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Published on: October 15, 2021
Low-dose aspirin and risk of intracranial bleeds: An observational study in UK general practice
Lucía Cea Soriano1, David Gaist2, Montse Soriano-Gabarró2
1From the Spanish Centre for Pharmacoepidemiologic Research (CEIFE) (L.C.S., L.A.G.R.), Madrid; Department of Preventive Medicine and Public Health (L.C.S.), Faculty of Medicine, Complutense University of Madrid, Spain; Department of Neurology (D.G.), Odense University Hospital; Department of Clinical Research (D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark; Epidemiology (M.S.-G.), Bayer AG, Berlin, Germany; EpiMed Communications Ltd (S.B.), Abingdon, Oxford; and London School of Hygiene and Tropical Medicine (S.B.), UK. luciaceife@gmail.com.
Insights
Low-dose aspirin use does not increase the risk of intracranial bleeds (ICBs). However, long-term use (≥1 year) is linked to a reduced risk of subarachnoid hemorrhage (SAH).
Area of Science:
- Cardiovascular Medicine
- Neurology
- Pharmacology
Background:
- Low-dose aspirin is widely used for primary and secondary prevention of cardiovascular events.
- The risk of intracranial bleeds (ICBs) is a significant concern with aspirin use, particularly in older populations.
- Understanding the specific risks associated with different types of ICBs is crucial for clinical decision-making.
Purpose of the Study:
- To quantify the association between new use of prophylactic low-dose aspirin and the risk of various types of ICBs.
- To investigate potential dose-response or duration-of-use relationships for ICB risk.
- To provide evidence-based guidance on aspirin's safety profile regarding intracranial hemorrhage.
Main Methods:
- A large, population-based cohort study utilizing UK primary care data.
- Inclusion of 199,079 new users of low-dose aspirin (75-300 mg) aged 40-84 years, matched 1:1 with non-users.
- Follow-up for up to 14 years to identify incident ICBs, with validation through record review or hospitalization data.
Main Results:
- No overall increased risk of any ICB (RR 0.98, 95% CI 0.84-1.13) was observed.
- Specific risks for intracerebral hemorrhage (ICH) and subdural hematoma (SDH) were not significantly increased.
- A decreased risk was noted for subarachnoid hemorrhage (SAH) (RR 0.77, 95% CI 0.58-1.01), particularly with use for ≥1 year (RR 0.69, 95% CI 0.50-0.94).
Conclusions:
- New use of low-dose aspirin is not associated with an elevated risk of intracranial bleeds.
- Long-term prophylactic use of low-dose aspirin (≥1 year) may be associated with a reduced risk of subarachnoid hemorrhage.
- These findings support the continued use of low-dose aspirin for appropriate indications while reassuring regarding ICB risk.
Objective:
To quantify the risk of intracranial bleeds (ICBs) associated with new use of prophylactic low-dose aspirin using a population-based primary care database in the United Kingdom.
Methods:
A cohort of new users of low-dose aspirin (75-300 mg; n = 199,079) aged 40-84 years and a 1:1 matched cohort of nonusers of low-dose aspirin at baseline were followed (maximum 14 years, median 5.4 years) to identify incident cases of ICB, with validation by manual review of patient records or linkage to hospitalization data. Using 10,000 frequency-matched controls, adjusted rate ratios (RRs) with 95% confidence intervals (CIs) were calculated for current low-dose aspirin use (0-7 days before the index date [ICB date for cases, random date for controls]); reference group was never used.
Results:
There were 1,611 cases of ICB (n = 743 for intracerebral hemorrhage [ICH], n = 483 for subdural hematoma [SDH], and n = 385 for subarachnoid hemorrhage [SAH]). RRs (95% CI) were 0.98 (0.84-1.13) for all ICB, 0.98 (0.80-1.20) for ICH, 1.23 (0.95-1.59) for SDH, and 0.77 (0.58-1.01) for SAH. No duration of use or dose-response association was apparent. RRs (95% CI) for ≥1 year of low-dose aspirin use were 0.90 (0.72-1.13) for ICH, 1.20 (0.91-1.57) for SDH, and 0.69 (0.50-0.94) for SAH.
Conclusion:
Low-dose aspirin is not associated with an increased risk of any type of ICB and is associated with a significantly decreased risk of SAH when used for ≥1 year.
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