Aspirin and Subarachnoid Haemorrhage in the UK Biobank.

Previous studies investigating the relationship between aspirin use and subarachnoid haemorrhage (SAH) have yielded conflicting results. In this study, we aimed to clarify the association between aspirin and SAH in the general population. The UK Biobank is a prospective population-based cohort study. Sex, age, smoking, alcohol, medication use, hypertension, blood pressure, ischaemic heart disease and stroke were recorded at baseline assessments. Follow-up is conducted through linkages to National Health Service data including electronic, coded death certificate, hospital and primary care data. Cox proportional hazards modelling was used to analyse the association between aspirin use and SAH. Of the 501,060 participants included in the analysis, a total of 579 suffered from spontaneous SAH after their baseline assessment. There was no relationship between aspirin and SAH of all causes (HR, 1.16 [0.92-1.46]), aneurysmal SAH (HR, 1.15 [0.91-1.47]) or non-aneurysmal SAH (HR, 1.29 [0.54-3.09]). Aspirin use was associated with SAH resulting in death (HR, 1.69 [1.14-2.51]), especially out of hospital death (HR, 2.10 [1.13-3.91]). Despite reports of a protective association between aspirin and SAH in patients with known unruptured aneurysms, this study has not demonstrated the same effect in the general population. However, aspirin users were more likely to suffer SAH resulting in death, especially out of hospital.