Stroke: Likelihood Ratios

Introduction: aka cerebrovascular accident. Mostly ischemic, some hemorrhagic. CT detects hemorrhagic stroke with high sensitivity. For history/physical findings to distinguish ischemic from hemorrhagic, see Hemorrhagic Stroke.

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Differential Diagnoses include: Neurocardiogenic Syncope

Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
	2.3%
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The likelihood ratios of findings for Stroke are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive and Negative Likelihood Ratios
Finding	Result	+LR	-LR
[ + ] MRI	+ 0 -	inf	0
DWI sequence. Within 6 hours of presentation. Study: Radiology. 2002 Aug;224(2):353-60. PMID: 12147827
[ + ] MRI	+ 0 -	inf	0.4
"conventional", i.e. no DWI sequence. Within 6 hours of presentation. Study: Radiology. 2002 Aug;224(2):353-60. PMID: 12147827

Good Positive Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] Non-contrast Head CT	+ 0 -	4.7	0.6
performed on presentation, or within 6 hours Study: Radiology. 2002 Aug;224(2):353-60. PMID: 12147827

Findings With Unspecified Accuracy
Finding	Result	+LR	-LR
[ + ] Facial nerve paralysis		No accuracy specified.
Study: no study specified.