title: Risk factors for re-bleeding of aneurysmal subarachnoid hemorrhage: meta-analysis of observational studies.
abstract: OBJECTIVE
  The mortality of re-bleeding following aneurysmal subarachnoid hemorrhage is high, and surviving patients often have poor clinical condition and worse outcome than patients with a single bleed. In this study, we performed an updated systematic review and meta-analysis to determine the most common risk factors for re-bleeding in this patient population, with the goal of providing neurologists, neurosurgeons, neuro-interventionalists with a simple and fast method to evaluate the re-bleeding risk for aneurysmal subarachnoid hemorrhage.
  
  
  METHODS
  We conducted a thorough meta-analysis of the risk factors associated with re-bleeding or re-rupture of intracranial aneurysms in cases published between 2000 and 2013. Pooled mean difference was calculated for the continuous variables (age), and pooled odds ratio (OR) was calculated for categorical factors. If heterogeneity was significant (p<0.05), a random effect model was applied; otherwise, a fixed model was used. Testing for pooled effects and statistical significance for each potential risk factor were analyzed using Review Manager software.
  
  
  RESULTS
  Our literature search identified 174 articles. Of these, only seven retrospective studies met the inclusion criteria. These seven studies consisted of 2470 patients, 283 of which had aneurysmal re-bleeding, resulting in a weighted average rate of re-bleeding of 11.3% with 95% confidence interval [CI]: 10.1-12.6. In this population, sex (OR 1.46; 95% CI: 1.11-1.92), high systolic blood pressure [SBP] (OR 2.52; 95% CI: 1.40-4.53), aneurysm size (OR 3.00; 95% CI: 2.06-4.37), clinical condition (Hunt & Hess) (OR 4.94; 95% CI: 2.29,10.68), and Fisher grade (OR 2.29; 95% CI: 1.45, 3.61) were statistically significant risk factors for re-bleeding.
  
  
  CONCLUSIONS
  Sex, high SBP, high Fisher grade, aneurysm size larger than 10mm, and poor clinical condition were independent risk factors for aneurysmal re-bleeding. The importance of early aneurysm intervention and careful consideration of patient risk factors should be emphasized to eliminate the risk of re-bleeding and poor outcome.
authors.affiliation: Sun Yat Sen Memorial Hospital, Neurosurgery Department, Sun Yat Sen Medical University, GuangZhou, People's Republic of China. Electronic address: gta_alfotih@yahoo.com.
authors.forename: Gobran Taha Ahmed
authors.initials: GT
authors.lastname: Alfotih
authors.affiliation: Sun Yat Sen Memorial Hospital, Neurosurgery Department, Sun Yat Sen Medical University, GuangZhou, People's Republic of China.
authors.forename: FangCheng
authors.initials: F
authors.lastname: Li
authors.affiliation: Sun Yat Sen Memorial Hospital, Neurosurgery Department, Sun Yat Sen Medical University, GuangZhou, People's Republic of China.
authors.forename: XinKe
authors.initials: X
authors.lastname: Xu
authors.affiliation: Sun Yat Sen Memorial Hospital, Neurosurgery Department, Sun Yat Sen Medical University, GuangZhou, People's Republic of China.
authors.forename: ShangYi
authors.initials: S
authors.lastname: Zhang
mesh_terms: D016208:Databases, Factual / Q000706:statistics & numerical data; D006801:Humans; D012008:Recurrence; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology* / Q000503:physiopathology*
keywords: Cerebral aneurysm; Meta-analysis; Re-bleeding risk factor; Subarachnoid hemorrhage