CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 8, September 2012
446
AFRICA
Accuracy of D-dimer:fibrinogen ratio to diagnose
pulmonary thromboembolism in patients admitted to
intensive care units
SHOKOUFEH HAJSADEGHI, SCOTT R KERMAN, MOJTABA KHOJANDI, HELEN VAFERI, ROZA RAMEZANI,
NEGAR M JOURSHARI, SAYYED AJ MOUSAVI, HAMIDEZAR POURALIAKBAR
Abstract
Introduction:
Pulmonary thromboembolism (PTE) may
increase D-dimer and decrease fibrinogen levels. However, in
settings such as intensive care units (ICU) and in long-term
hospitalised patients, several factors may influence D-dimer
and fibrinogen concentrations and make them unreliable
indicators for the diagnosis of PTE. The aim of this study was
to evaluate the accuracy of D-dimer:fibrinogen ratio (DDFR)
for the diagnosis of PTE in ICU patients.
Methods:
ICU patients who were suspected of having a first
PTE and had no history of using anti-coagulants and contra-
ceptives were included in the study. Levels of D-dimer and
fibrinogen were measured for each patient prior to any inter-
vention. Angiography or CT angiography was done in order
to establish a definite diagnosis for each patient. Suitable
analytical tests were performed to compare means.
Results:
Eighty-one patients were included in the study, of
whom 41 had PTE and 40 did not. Mean values of D-dimer
and fibrinogen were 3.97
±
3.22
µ
g/ml and 560.6
±
197.3
mg/
dl, respectively. Significantly higher levels of D-dimer (4.65
±
3.46
vs 2.25
±
2.55
µ
g/ml,
p
=
0.006)
and DDFR (0.913
±
0.716
vs 483
±
0.440
×
10
-3
,
p
=
0.003)
were seen in PTE patients
than in those without PTE. Receiver operating characteristic
(
ROC) analysis showed a 70.3% sensitivity and 70.1% speci-
ficity with a D-dimer value of 2.43
µ
g/ml (AUC
=
0.714,
p
=
0.002)
as the best cut-off point; and a 70.3% sensitivity and
61.6%
specificity with a DDFR value of 0.417
×
10
-3
(
AUC
=
0.710,
p
=
0.004)
as the best cut-off point. In backward step-
wise regression analysis, DDRF (OR
=
0.72,
p
=
0.025),
gender
(
OR
=
0.76,
p
=
0.049)
and white blood cell count (OR
=
1.11,
p
=
0.373)
were modelled (
p
=
0.029,
R
2
=
0.577).
Conclusion:
For diagnosis of PTE, DDFR can be consid-
ered to have almost the same importance as D-dimer level.
Moreover, it was possible to rule out PTE with only a
D-dimer cut-off value
<
0.43
mg/dl, without the use of DDFR.
However, these values cannot be used as a replacement for
angiography or CT angiography
Keywords:
D-dimer, fibrinogen, pulmonary thromboembolism,
intensive care unit (ICU)
Submitted 3/11/11, accepted 3/5/12
Cardiovasc J Afr
2012;
23
: 446–456
DOI: 10.5830/CVJA-2012-041
Pulmonary thromboembolism (PTE) is the third most common
cause of cardiovascular-related deaths, with an average incidence
of one in 100 000 patients annually.
1,2
PTE is also one of the
most important causes of sudden death and occurs in 10% of
hospitalised patients, of which only 29% are correctly diagnosed
before death.
3
Moreover, PTE is a common life-threatening
complication in patients with long-term hospitalisation,
especially in intensive care units (ICU).
4
The signs and symptoms of PTE are often very non-specific
and can lead the practitioner to misdiagnose it.
5
Although
computed tomographic (CT) angiography is a first-line method
for the diagnosis of PTE, it is contra-indicated in patients with
renal insufficiency and in pregnant women, and it is relatively
expensive, especially for developing countries. These limitations
can result in mismanagement of PTE.
5
Therefore attempts have
been made for years to find a less-invasive, well-priced and more
available test, such as biochemical markers in plasma.
7-10
D-dimer is a degradation product of cross-linked fibrin
that increases in acute thromboembolic events.
11
D-dimer
concentrations can be used to diagnose or rule out PTE but
its specificity is poor because D-dimer levels can be elevated
in other clinical conditions associated with additional fibrin
formation, including old age, malignancies, infections and
postoperative states.
12,13
Plasma fibrinogen is one of the most important factors in
the coagulation cascade and its concentration rises in many
conditions, such as haemodynamic impairment, infections,
cardiac, lung and aortic diseases and malignancies, as an
acute-phase reactant. Many of these conditions have signs and
symptoms similar to those of PTE.
14,15
A study by Kucher
et al
.
demonstrated that the
D-dimer:fibrinogen ratio could be a specific predictor for
PTE in emergency patients with no other medical condition.
9
However, in other settings such as the ICU or in long-term
hospitalised patients with an elevated risk for PTE, several
Department of Cardiology, Rasoul-e-Akram Hospital, Tehran
University of Medical Sciences, Tehran, Iran
SHOKOUFEH HAJSADEGHI, MD
Department of Cardiology, Students Scientific Research
Centre, Tehran University of Medical Sciences, Tehran, Iran
SCOTT R KERMAN, MD, r-jafarian@student.tums.ac.ir
MOJTABA KHOJANDI, MD
HELEN VAFERI
ROZA RAMEZANI
NEGAR M JOURSHARI
Department of Pulmonology, Rasoul-e-Akram Hospital,
Tehran University of Medical Sciences, Tehran, Iran
SAYYED AJ MOUSAVI, MD
Department of Radiology, Shahid Rajaee Heart Hospital,
Tehran University of Medical Sciences, Tehran, Iran
HAMIDEZAR POURALIAKBAR, MD
