Relationship between aspirin use and subarachnoid hemorrhage: A systematic Review and meta-analysis

The association between acetylsalicylic acid and subarachnoid haemorrhage: the Framingham Heart Study

Studies investigating the association between acetylsalicylic acid (ASA) use and spontaneous subarachnoid haemorrhage (SAH) in the general population have produced conflicting results. The aim of this study is to clarify the relationship between SAH and ASA. We included all participants who reported on ASA use during interim examinations of the Framingham Heart Study Cohorts. Using Cox proportional-hazards regression modelling, we estimated the hazard ratio (HR) associated with ASA use. 7692 participants were included in this study. There were 30 cases of SAH during follow up, with an estimated incidence of 10.0 per 100,000 person- years (CI 6.90-14.15). Univariate analysis showed no association between regular ASA use and SAH (HR, 0.33 [0.08-1.41]; p = 0.14). This was similar when accounting for smoking (HR, 0.35 [0.08-1.51]; p = 0.16). Using a large longitudinal dataset from the Framingham Heart Study, we observed some evidence suggesting fewer SAH in those participants taking regular ASA. However, multivariate statistical analysis showed no significant association between ASA use and SAH. Due to the low incidence of SAH in the general population, the absolute number of SAH events was low and it remains uncertain if a significant effect would become apparent with more follow up.

Aspirin and growth, rupture of unruptured intracranial aneurysms: A systematic review and meta-analysis

OBJECTIVES

Aspirin has been suggested as a potential therapeutic strategy to prevent the growth and rupture of unruptured intracranial aneurysms (UIAs), but there is still controversy. The aim of this systematic review and meta-analysis is to determine the association between aspirin use and growth, rupture of UIAs.

METHODS

We performed a systematic literature search of electronic databases to identify cohort and case-control studies investigating the relationship between aspirin use and growth or rupture of UIAs. Pooled odds ratio (OR) with corresponding 95% confidence interval (CI) were calculated using a random effects model. Heterogeneity among studies was quantified using the I² statistic, and potential publication bias was assessed using funnel plots. Sensitivity analysis was performed to verify the robustness of the intention-to-treat results. Subgroup analysis was conducted according to the frequency of aspirin use.

RESULTS

We identified 8 studies comprising 10,518 participants. The risk of bias was low to moderate. The pooled estimate showed that aspirin use was associated with a lower likelihood of growth of UIAs (OR = 0.25, 95% CI = 0.11-0.55; p = 0.0005) without statistical heterogeneity (p for Cochran Q statistic = 0.62, I² = 0%). Likewise, aspirin intake also significant decreased 58% risk of intracranial aneurysms rupture (OR = 0.42, 95% CI = 0.29-0.60; p < 0.00001) with moderate heterogeneity (p for Cochran Q statistic = 0.005, I² = 66%). Similar results were observed in the sensitivity analysis. Pooled OR of aspirin frequency subgroup analysis for less than or equal to 2 times per week was 0.82 (95%CI = 0.40-1.72; I² = 0%), for at least 3 times per week to daily was 0.25 (95%CI = 0.12-053; I² = 0%), for daily was 0.59 (95%CI: 0.47-0.74; I² = 0%), and for unknown was 0.26 (95%CI: 0.15-0.45; I² = 51%).

CONCLUSIONS

The results of this systematic review and meta-analysis indicates a beneficial effect of aspirin on growth and rupture of UIAs.

A meta-analysis of aspirin and subarachnoid hemorrhage in patients with intracranial aneurysms yields different results to the general population

BACKGROUND

Some studies have shown a protective association between aspirin use and subarachnoid hemorrhage. Other studies have found no relationship or the reverse. These studies differ in their study populations and definitions of subarachnoid hemorrhage.

AIMS

Our aim was to establish (1) if there is an association between aspirin and subarachnoid hemorrhage, (2) how this differs between the general population and those with intracranial aneurysms.

SUMMARY OF REVIEW

Studies reporting aspirin use and the occurrence of subarachnoid hemorrhage were included and grouped based on population (general population vs. aneurysm population). Odds ratios, hazard ratios, and confidence intervals were combined in random-effects models. Eleven studies were included. Overall, there was an association between aspirin and subarachnoid hemorrhage (OR 0.68 [0.48, 0.96]). However, populations were diverse and heterogeneity between studies high (p < 0.00001), questioning the validity of combining these studies and justifying analysis by population. In the general population, there was no difference in aspirin use between individuals with and without subarachnoid hemorrhage (OR 1.15 [0.96, 1.38]). In patients with intracranial aneurysms, aspirin use was greater in patients without subarachnoid hemorrhage (OR 0.37 [0.24, 0.58]), although these studies were at higher risk of bias.

CONCLUSIONS

There is an association between aspirin use and subarachnoid hemorrhage in patients with intracranial aneurysms. This apparent protective relationship is not seen in the general population. Prospective randomized studies are required to further investigate the effect of aspirin on unruptured intracranial aneurysms.