Utility of an initial D-dimer assay in screening
for traumatic or spontaneous intracranial hemorrhage.
Hoffmann ME, Ma OJ, Gaddis
G.
Department of Emergency Medicine, Truman Medical Center,
University of Missouri-Kansas City School of Medicine, Kansas City, MO,
USA. crazydiamond@aol.com
OBJECTIVE: To evaluate the sensitivity
of a D-dimer assay as a screening tool for possible traumatic or
spontaneous intracranial hemorrhage. If adequately sensitive, the
D-dimer assay may potentially permit omission of a more expensive
computed tomography (CT) scan of the head when such hemorrhage is
clinically suspected. METHODS: Prospective, consecutive, blinded study
of patients (age > 16 years) requiring a CT scan of the head for
suspected intracranial hemorrhage over a five-month period at a
university, Level I trauma center. All study patients had a serum
D-dimer assay obtained prior to their CT scans. Sensitivity and
specificity, with 95% confidence intervals (95%
CIs), of the
enzyme-linked immunosorbent assay (ELISA) D-dimer assay for the
detection of intracranial hemorrhage were calculated. RESULTS: Of the
319 patients entered in the study, 25 (7.8%) had a CT scan positive for
intracranial hemorrhage. Patients with intracranial hemorrhage were more
likely to have a positive D-dimer assay (chi-square = 13.075, p <
0.001). The D-dimer assay had 21 true-positive and four false-negative
tests, resulting in a sensitivity of 84.0% (95% CI = 63.7% to 95.5%) and
a specificity of 55.8% (95% CI = 55.5% to 55.9%). The four
false-negative cases included one small intraparenchymal hemorrhage, one
small subarachnoid hemorrhage, one moderate-sized intraparenchymal
hemorrhage with mid-line shift, and one large subdural hematoma
requiring emergent surgery. CONCLUSIONS: Due to the catastrophic nature
of missing an intracranial hemorrhage in the emergency department, the
D-dimer assay is not adequately sensitive or predictive to use as a
screening tool to allow routine omission of head CT scanning.
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