrillation patients who will have good anticoagulation control on warfarin

Article (PDF Available)inInternal and Emergency Medicine 9(4) · March 2014with317 Reads
DOI: 10.1007/s11739-014-1065-8 · Source: PubMed
Abstract
Stroke prevention, achieved with oral anticoagulation therapy (OAT), is central to the management of patients with atrial fibrillation (AF). Well-managed OAT, as reflected by a long time in therapeutic range (TTR), is associated with good clinical outcomes. The SAME-TT2R2 score has been proposed to identify patients who will maintain a high average TTR on vitamin K antagonists (VKA) treatment. The objective of the study was to validate this score in a cohort of AF patients followed by an anticoagulation clinic. We applied the SAME-TT2R2 score to 1,089 patients with AF on VKAs followed by two anticoagulation clinics. The median TTR overall for the whole cohort was 73.0 %. There was a significant decline in mean (or median) TTR in relation to the SAME-TT2R2 score (p = 0.042). When the SAME-TT2R2 scores were categorized we find a TTR 74.0 % for score ≤2 and 68.0 % for score >2 (p = 0.006). The rate of major bleeding events and stroke/TIA was 1.78 × 100 patient-years (pt-yrs) and 1.26 × 100 pt-yrs, respectively. No relationship exists between the SAME-TT2R2 score and adverse events. We describe the first validation of the SAME-TT2R2 score in AF patients where, despite an overall good quality of anticoagulation, the SAME-TT2R2 score is able to identify the patients who are less likely to do well on VKA therapy if this is the chosen OAT.
IM - ORIGINAL
A prospective validation of the SAME-TT
2
R
2
score:
how to identify atrial fibrillation patients who will have good
anticoagulation control on warfarin
Daniela Poli
Emilia Antonucci
Sophie Testa
Gregory Yoke Hong Lip
Received: 25 November 2013 / Accepted: 20 February 2014
Ó SIMI 2014
Abstract Stroke prevention, achieved with oral antico-
agulation therapy (OAT), is central to the management of
patients with atrial fibrillation (AF). Well-managed OAT,
as reflected by a long time in therapeutic range (TTR), is
associated with good clinical outcomes. The SAME-TT
2
R
2
score has been proposed to identify patients who will
maintain a high average TTR on vitamin K antagonists
(VKA) treatment. The objective of the study was to vali-
date this score in a cohort of AF patients followed by an
anticoagulation clinic. We applied the SAME-TT
2
R
2
score
to 1,089 patients with AF on VKAs followed by two
anticoagulation clinics. The median TTR overall for the
whole cohort was 73.0 %. There was a significant decline
in mean (or median) TTR in relation to the SAME-TT
2
R
2
score (p = 0.042). When the SAME-TT
2
R
2
scores were
categorized we find a TTR 74.0 % for score B2 and 68.0 %
for score [2(p = 0.006). The rate of major bleeding
events and stroke/TIA was 1.78 9 100 patient-years (pt-
yrs) and 1.26 9 100 pt-yrs, respectively. No relationship
exists between the SAME-TT
2
R
2
score and adverse events.
We describe the first validation of the SAME-TT
2
R
2
score
in AF patients where, despite an overall good quality of
anticoagulation, the SAME-TT
2
R
2
score is able to identify
the patients who are less likely to do well on VKA therapy
if this is the chosen OAT.
Keywords Atrial fibrillation Vitamin K antagonist
Oral anticoagulant therapy TTR
Introduction
Stroke prevention is central to the management of patients
with atrial fibrillation (AF), and effective stroke prevention
is essentially achieved with oral anticoagulation therapy
(OAT). Current Guidelines [1] recommend that the initial
decision step should be to identify any ‘low risk’ patients
who do not need any antithrombotic therapy [13]. Fol-
lowing this initial step, effective stroke prevention
(essentially OAT) should be offered to those patients with
C1 stroke risk factors. OAT has been traditionally given as
vitamin K antagonists (VKA, e.g., warfarin), but in the last
few years novel oral anticoagulants (NOACs), e.g., da-
bigatran, rivaroxaban and apixaban, have become available
for clinical use, changing the landscape for stroke pre-
vention in AF. Indeed, NOACs have yielded encouraging
results, showing at least noninferiority to warfarin for
efficacy and safety. On the other hand, it is known that
efficacy and safety of VKAs is closely dependent upon the
amount of time in therapeutic range (TTR), with maximum
benefits when the TTR is greater than 70 % [46]. Well-
managed OAT, as reflected by a high TTR is associated
with good clinical outcomes in relation to stroke prevention
along with minimized risks of bleeding [5, 7, 8]. Where the
D. Poli (&)
Department of Heart and Vessels, Thrombosis Centre,
Azienda Ospedaliero-Universitaria Careggi,
Viale Morgagni, 85, 50134 Florence, Italy
e-mail: polida@aou-careggi.toscana.it
E. Antonucci
Department of Experimental and Clinical Medicine,
University of Florence, Florence, Italy
S. Testa
Haemostasis and Thrombosis Centre,
A O Istituti Ospitalieri di Cremona, Cremona, Italy
G. Y. H. Lip
Centre for Cardiovascular Sciences, City Hospital,
University of Birmingham, Birmingham B18 7QH, UK
123
Intern Emerg Med
DOI 10.1007/s11739-014-1065-8
average TTR is high, the magnitude of gain from dabiga-
tran over warfarin for the reduction of stroke and systemic
embolism may be small [9]. Recently, comparable results
were reported in similar analysis comparing apixaban and
warfarin, even if the superiority of apixaban is maintained
across all quartiles of TTR [10]. An important clinical
dilemma when faced with a new patient with AF who
needs OAT is deciding upfront who will do well on VKAs
with good anticoagulation control (with a high average
TTR), as opposed to those likely to do badly (with poor
TTR) such that an NOAC would be a better choice.
In 2013, Apostolakis et al. [11] validated the SAME-
TT
2
R
2
score, based on simple clinical features that would
provide an easy means to predict those who would do well
on VKA (SAME-TT
2
R
2
score 0–1), opposed to those likely
to have poor anticoagulation control (SAME-TT
2
R
2
score
C2) where an NOAC might be tried instead. The SAME-
TT
2
R
2
score had good predictive value in the initial deri-
vation and validation cohorts, but further prospective val-
idation in an independent cohort was necessary. In the
present analysis, we present the first independent validation
of the SAME-TT
2
R
2
score in a cohort of patients referred
for OAT.
Methods
We prospectively studied 1,089 patients with AF referred
for the control of OAT to the Thrombosis Centres of Az-
ienda Ospedaliero-Universitaria Careggi, Florence, Tus-
cany Region, and of Cremona Hospital, Lombardia Region.
Both Centres are anticoagulation clinics. They manage the
anticoagulation treatment of ambulatory patients: 1,800
patients in Florence and 4,500 in Cremona. All patients
were treated with warfarin, and the international normal-
ized ratio (INR) was maintained at the intended therapeutic
range of 2.0–3.0. The quality of anticoagulation was cal-
culated as TTR using the linear interpolation method of
Rosendaal et al. [12]; this calculation started at the
beginning of treatment. In the whole cohort of 1,016/1,089
patients (93.3 %) were VKA naı
¨
ve. Patients’ demographic
and clinical data were collected. The presence of traditional
cardiovascular risk factors and other characteristics asso-
ciated with thromboembolic complications in AF were
assessed on the basis of patients’ interviews and hospital
records. Patients were classified as hypertensive if they
were taking medications to lower blood pressure. Diabetes
mellitus was defined according to American Diabetes
Association criteria. Coronary artery disease was defined
on the basis of a history of myocardial infarction, or stable
and unstable angina. Heart failure was defined as the pre-
sence of signs and symptoms of either right or left ven-
tricular failure or both, confirmed by noninvasive or
invasive measurements demonstrating objective evidence
of cardiac dysfunction.
Follow-up visits were scheduled every 2–4 weeks for
INR monitoring. Hospital admissions, concomitant thera-
pies, intercurrent illnesses, bleeding, and thrombotic events
during follow-up were recorded. Patients who missed
checkups for [2 months were contacted (personally or
through their family or general practitioner), and the reason
for interrupting treatment monitoring was recorded. In the
case of death, further information about its cause was
requested. When this information was lacking, national
register of causes of death and autopsy results (if avail-
able), were consulted.
Data collection ceased after the occurrence of stroke or
TIA or major bleeding, after the cessation of OAT, or when
the patient stopped being monitored by our Anticoagula-
tion Clinics. Stroke was defined as a syndrome character-
ized by rapidly developing clinical symptoms and signs of
focal and, at times, global loss of brain function lasting
24 h, not explained by other causes and in the absence of
primary hemorrhage. Ischemic stroke was defined as a
stroke with either a normal brain CT scan or evidence of a
recent infarction in the clinically relevant area of the brain
on a CT scan or MRI scan within 3 weeks of the event, and
previous TIA was diagnosed when neurologic defects las-
ted 24 h. Bleeding was classified as ‘major’ when it was
fatal, intracranial (documented by imaging), ocular causing
blindness, articular, or retroperitoneal; when surgery or
transfusion of more than two blood units was required; or
when the hemoglobin level was reduced by more than
2 g/dL.
The recently published SAME-TT
2
R
2
score [11] was
applied to the database to evaluate its possibility of pre-
dicting poor INR control. The score considered six items
with a maximum score of eight points (see Table 1). The
Table 1 The SAME-TT
2
R
2
score
Acronym Definitions Points
S Sex (female) 1
A Age (less than 60 years) 1
ME Medical history
a
1
T Treatment (interacting Rx,
e.g., amiodarone for rhythm control)
1
T Tobacco use (within 2 years) 2
R Race (non-Caucasian) 2
Maximum points
b
8
The table reports the description of the items considered by the score
a
Two of the following: hypertension, diabetes, myocardial infarc-
tion, peripheral artery disease, congestive heart failure, previous
stroke, pulmonary disease, hepatic or renal disease
b
In our population all patients are Caucasian, therefore the maximum
score is 6
Intern Emerg Med
123
calculation is made on four items giving one point for sex
(female), age \60, medical history ([2 for the following
comorbidities: hypertension, diabetes, coronary artery dis-
ease/myocardial infarction, peripheral arterial disease,
congestive heart failure, previous stroke, pulmonary dis-
ease, hepatic or renal disease), treatment strategy (inter-
acting drugs, e.g., amiodarone for rhythm control), and two
points for: either tobacco use and race (non-caucasian).
Based on a European consensus [4], an average TTR of
C70 % would be the cut-off criterion for ‘good anticoag-
ulation control’. Based on the first derivation and validation
cohorts [11], we categorized a SAME-TT
2
R
2
score 0–1 as
likely to have good TTR control, SAME-TT
2
R
2
score = 2
as ‘borderline’ and SAME-TT
2
R
2
score [2 as likely to
have poor TTR control (\70 %).
The study has been performed in accordance with the
Declaration of Helsinki.
Statistical analysis
We used descriptive analysis expressed as median and
inter-quartile range (IQR) for continuous variables. Fol-
lowing a test of statistical normality, analyses were per-
formed using the Fisher exact test. The comparison among
TTR values obtained at various levels of SAME-TT
2
R
2
score was performed by using the Kruskal–Wallis test.
Incidence rates of adverse events were calculated as the
number of events per 100 patient-years (pt-yrs) of obser-
vation. For this calculation, observation started at the
beginning of follow-up, and ended when patients experi-
enced a major outcome or were finished. A two-sided value
of p \ 0.05 was chosen for statistical significance. We used
the SPSS statistical software package (software for Win-
dows, version 19, Statistical Package for Social Sciences,
Chicago, IL) for data processing.
Results
We studied 1,089 patients with AF (37.8 % female; median
age 75 years), all Caucasian, who were followed up for
4.6 years (Table 2). The average CHADS2 score was
2.2 ± 1.3 and CHA2DS2-VASc score was 3.7 ± 1.6. The
mean and median TTR overall for the whole cohort was
good, being 71.5 and 73.0, respectively. The mean and
median TTRs in relation to SAME-TT
2
R
2
scores 0–1, 2 and
[2 are shown in Table 3. There was a significant decline
in mean (or median) TTR in relation to the SAME-TT
2
R
2
score (p = 0.042). When the SAME-TT
2
R
2
scores were
categorized as B2 and [2, there was again a clear differ-
ence between low to high SAME-TT
2
R
2
scores
(p = 0.006). During follow-up, we recorded 88 major
bleeding events (rate 1.78 9 100 pt-yrs) and 63 stroke/TIA
(rate 1.26 9 100 pt-yrs). There was no relationship
between the SAME-TT
2
R
2
score and bleeding events or
stroke/TIA (data not shown).
Discussion
In this study, we applied the SAME-TT
2
R
2
score to a
population of AF patients followed in anticoagulation
clinics, and we show that a score B2 is predictive of a good
TTR, while a SAME-TT
2
R
2
of[2 is associated with lower
TTRs. Determinants of the TTR can be multifactorial, and
can include the method and intensity of monitoring, self-
monitoring or hospital based, and clinic setting (hospital
specialized clinic vs. community-managed) [13]. Never-
theless, when a patient initially commences warfarin ther-
apy, it is difficult to predict in daily practice if he/she will
be able to achieve and maintain a good INR control. The
SAME-TT
2
R
2
score was proposed as a simple score for use
in everyday clinical practice to aid decision-making on
choice of the best anticoagulant treatment. Indeed, the
therapeutic options now available for AF patients require a
Table 2 Clinical characteristics of patients
N (%) 1,089
Females (%) 412 (37.8)
Median age (range) 75 (30–94)
Age \60 years 61 (5.6)
Follow-up period (years) 4,967
Mean follow-up (years) (SD) 4.6 (3.7)
Past medical history (%) 563 (51.8)
Heart failure 268 (24.7)
Hypertension 745 (68.7)
Diabetes 216 (19.9)
Coronary artery disease 239 (22.1)
Peripheral artery disease 143 (13.2)
Previous stroke/TIA 313 (28.8)
Smoking habits 181 (16.6)
Time in TR % (IQR) 73 (62.5–82.0)
Time below TR (IQR) 12 (6.0–20.0)
Time above TR (IQR) 12 (7.0–19.0)
5th TTR percentile 43.0
10th TTR percentile 52.0
Treatment
Amiodarone 200 (18.4)
Beta blockers 277 (25.4)
Aspirin 64 (5.9)
In the table are listed the demographic and clinical characteristics of
patients
Data are expressed as n (%), mean (SD) or median (IQR)
SD standard deviation, IQR inter-quartile range, TR therapeutic range
Intern Emerg Med
123
way to predict who would better benefit from VKAs, or
from the use of NOACs.
In patients treated with VKAs, the quality of anticoag-
ulation evaluated by measure of the TTR varies widely,
and it is known that maintaining high TTR levels is asso-
ciated with good outcomes in relation to stroke-free prog-
nosis [5, 14]. In the meta-analysis by Wan et al. [6], high
average TTR is associated with low stroke and bleeding
events. However, in our study there was no relationship of
the SAME-TT
2
R
2
score to bleeding or stroke/TIA. It
should be noted that the mean TTR of our cohort is ele-
vated, with low rates of bleeding and stroke/TIA recorded.
While we find no relation to bleeding or stroke/TIA, our
modest sample size and the low rate of adverse events
precludes definitive conclusions, and larger studies are
needed to ascertain the relationship to OAT outcomes.
This study is limited by its dependence upon specialized
clinics for VKAs treatment monitoring, since the overall
mean or median TTR for the whole cohort was very good.
As a matter of fact, only 16 % of patients had a SAME-
TT
2
R
2
score of [2. Further studies are needed in other
patient cohorts with a wider spread of SAME-TT
2
R
2
scores, and with an overall poorer quality of anticoagula-
tion control (low centre average TTR) to investigate the
discriminating value of the SAME-TT
2
R
2
scores 0–1, 2 and
[2 in such settings.
In conclusion, we describe the first validation of the
SAME-TT
2
R
2
score in two anticoagulation clinics, where
despite an overall good quality of anticoagulation, the
SAME-TT
2
R
2
score was able to identify the patients who
were less likely to do well on VKA therapy if this were the
chosen OAT.
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Table 3 Time in therapeutic range (TTR) in relation to SAME-
TT
2
R
2
score
N TTR
Median (%)
IQR TTR Mean
(±SD) (%)
p value
SAME-TT
2
R
2
score
0 189 74.0 62.5–83.5 71.9 (16.9)
1 435 74.0 64.0–83.0 72.4 (14.6)
2 288 74.0 63.0–82.7 72.0 (15.6)
3 127 70.0 60.0–81.0 68.5 (16.9)
4 44 67.5 60.0–81.0 68.4 (15.7)
5 5 62.0 51.0–74.0 62.6 (13.5)
6 1 52.0 NA NA 0.042
Categorized SAME-TT
2
R
2
score
0–1 624 74.0 63.0–83.0 72.3 (15.3)
2 288 74.0 63.0–83.0 72.0 (15.6)
[2 177 68.0 59.0–80.0 68.2 (16.4) 0.006*
Total 1,089 73.0 62.5–82.0 71.5 (15.6)
In the table are reported median and mean TTR in relation to the
different SAME-TT
2
R
2
scores and after categorizing the score
* p value score [2 vs. B2
Intern Emerg Med
123
11. Apostolakis S, Sullivan RM, Olshansky B, Lip GY (2013) Fac-
tors affecting quality of anticoagulation control amongst atrial
fibrillation patients on warfarin: the SAME-TT2R2 (sex female,
age less than 60, medical history, treatment strategy (rhythm
control), tobacco use (doubled), race (doubled) score. Chest
144:1555–1563
12. Rosendaal FR, Cannegieter SC, van der Meer FJM, Briet E
(1993) A method to determine the optimal intensity of oral
anticoagulant therapy. Thromb Haemost 69:236–239
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R, Yang S, Kabali C, Reilly PA, Ezekowitz MD, Connolly SJ
(2012) Variation in warfarin dose adjustment practice is
responsible for differences in the quality of anticoagulation
control between centers and countries: an analysis of patients
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