Association of aspirin use with risk of intracerebral hemorrhage in patients without history of stroke or transient ischemic attack in the UK Biobank.

Background: The association between aspirin use and the risk of intracerebral hemorrhage (ICH) among individuals without previous stroke events is inconclusive.

Aim: We investigated the association between regular aspirin use and ICH risk in middle-aged and older adults without previous stroke or transient ischemic attack (TIA).

Methods: This prospective population-based study included participants older than 40 years with no history of stroke or TIA from the UK Biobank. The main exposure was regular aspirin use. Cox regression analyses and propensity score matching analyses estimated the hazard ratios (HRs) for aspirin use for incident fatal and non-fatal ICH. We conducted pre-specified subgroup analyses for selecting individuals at high risk of ICH when using aspirin. Multiple sensitivity analyses were performed to test the robustness of our results.

Results: A total of 449,325 participants were included into final analyses (median (IQR) age 58 (50-63) years, 54.6% females), of whom 58,045 reported aspirin use. During a median follow-up of 12.75 (IQR: 12.03-13.47) years, 1557 (0.3%) incident ICH cases were identified, of which 399 (25.6%) were fatal. Aspirin was not associated with increased risk of overall (hazard ratio (HR): 1.11, 95% confidence interval (CI): 0.95-1.27, P = 0.188), fatal (HR: 1.03, 95% CI: 0.78-1.36, P = 0.846) and non-fatal (HR: 1.12, 95% CI: 0.95-1.33, P = 0.186) ICH. Propensity score matching analysis showed similar results. Subgroup analysis indicated that aspirin use in individuals older than 65 years or with concurrent anticoagulant use was correlated with increased risk of ICH.

Conclusion: In this large cohort study of middle-aged and older adults without stroke or TIA events, there was no significant association between aspirin use and ICH risk in the real-world setting. However, it is possible that aspirin use in those aged over 65 years and concurrent anticoagulant treatment may increase the risk of ICH.