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Inadequacy of clinical scoring systems to differentiate stroke subtypes in population-based studies
G C Hawkins1, R Bonita, J B Broad
1Department of Community Health, University of Auckland, New Zealand.
Background And Purpose:
We undertook to examine the usefulness for epidemiological studies of two well-known validated clinical scoring methods, the Guys' Hospital Stroke score and the Siriraj Hospital Stroke score, to classify strokes into the two main types, hemorrhagic and ischemic, in epidemiological studies.
Methods:
Patients from a population-based stroke register who received either a CT scan or an autopsy were retrospectively scored using the two clinical scoring methods. The scores were then compared with the CT scan and autopsy results to determine the sensitivity, specificity, and positive predictive value for intracranial hemorrhage (primary intracerebral and subarachnoid hemorrhage) and ischemic stroke.
Results:
Over a 12-month period, 554 patients from a population-based study underwent CT scanning. Films or autopsy reports were available for 521 patients, and of these, sufficient clinical information to calculate the Guys' Hospital Stroke score and the Siriraj Hospital Stroke score was available for 464 and 475 patients, respectively. For the Guys' Hospital Stroke score, the sensitivity and specificity for intracranial hemorrhage were 31% and 95%, respectively; the positive predictive value was 73%. The sensitivity and specificity for ischemic stroke were 78% and 70%, respectively, and the positive predictive value was 86%. For the Siriraj Hospital Stroke score, the sensitivity and the specificity for intracranial hemorrhage were 48% and 85%, respectively; the positive predictive value was 59%. The sensitivity and specificity for ischemic stroke were 61% and 74%, respectively, and the positive predictive value was 84%.
Conclusions:
This validation study suggests that both clinical scores lack sufficient validity to be used in epidemiological studies for classification of stroke types and should probably not be used in the randomization of patients into treatment trials using thrombolytic or antithrombotic drugs in the absence of diagnostic information based on neuroimaging techniques.