CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 8, September 2012
AFRICA
447
factors may influence D-dimer and fibrinogen concentrations.
12-16
Furthermore, in these patients, there was less accessibility to CT
angiography and more complications were experienced with the
use of it.
17,18
The aim of this study was to evaluate the reliability
of the D-dimer:fibrinogen ratio (DDFR) for the diagnosis of PTE
in ICU patients.
Methods
In this analytical cross-sectional study, 91 critically ill patients
admitted to the ICUwards of Rasoul-e-Akram and Shahid-Rajaee
hospitals were included. All of the patients were diagnosed with
diseases such as heart failure, pneumonia and stroke at the time
of hospitalisation. To enrol these patients in our study, they had
to be susceptible to a first PTE in the ICU setting, and showing
signs and symptoms of PTE.
Diagnosis was established by angiography or CT angiography.
The patients with documented PTE were included in our
case group and those without PTE were used as the control
group. Patients with a history of using anticoagulants or oral
contraceptives, and those with a previous history of PTE were
excluded.
Prior to any treatment or invasive diagnostic studies, blood
samples were taken from all patients for routine laboratory
tests such as a complete blood cell count (CBC), arterial blood
gas (ABG), and plasma sodium (Na), potassium (K), D-dimer
and fibrinogen levels. Medical history and other demographic
information were collected from patients’ medical files and
inserted into pre-prepared checklists.
For D-dimer and fibrinogen assays, 2.7 ml of blood was
taken from the antecubital vein of all patients, placed in standard
Vacutainer (Becton Dickinson, Plymouth, UK) tubes containing
0.109
M buffered tri-sodium citrate, and centrifuged at 1 000
×
g
for 10 minutes at 18–21°C to extract the plasma. The samples
were then sent to the laboratory in a cold box.
All biochemical assays were carried out in the clinical
laboratory of Day General Hospital, Tehran, Iran. Functional
fibrinogen level was measured by the Clauss method.
19
D-dimer
level was measured with a Tina-quant D-dimer diagnostic
kit (Roche, Mannheim, Germany) by particle-enhanced
immunoturbidimetric assay with the aid of an automated
chemical analysis system (model 704, Hitachi, Tokyo, Japan).
Intra- and inter-assay coefficients of variance of this test were 6.6
and 1.1%, respectively. In order to calculate DDFR, the equation
below was used:
DDFR
=
D-dimer (
µ
g/ml)
______________
Fibrinogen (mg/dl)
×
100
The study was pre-evaluated and approved by the ethics
committee of the Iran University of Medical Sciences. All
patients or their next of kin were aware of their presence in
the study and verbal or written consent was given. All patients
participated anonymously and their personal information was
kept confidential.
Statistical analysis
All data were entered and analysed by SPSS for Windows
version 16. Qualitative data were expressed as percentages and
quantitative data as means
±
SD. Before the analysis, all data
of quantitative variables were tested for normal distribution
using the Kolmogorov–Smirnov test. Statistical tests such as
the Student’s
t
-
test, Chi-square and Mann–Whitney
U
-
test were
used. For calculating the sensitivity and specificity of various
cut-off points for D-dimer and DDFR levels in this study, a
receiver operating characteristics (ROC) analysis and curve was
conducted. In addition, regression analysis was performed to
create a model to evaluate the risk factors as a predictive test. A
p
-
value
<
0.05
was considered statistically significant.
Results
Baseline characteristics
After excluding 10 patients who did not meet our inclusion
criteria, 81 patients were included in this study; 38 males and
43
females. Mean age was 61.62
±
17.40
years and the mean
duration of hospitalisation was 16.78
±
12.1
days. The most
common cause of admission was cardiovascular disorders (23
patients, 28.3%), pulmonary disease (21 patients, 25.9%) and
neurologic disorders (12 patients, 14.8%). Other causes such
as kidney disease, gastrointestinal bleeding and complications
after orthopaedic surgery were seen in the remaining cases (24
patients, 29.6%).
In their medical history, 27 patients (33.3%) had diabetes
mellitus (DM), 27 (33.3%) had a history of previous cardiac
events (myocardial infarction, unstable angina and other cardiac
problems), 40 (49.5%) had hypertension (HTN), and 20 patients
(24.7%)
had a history of any kind of surgery in the past three
months.
At the end of the study, 41 patients (50.61%) were diagnosed
as definite PTE cases and 40 (49.39%) had a diagnosis other
than PTE and were considered our control group. From the
Chi-square test, a significant difference was seen between
gender percentages in the PTE and non-PTE groups, as 11 of
the 41 (26.8%) PTE-positive patients were males, compared to
23
of 40 (56%) in the PTE-negative group (
p
=
0.001).
Other
characteristics are shown in Table 1.
TABLE 1. BASELINE CHARACTERISTICS OF
THE PATIENTS INCLUDED IN THE STUDY,
DIVIDED BY PATIENTSWITHANDWITHOUT PTE
All patients
(
n
=
81)
With PTE
(
n
=
41)
Without PTE
(
n
=
40)
p
Age (years)
61.62
±
17.40 60.41
±
14.85 61.85
±
20.20 0.867
#
Duration of
hospitalisation (days)
16.78
±
12.10 14.95
±
11.65 19.05
±
12.24 0.154
#
CRP (mg/l)
24.65
±
16.64 21.42
±
18.00 27.11
±
14.22 0.921
#
Temperature (°C)
37.21
±
0.62 36.98
±
0.39 37.46
±
0.75 0.091
#
Systolic BP* (mmHg) 136.21
±
24.96 136.60
±
23.80 136.81
±
26.92 0.980
#
Diastolic BP* (mmHg) 83.81
±
15.01 82.40
±
16.79 85.56
±
12.70 0.538
#
Heart rate (/min)
88.47
±
17.21 91.06
±
16.36 85.56
±
18.19 0.361
#
Respiratory rate (/min) 22.36
±
6.72 22.94
±
7.22 21.67
±
6.24 0.595
#
Sodium (mEq/l)
139.36
±
6.78 141.00
±
7.36 137.58
±
5.88 0.201
#
Potassium (mEq/l)
4.36
±
0.54 4.21
±
0.50 4.54
±
0.55 0.211
$
WBC (/mm
3
)
11.07
±
4.26 3.95
±
1.02 4.22
±
1.09 0.073
#
Haematocrit (%)
37.00
±
7.81 36.28
±
7.49 37.77
±
6.18 0.565
#
pH
7.07
±
0.76 6.84
±
0.96 7.39
±
0.06 0.343
$
PO
2
(
mmHg)
72.63
±
22.68 64.73
±
22.50 79.41
±
21.54 0.258
#
PCO
2
(
mmHg)
45.38
±
17.99 47.76
±
20.69 43.34
±
16.74 0.684
#
HCO
3
(
mEq/l)
27.15
±
10.37 27.05
±
7.69 27.25
±
13.33 0.975
#
*
Blood pressure.
#
From independent samples
t
-
test (for normally distributed variables).
$
From Mann–Whitney U-test (for non-normally distributed variables).
