title: External validation of the Practical Risk Chart for the prediction of delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage.
abstract: OBJECTIVE Delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) occurs in approximately 30% of patients. The Practical Risk Chart was developed to predict DCI based on admission characteristics; the authors seek to externally validate and critically appraise this prediction tool. METHODS A prospective cohort of aSAH patients was used to externally validate the previously published Practical Risk Chart. The model consists of 4 variables: clinical condition on admission, amount of cisternal and intraventricular blood on CT, and age. External validity was assessed using logistic regression. Model discrimination was evaluated using the area under the receiver operating characteristic curve (AUC). RESULTS In a cohort of 125 patients with aSAH, the Practical Risk Chart adequately predicted DCI, with an AUC of 0.66 (95% CI 0.55-0.77). Clinical grade on admission and amount of intracranial blood on CT were the strongest predictors of DCI and clinical vasospasm. The best-fit model used a combination of the Hunt and Hess grade and the modified Fisher scale to yield an AUC of 0.76 (95% CI 0.675-0.85) and 0.70 (95% CI 0.602-0.8) for the prediction of DCI and clinical vasospasm, respectively. CONCLUSIONS The Practical Risk Chart adequately predicts the risk of DCI following aSAH. However, the best-fit model represents a simpler stratification scheme, using only the Hunt and Hess grade and the modified Fisher scale, and produces a comparable AUC.
authors.affiliation: Department of Neurosurgery, University of Alabama at Birmingham.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Foreman
authors.affiliation: Harvard Medical School; and.
authors.forename: Michelle H
authors.initials: MH
authors.lastname: Chua
authors.affiliation: Department of Neurosurgery, University of Alabama at Birmingham.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Harrigan
authors.affiliation: Department of Neurosurgery, University of Alabama at Birmingham.
authors.forename: Winfield S
authors.initials: WS
authors.lastname: Fisher
authors.affiliation: Pediatric Neurosurgery, Children's of Alabama, Birmingham, Alabama.
authors.forename: R Shane
authors.initials: RS
authors.lastname: Tubbs
authors.affiliation: Pediatric Neurosurgery, Children's of Alabama, Birmingham, Alabama.
authors.forename: Mohammadali M
authors.initials: MM
authors.lastname: Shoja
authors.affiliation: Department of Neurosurgery, University of Alabama at Birmingham.|Division of Neurosurgery, Beth Israel Deaconess Medical Center, Harvard University, Boston, Massachusetts.
authors.forename: Christoph J
authors.initials: CJ
authors.lastname: Griessenauer
mesh_terms: D002545:Brain Ischemia; D002544:Cerebral Infarction; D015331:Cohort Studies; D006801:Humans; D011446:Prospective Studies; D013345:Subarachnoid Hemorrhage
keywords: AUC = area under the receiver operating characteristic curve; CARAS = Cerebral Aneurysm Renin Angiotensin System; CTA = CT angiography; DCI = delayed cerebral ischemia; DSA = digital subtraction angiography; ICU = intensive care unit; Practical Risk Chart; SAH = subarachnoid hemorrhage; WFNS = World Federation of Neurosurgical Societies; aSAH = aneurysmal SAH; aneurysm; delayed cerebral ischemia; ischemia; prediction; subarachnoid hemorrhage; vascular disorders; vasospasm