![Inferiority of International Normalized Ratio Compared to Thrombelastography in Coagulopathy
Assessment: an Examination of Correlation with Factor Levels and Thrombin Generation in
Trauma Patients
Julia R Coleman MD MPH, Ernest E Moore MD, Saulius Butenas PhD, Alexander Olson BS,
Mitchell J Cohen MD, Arthur Colvis BS, Arsen Ghasabyan MPH, James Chandler, Megan L
Swope BA, Christopher C Silliman MD PhD
Introduction:
The utility of conventional coagulation assays, such as international normalized ratio (INR), for
assessing coagulopathy in severely injured patients has been questioned. This is particularly true
in the setting of discordant results against thrombelastography (TEG). We hypothesize that an
elevated INR will not confer depressed factor levels or thrombin generation (TG) in the setting
of normal TEG (normal activating clotting time, angle, maximum amplitude [MA], and lysis 30
minutes after MA).
Methods:
Six patients with an elevated INR (>1.5, confirmed on second measurement) and normal TEG
were matched with six patients with a normal INR (≤1.5) and normal TEG by age, sex and
indicators of shock and tissue injury. Using blood collected immediately upon presentation
following injury, percent factor level II, V, VII, VIII, X and XII activity level and IXa and XIa
levels as well as TG were measured with the Stago STA Compact Max and BioTek CAT.
Results
There were no differences in factor II, V, VII, VIII, X or XII % activity level or IXa and XIa
levels between patients with a normal versus elevated INR (Table 1). There were also no
differences in TG measurements between groups, specifically lag time, peak IIa, time to peak
thrombin, max rate or area under the curve.
Conclusions:
These data suggest INR is a poor assessment of coagulopathy and an elevated INR in a patient
with normal TEG measurements should be interpreted with caution.
Table 1. Factors levels and TG in patients with an elevated INR and normal TEG matched to patients with
a normal INR and normal TEG
Normal INR, ≤ 1.5
(n=6)
Elevated INR, > 1.5
(n=6) p value
Factor II, median % (25-75
IQR) 84 (42-108) 65 (54-85) 0.59](https://image.slidesharecdn.com/acsabstract-190827194335/85/Inferiority-of-International-Normalized-Ratio-Compared-to-Thrombelastography-in-Coagulopathy-Assessment-an-Examination-of-Correlation-with-Factor-Levels-and-Thrombin-Generation-in-Trauma-Patients-1-320.jpg)
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Inferiority of International Normalized Ratio Compared to Thrombelastography in Coagulopathy Assessment: an Examination of Correlation with Factor Levels and Thrombin Generation in Trauma Patients
- 1. Inferiority of International Normalized Ratio Compared to Thrombelastography in Coagulopathy Assessment: an Examination of Correlation with Factor Levels and Thrombin Generation in Trauma Patients Julia R Coleman MD MPH, Ernest E Moore MD, Saulius Butenas PhD, Alexander Olson BS, Mitchell J Cohen MD, Arthur Colvis BS, Arsen Ghasabyan MPH, James Chandler, Megan L Swope BA, Christopher C Silliman MD PhD Introduction: The utility of conventional coagulation assays, such as international normalized ratio (INR), for assessing coagulopathy in severely injured patients has been questioned. This is particularly true in the setting of discordant results against thrombelastography (TEG). We hypothesize that an elevated INR will not confer depressed factor levels or thrombin generation (TG) in the setting of normal TEG (normal activating clotting time, angle, maximum amplitude [MA], and lysis 30 minutes after MA). Methods: Six patients with an elevated INR (>1.5, confirmed on second measurement) and normal TEG were matched with six patients with a normal INR (≤1.5) and normal TEG by age, sex and indicators of shock and tissue injury. Using blood collected immediately upon presentation following injury, percent factor level II, V, VII, VIII, X and XII activity level and IXa and XIa levels as well as TG were measured with the Stago STA Compact Max and BioTek CAT. Results There were no differences in factor II, V, VII, VIII, X or XII % activity level or IXa and XIa levels between patients with a normal versus elevated INR (Table 1). There were also no differences in TG measurements between groups, specifically lag time, peak IIa, time to peak thrombin, max rate or area under the curve. Conclusions: These data suggest INR is a poor assessment of coagulopathy and an elevated INR in a patient with normal TEG measurements should be interpreted with caution. Table 1. Factors levels and TG in patients with an elevated INR and normal TEG matched to patients with a normal INR and normal TEG Normal INR, ≤ 1.5 (n=6) Elevated INR, > 1.5 (n=6) p value Factor II, median % (25-75 IQR) 84 (42-108) 65 (54-85) 0.59
- 2. Factor V, median % (25-75 IQR) 64 (37-104) 62 (47-94) 0.98 Factor VII, median % (25-75 IQR) 87 (46-110) 77 (48-94) 0.90 Factor VIII, median % (25-75 IQR) 328 (244-378) 208 (77-292) 0.08 Factor X, median % (25-75 IQR) 79 (53-102) 76 (60-108) 0.85 Factor IXa (pM) 5.0 (1.0-9.3) 3.2 (1.0-10.5) 0.84 Factor XIa (pM) 23.5 (0.0-93.0) 54.0 (0.0-73.5) 0.91 Factor XII, median % (25-75 IQR) 99 (65-128) 100 (78-178) 0.39 TG: Lag time (s) 947.5 (743.3- 1570.0) 1109.0 (757.5- 1565.0) 0.95 TG: Peak IIa (nM) 338.5 (152.5-380.5) 307.6 (252.2-385.1) 0.62 TG: Max rate (nM/s) 2.46 (1.71-3.14) 2.96 (2.37-3.68) 0.19