Associations between C-reactive protein and white blood cell count, occurrence of delayed cerebral ischemia and poor outcome following aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

This review and meta-analysis investigated associations of systemic inflammatory marker C-reactive protein (CRP) and white blood cell count (WBC) with occurrence of delayed cerebral ischemia (DCI) and poor functional outcome after aneurysmal subarachnoid hemorrhage (aSAH). Pubmed, EMBASE, and CENTRAL databases were searched until November 30, 2019, selecting prospective and retrospective studies of patients with spontaneous SAH due to ruptured aneurysm. Outcome measures were occurrence of DCI, defined as new focal neurological deficit or a deterioration of consciousness; and/or a new infarct on computed tomography or magnetic resonance imaging that was not visible initially. Occurrence of poor functional outcome at follow-up were measured by modified Rankin Scale or Glasgow outcomes scale. Fifteen studies analyzing data of 3268 patients with aSAH were included. Meta-analysis revealed early increase in CRP was significantly associated with higher risk of occurrence of DCI (pooled OR 1.30, 95% CI 1.10–1.54; P = 0.002), whereas not with poor functional outcome (pooled OR 1.02, 95% CI 1.00–1.04, P = 0.052). No significant associations between early increase in WBC and DCI (pooled OR 1.13, 95% CI 0.95–1.34; P = 0.179) were observed, whereas increase in WBC was significantly associated with increased risk of poor functional outcome (pooled OR 1.17, 95% CI 1.07–1.28, P = 0.001). Early increase in blood CRP appears to correlate with DCI after SAH, while increase in WBC correlates with poor functional outcome. However, strong conclusion cannot be made due to the small study number, between-study heterogeneity and suspicion of uncontrolled factors. Whether early phase CRP and WBC may serve as prognostic markers for aSAH needs more investigation.