Outcomes-based assessment of a new reference standard for delayed cerebral ischemia related to vasospasm in aneurysmal subarachnoid hemorrhage.

RATIONALE AND OBJECTIVES: The purpose is to perform outcomes-based assessment of a new reference standard for delayed cerebral ischemia (DCI) related to vasospasm.

MATERIALS AND METHODS: Retrospective study was performed with consecutive aneurysmal subarachnoid hemorrhage (A-SAH) patients between January 2002 and May 2009. A new reference standard for DCI was applied to the study population incorporating clinical and imaging criteria. Diagnostic accuracy was determined by chart diagnosis. Outcome measures for assessment included: permanent neurologic deficits, infarction, functional disability, treatment, and discharge status. Medical record review was performed by two blinded observers. Chi-square test calculated statistical significance between DCI and no DCI groups.

RESULTS: A total of 137 patients were included; 59% (81/137) classified as DCI and 41% (56/137) as no DCI by the reference standard. Overall accuracy is 96% (95% confidence interval 92-99) with 100% sensitivity, 92% specificity, 94% positive and 100% negative predictive values. Patients classified as DCI had 40% (32/81) permanent neurologic deficits and 57% (46/81) infarction compared to 0% (0/56) classified as no DCI. DCI patients had 33% (27/81) functional disability compared to 13% (7/56) classified as no DCI. Ninety-four percent (76/81) DCI patients received treatment compared to 0% (0/56) classified as no DCI. DCI group had 46% (37/81) discharged to rehabilitation facilities and 11% (9/81) mortality compared to 25% (14/56) and 2% (1/56), respectively, in no DCI group. There are statistically significant differences (P < .0001) between DCI and no DCI groups for all outcome measures.

CONCLUSION: This new reference standard has high diagnostic accuracy for DCI related to vasospasm. The outcomes-based assessment further supports its accuracy in correctly classifying A-SAH patients.