Risk factors for aneurysmal subarachnoid hemorrhage in women: Systematic review and meta-analysis.

Background: Aneurysmal subarachnoid hemorrhage (aSAH) affects women more than men, unlike other stroke types. We completed a systematic review and meta-analysis of risk factors associated with the occurrence of aSAH in women. Method(s): A systematic search was conducted using the Pubmed, Scopus, Embase, and Medline databases from inception to November 2017 to identify studies that included aSAH risk factors among women only or mentioned female sex as a risk factor. The risk factors were assessed using meta-analysis if reported by at least two studies. Result(s): Fourteen studies (10 case-control; 4 cohort) were included. Female sex was associated with higher odds or risk of aSAH in pooled estimates of cohort studies (HRadjusted 1.90, 95% CI 1.47-2.46) but not in case-control studies (ORadjusted 1.44, 95% CI 0.83-2.52). Menarche at an early age (age <12 years HRcrude 1.15 [95% CI 0.52-2.55], age <13 years ORadjusted 3.24 [95% CI 1.25-4.03]), pregnancy at >=26 years (ORadjusted 1.78 [95% CI 1.13-2.80]), use of contraceptive pills (RRcrude range, 5.3-6.5), nulligravidity (ORadjusted 4.23 [95% CI 1.05-7.56]), aSAH predilection area (RRcrude 1.81) and being divorced (RRcrude 1.89) increased the risk for aSAH in women. Parity moderately decreased the risk for aSAH (parity >3 HRcrude 1.21 [95% CI 0.68-2.14], parity=2 ORadjusted 0.87 [95% CI 0.64-1.19], parity >=5, ORadjusted 0.25 [95% CI 0.03-1.89]). Conclusion(s): A number of risk factors, primarily related to reproductive hormones, for aSAH were identified in women. These could be potential causes of higher incidence of aSAH in women compared to men. There is a need for further research focused on aSAH in order to explore the association of these risk factors with aSAH in women.