Letter by Hasan et al Regarding Article, “Aspirin and Risk of Subarachnoid Hemorrhage: Systematic Review and Meta-Analysis”
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To the Editor:
In their meta-analysis of antiplatelet use and risk of aneurysmal subarachnoid hemorrhage (aSAH), Phan et al1 suggested that short-term (<3 months) use of aspirin (ASA) is associated with increased risk of aSAH, whereas there was no significant difference found in terms of risk of aSAH for 3 to 12 months, 1 to 3 years, and >3 years duration of use. Their findings are most consistent with 2 biases. First, patients are most likely to take ASA in the 3 months preceding aSAH for headaches that are a frequent precursor for aneurysmal enlargement, incipient rupture, or smaller leaks. Thus, ASA use in this setting is most likely a marker of an evolving aneurysm rather than a cause of rupture. If ASA was truly a causal risk factor for aSAH, one should see an increased risk for all time periods. Second, patients and family members are much more likely to recall recent medication use associated with a clinical event rather than medication use in the more distant past, unless medication use has …