Editors' note: Association between aspirin dose and subarachnoid hemorrhage from saccular aneurysms: A case-control study

Abstract

In their retrospective case–control study of nearly 5,000 patients with saccular aneurysms, Can et al. found a protective effect of aspirin use with regard to aneurysm rupture. Furthermore, there appeared to be a dose–response relationship, which added to the biologic plausibility of their findings. The investigators postulated that the anti-inflammatory effect of aspirin may attenuate rupture risk in these patients. Vilanilam et al. mention that the data of Can et al. corroborate at least 2 prior investigations. Dr. Juvela, of the University of Helsinki, contends that the protective effect in this study may be confounded by selection bias—in which sicker, older patients were more likely to have taken aspirin prior to aneurysm identification or be on antihypertensive medications. At the request of Dr. Juvela, Can et al. also evaluate statin use and prior stroke as potential confounders, and find no significant association with aneurysm rupture. While aspirin may attenuate the risk of the index rupture event, the investigators found that aspirin use was associated with a significant, 8-fold higher odds of rerupture prior to definitive aneurysm treatment, although event rates were small. Vilanilam et al. question the relationship between aspirin dose and risk of rerupture; however, only 4 of 17 patients who reruptured were on aspirin prior to the index event, limiting a formal dose–response assessment. In their retrospective case–control study of nearly 5,000 patients with saccular aneurysms, Can et al. found a protective effect of aspirin use with regard to aneurysm rupture. Furthermore, there appeared to be a dose–response relationship, which added to the biologic plausibility of their findings. The investigators postulated that the anti-inflammatory effect of aspirin may attenuate rupture risk in these patients. Vilanilam et al. mention that the data of Can et al. corroborate at least 2 prior investigations. Dr. Juvela, of the University of Helsinki, contends that the protective effect in this study may be confounded by selection bias—in which sicker, older patients were more likely to have taken aspirin prior to aneurysm identification or be on antihypertensive medications. At the request of Dr. Juvela, Can et al. also evaluate statin use and prior stroke as potential confounders, and find no significant association with aneurysm rupture. While aspirin may attenuate the risk of the index rupture event, the investigators found that aspirin use was associated with a significant, 8-fold higher odds of rerupture prior to definitive aneurysm treatment, although event rates were small. Vilanilam et al. question the relationship between aspirin dose and risk of rerupture; however, only 4 of 17 patients who reruptured were on aspirin prior to the index event, limiting a formal dose–response assessment.