Reviewed by Virginia Thornley, M.D., Neurologist
This study asks if low dose aspirin in the 75-300 mg range causes an increase in the risk of intracranial hemorrhage. A national database in the UK was used which identified 199,079 new users of aspirin, each was matched to a patient with no aspirin use. Patients were taken from the 1st year of general practice. Those who had liver cirrhosis, cancer, esophageal varices were excluded. Ten thousand controls were sampled in the cohort. Cases were divided into intracranial hemorrhage, subdural hematoma, subarachnoid hemorrhage and fatal. Case control methods were used using a confidence interval of 95% with logistic regression. 1611 patients were found with intracranial bleed after following the patients for 5.4 years.
They found that in 400,000 patients followed for 14 years, low dose aspirin showed did not correlate with an increased risk of intracranial hemorrhage or subdural hematoma. Although most used 75mg, at a dose of 80-300mg it is unclear. Using low dose aspirin for at least 1 year showed a protective effect against subarachnoid hemorrhage. This study found that hemodialysis, renal dysfunction and warfarin use increases the risk of intracranial bleeding. Previous intracranial hemorrhage was associated with an 8-fold risk of a rebleed. Other risk factors increasing risk of intracranial bleed include previous ischemic stroke, smoking history, underweight, history of falls and dementia.
In summary, this is a large study concluding that intracranial hemorrhage is not related to low dose aspirin at 75 mg and is, in fact, protective against subarachnoid hemorrhage at greater than 1 year. Further studies, however, are needed for dosages at 80-300mg to determine a correlation.
- “Low-dose aspirin and the risk of intracranial bleed, an observational study in UK general practice,” Soriano, L.C., et.al, Neurology, 2017; 22: 2280-2287