Why She? A Retrospective Study on Sex Inequality Related to Subarachnoid Haemorrhage

Abstract

Subarachnoid haemorrhage (SAH) is the only type of stroke with female predominance. We conducted a retrospective analysis of SAH patients throughout a decade and tried to establish any reason for such remarkable sex difference. We conducted a retrospective analysis of subarachnoid haemorrhages treated in Istria County between 2010 and 2021. Some of those patients were referred to a comprehensive stroke centre and we collected those data too. We also collected data regarding the outcome recorded at follow up exams of patients treated for SAH in that period. A total of 193 patients with subarachnoid haemorrhage were found in observed period. We found a lower incidence regarding general population but with a tendency to increase, compared with data from other studies. Among all SAH, 113 were female, which makes a Risk Ratio (RR) of 1.44. The highest RR in females was in aneurysmal subarachnoid haemorrhages, 2.06. We obtained a similar high RR of 2.03 in the case of female ruptured multiple intracranial aneurysms (IA), clearly with a worse outcome. Conversely, the RR in non-aneurysmal subarachnoid haemorrhages and perimesencephalic subarachnoid haemorrhages was lower in the case of female sex and amounted 0.67. We noticed similar sex inequality as shown in other studies, so we can also state that women are at higher risk of IA rupture than men. The reason has to be multifactorial. As found in this study, women have different predilection sites of IA rupture compared with men so we strongly believe that certain hemodynamic forces may lead to aneurysm growth and rupture. As we also confirmed IA rupture is age dependent more in women than in men. As shown in other studies, oestrogen level might be the reason for that. Future studies should further establish and prove these risk factors for IA aneurysm rupture and improve preventive measures.