CLINICAL NEWS
Assessing the Updated Vienna
Prediction Model for Unprovoked
VTE: Does It Hold Up?
The Vienna Prediction Model was
established to identify patients
with unprovoked venous thromboembolism (VTE) who have a low
risk of recurrence, with the aim of
avoiding unnecessary anticoagulant
therapy. In validation tests, though,
the model showed a “less than optimal calibration, underestimating
the observed cumulative recurrence
rates at 12 months,” according to
Tobias Tritschler, MD, from the
Department of General Internal
Medicine at Bern University Hospital in Switzerland.
“Given that one-third of the
patients with unprovoked VTE
have a low recurrence risk and
may stop anticoagulation therapy
after three months, a risk stratification tool to identify these patients
is important,” Dr. Tritschler told
ASH Clinical News.
Recently, the original developers of the model published an
updated version to address these
concerns. Unlike the original version, the updated model allows for
prediction of recurrence at several
different time points after stopping
anticoagulation (3 weeks and 3, 9,
15, and 24 months). However, in a
study recently published in Blood,
Dr. Tritschler and co-authors
discovered that the updated model
still leaves something to be desired.
The original Vienna Prediction Model was devised through
a prospective cohort study of 929
patients with a first unprovoked
VTE, and assigned risk based on
the following three parameters:
• Sex
• Location of VTE (pulmonary
embolism [PE]/proximal deep
vein thrombosis [DVT] vs. distal
DVT)
• Quantitative D-dimer level
determined by ELISA between
three weeks and 15 months
after discontinuation of
anticoagulation
The updated version was developed in a prospective cohort of
553 patients with unprovoked
VTE and uses the same clinical
parameters as the original model
to estimate recurrent VTE risk
at up to 60 months of follow-up
using nomograms or a Web-based
calculator.
ASHClinicalNews.org
TABLE 3.
Patient Baseline Characteristics
Low-risk patients
(n=39)
All (N=156)
Higher-risk patients
(n=117)
Age (years)
Male sex
74.0 (69.0; 79.8)
73.0 (68.0; 77.0)
75.0 (69.0; 80.0)
0.27
92 (59)
4 (10)
88 (75)
<0.01
The current multicenter study attempts
137 (88)
28 (72)
109 (93)
PE and/or proximal DVT
to validate the updated
1022 (607; 1755)
717 (410; 1016)
1,161 (694; 1,913)
D-dimer (ng/ml)
model included 156
27.5 (24.8; 30.5)
27.7 (24.9; 31.9)
27.5 (24.8; 30.4)
BMI (kg/m2)
patients ≥65 years old
23 (15)
8 (21)
15 (13)
Prior VTE
with acute symptomatic
unprovoked VTE from
Time since stopping anti5.7 (4.9; 6.9)
5.9 (5.0; 7.6)
5.6 (4.7; 6.6)
coagulation (months)
nine Swiss hospitals.
Patients were excluded
Duration of prior antico6.3 (5.3; 7.1)
6.0 (4.1; 6.9)
6.4 (5.5; 7.2)
agulation (months)
from the study if they
were immobile, had major
surgery, were taking oral
estrogen therapy, or had active
≥1022 ng/mL had recurrent VTE, updated Vienna Prediction Model
cancer during the previous three
compared with 15% of patients
was developed in patients with a
months. All patients had completwith a D-dimer <1022 ng/mL
broader age distribution. Ultied a three- to 12-month course of
(p=0.83)
mately, it is still too soon to make
anticoagulation.
any treatment recommendations
Study participants had a
Ultimately, the updated Vienna
based on this risk prediction tool,
median age of 74 years, 41 percent
Prediction Model failed to corthe authors added.
were female and 88 percent had
rectly identify patients as low- or
“The updated Vienna PredicPE or proximal DVT as the initial
high-risk for recurrent VTE. “The
tion Model does not allow the
VTE event (TABLE 3).
proportion of recurrent VTE did
identification of elderly patients at
not differ between low- versus
low risk of VTE recurrence who
To validate the updated model,
higher-risk patients at 12 months
may stop anticoagulation therapy
Dr. Tritschler and colleagues
(13% vs. 10%, respectively;
after three months,” Dr. Tritschler
determined the proportion of
p=0.77) and 24 months (15% vs.
said. “A risk stratification tool that
patients classified as low-risk
17%, respectively; p=1.0),” the
accurately identifies elderly paaccording to the updated Vienna
authors reported.
tients with unprovoked VTE who
Prediction Model and compared
Limitations of the study
are at low risk of VTE recurrence
the proportion of VTE recurrence
include the relatively small sample
is still needed.”
between low- and higher-risk
size, and that the study may have
patients at 12 and 24 months.
REFERENCE
been underpowered to detect a
In the updated model, they
Tritschler T, Mean M, Limacher A, et al. Predicting
difference in VTE recurrence.
noted, patients with a predicted
recurrence after unprovoked venous thromboembolism:
The study also focused on older
12-month risk <6.2 percent are
prospective validation of the updated Vienna Prediction
patients with VTE, whereas the
classified as “low risk.”
Model. Blood. 2015 September 4. [Epub ahead of print]
Overall, the proportion of VTE
recurrence was 11 percent (17 of
156 patients) after 12 months and
17 percent (26 of 156) after 24
months. At 12 months:
• 5% of men had recurrent VTE
compared with 19% of women
(p=0.02)
• 11% of patients with both PE/
proximal DVT and distal DVT
had recurrent VTE (p=1.0)
• 13% of patients with a D-dimer
≥1022 ng/ml had recurrent VTE,
compared with 9% of those with a
D-dimer <1022 ng/mL (p=0.61)
At 24 months:
• 12% of men and 23% of women
had recurrent VTE (p=0.08)
• 17% of patients with PE/proximal
DVT and 16% of patients with
distal DVT had recurrent VTE
(p=1.0)
• 18% of patients with a D-dimer
p Value
n (%) or median (interquartile range)
<0.01
<0.01
0.44
0.30
0.20
0.20
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