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A comparison of three rapid D-dimer methods for the diagnosis
of venous thromboembolism.
Kovacs MJ, MacKinnon KM, Anderson D, O'Rourke K, Keeney M,
Kearon C, Ginsberg J, Wells PS.
Department of Medicine, London Health Sciences Centre, London,
Ontario, Canada.
michael.kovacs@lhsc.on.ca
We
compared three rapid D-dimer methods for the diagnosis of
venous thromboembolism. Patients
presenting to four teaching hospitals with the possible
diagnosis of deep vein thrombosis or
pulmonary embolism were investigated with a combination
of clinical likelihood, D-dimer
(SimpliRED) and initial non-invasive testing. Patients were
assigned as being positive or negative for
deep vein thrombosis or pulmonary embolism based on their
three-month outcome and initial test
results. The three D-dimer methods compared were: (a) Accuclot
D-dimer (b) IL-Test D-dimer (c)
SimpliRED D-dimer. Of 993 patients, 141 had objectively
confirmed deep vein thrombosis or
pulmonary embolism. The sensitivity of SimpliRED, Accuclot
and IL-Test were 79, 90 and 87%
respectively. All three D-dimer tests gave similar negative
predictive values. The SimpliRED
D-dimer was found to be less sensitive than the Accuclot
or IL-Test. When combined with pre-test
probability all three methods are probably acceptable for
use in the diagnosis of venous
thromboembolism.
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| 2 |
Inter-assay
and instrument variability of anti-Xa--results.
Kovacs MJ, Keeney M.
Thromb Haemost 2000 Jul;84(1):138 No Abstract Available
Thromb Haemost. 1999 Oct;82(4):1289-93.
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3
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Three
different chromogenic methods do not give equivalent anti-Xa
levels for patients on therapeutic low molecular weight heparin
(dalteparin) or unfractionated heparin.
Kovacs MJ, Keeney M, MacKinnon K, Boyle E.
Clin Lab Haematol 1999 Feb;21(1):55-60
London Health Sciences Centre, Ontario, Canada.
In this study we compare three chromogenic methods (IL-Heparin,
Stachrom Heparin and Heparin
Sigma) on two different instruments (ACL300+ and AMAX CS190)
for patients on dalteparin (n =
41), a low molecular weight heparin or unfractionated heparin
(n = 50). For dalteparin the mean
anti-Xa levels for IL-Heparin, Stachrom Heparin and Heparin
Sigma were 0.27, 0.30 and 0.21 U/ml,
respectively, while for heparin they were 0.52, 0.55 and 0.41
U/ml, respectively. To test for
instrument specific effects, IL-Heparin and Stachrom Heparin
were repeated on both instruments on
42 patients receiving unfractionated heparin. For IL-Heparin
the mean anti-Xa levels on the AMAX
CS190 and ACL300+ were 0.51 and 0.59 U/ml, respectively, while
for Stachrom Heparin they were
0.55 and 0.67 anti-Xa U/ml. We conclude that different chromogenic
anti-Xa methods do not give
equivalent anti-Xa levels for the same samples. Moreover,
the differences are clinically significant.
This is not explained entirely by instrumentation effects.
Recommended therapeutic ranges may need
to be method and instrument specific.
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| 4 |
Body
weight does not predict for anti-Xa levels after fixed dose
prophylaxis with enoxaparin after orthopedic surgery.
Thromb Res 1998 Aug 1;91(3):137-42
Related Articles, Books, LinkOut
Kovacs
MJ, Weir K, MacKinnon K, Keeney M, Brien WF, Cruickshank
MK.
Department
of Medicine, University of Western Ontario, Canada. michael.kovacs@lhsc.on.ca
Enoxaparin
after joint arthroplasty is effective prophylaxis against
venous thromboembolism. This is
usually given as a fixed dose without monitoring of anti-Xa
levels. This study assesses the
relationship between trough anti-Xa levels, body weight,
and venous thromboembolism. Consenting
patients at three institutions were treated with Enoxaparin
30 mg subcutaneously bis in die
postoperatively until discharge. Chromogenic anti-Xa levels
were measured on the fifth postoperative
day by the method of Stachrome (Diagnostica Stago). All
patients had bilateral compression doppler
ultrasonography on day 10 or discharge and were followed
for 12 weeks for evidence of venous
thromboembolism. Eleven patients developed objectively confirmed
venous thromboembolism during
the study. In this study, there was poor correlation between
weight and anti-Xa levels. In addition,
body weight and anti-Xa levels of patients who developed
venous thromboembolism were compared
to those who did not and there were no significant differences
between the two groups. In conclusion,
this study shows that there is poor correlation of trough
anti-Xa levels with body weight. Recognizing
the low overall event rate this study does not support the
need to monitor anti-Xa levels or adjusting
the dose according to weight.
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| 5 |
Assessment
of the validity of the INR system for patients with liver impairment.
Thromb
Haemost 1994 Jun;71(6):727-30, Thromb Haemost. 1995 Jan;73(1):162.
Kovacs
MJ, Wong A, MacKinnon K, Weir K, Keeney M, Boyle E, Cruickshank
M.
Department
of Hematology/Blood Bank, Victoria Hospital, London, Ontario,
Canada.
The INR
system was developed to standardize PT reporting in patients
on oral anticoagulants. We
prospectively collected blood samples from 29 patients with
liver impairment (INR 1.5-3.5). Control
patients were on warfarin (n = 31). PT's were measured on
an ACL-300 with three thromboplastin
reagents. INR's were calculated using instrument specific
ISI's. Other tests performed were FDP's,
fibrinogen, aPTT, factors II, V, VII and X. The INR's for
each patient in the study population using the
three thromboplastin reagents were significantly different
(p = 0.0001). Those for the control
population were not (p = 0.0658). Fibrinogen, factors V, II
and X were different at the 5% level of
significance between the populations. FDP's were detected
in 17 study subjects. The INR system is
not valid for comparison of patients with liver impairment
because different reagents do not give the
same INR for the same sample. It is, however, no less valid
than the use of PT with different
thromboplastin reagents. Further study is recommended.
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| 6 |
Decreasing
liver biopsy complications.
Ann
Intern Med 1993 Sep 1;119(5):436; discussion 436-7
Ann Intern Med. 1993 Jan 15;118(2):149-50
Ann Intern Med. 1993 Jan 15;118(2):96-8.
Kovacs MJ, Keeney M, Chin-Yee I.
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Revised:
March 23, 2005 7:49 AM
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