Rebleeding drives poor outcome in aneurysmal subarachnoid hemorrhage independent of delayed cerebral ischemia: a propensity-score matched cohort study

OBJECTIVE Delayed cerebral ischemia (DCI) and aneurysm rebleeding contribute to morbidity and mortality in aneurysmal subarachnoid hemorrhage (aSAH); however, the relationship between their impacts on overall functional outcome is incompletely understood. METHODS The authors conducted a cohort study of all aSAH during the study period from 2001 to 2016. Primary end points were overall functional outcome and ischemic aSAH sequelae, defined as delayed cerebral ischemia (DCI), DCI with infarction, symptomatic vasospasm (SV), and global cerebral edema (GCE). Outcomes were compared between the rebleed and nonrebleed cohorts overall and after propensity- score matching (PSM) for risk factors and treatment modality. Univariate and multivariate ordered logistic regression analyses for functional outcomes were performed in the PSM cohort to identify predictors of poor outcome. RESULTS Four hundred fifty-five aSAH cases admitted within 24 hours of aneurysm rupture were included, of which 411 (90%) experienced initial aneurysm ruptures only, while 44 (10%) had clinically confirmed rebleeding. In the overall cohort, rebleeding was associated with significantly worse functional outcome, longer intensive care unit length of stay (LOS), and GCE (all p < 0.01); treatment modality, overall LOS, DCI, DCI with infarction, and SV were nonsignificant. In the PSM analysis of 43 matched rebleed and 43 matched nonrebleed cases, only poor functional outcome and GCE remained significantly associated with rebleeding (p < 0.01 and p = 0.02, respectively). Multivariate regression identified that both rebleeding (HR 21.5, p < 0.01) and DCI (HR 10.1, p = 0.01) independently predicted poor functional outcome. CONCLUSIONS Rebleeding and DCI after aSAH are highly morbid and potentially deadly events after aSAH, which appear to have independent negative impacts on overall functional outcome. Early rebleeding did not significantly affect the risk of delayed ischemic complications.