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

Association of Global Ultraviolet Radiation With the Incidence of Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND OBJECTIVES

Inflammation is a key pathomechanism for growth and rupture of intracranial aneurysms. Anti-inflammatory mechanisms may reduce rupture of intracranial aneurysms and the incidence of aneurysmal subarachnoid hemorrhage (SAH). Ultraviolet (UV) radiation from sunlight exposure induces systemic anti-inflammatory responses through immunosuppressive mechanisms. We studied whether SAH incidence is associated with UV radiation.

METHODS

Global SAH incidence, time trends, and regional differences from 32 countries were linked to UV radiation data from the Tropospheric Emission Monitoring Internet Service. Odds between low vs high UV exposure and SAH incidence were calculated. Correlation analysis was performed using R (R 4.1.2).

RESULTS

SAH incidences ranged from 1.3 to 27 per 100 000 patient-years (p-y) and UV index from 1.76 to 11.27. The correlation coefficient (rho) between SAH incidence and UV index was -0.48 (P = .012). SAH incidence was highest in Japan (13.7-27.9 p-y) with an UV index 6.28. UV index was highest in Chile 11.27 with a lower SAH incidence (3.8-4.8 p-y). The lowest UV index 1.76 was seen in Iceland with higher SAH incidence (9.8 p-y).Within Europe, regions with higher UV indices reported lower SAH incidences (Northwest Europe: SAH incidence p-y 8.61/UV index 2.85; Southeast Europe: SAH incidence p-y 7.37/UV index 4.65) with a significant inverse correlation (rho = -0.68, P = .004) and not a significant correlation between non-European countries (rho = -0.43, P = .19). Low exposure of UV radiation in global regions predicted higher than median incidences of SAH with an odds ratio 5.13 (95% CIs 1.02-31.5).

CONCLUSION

The incidence of SAH is inversely associated with UV radiation. Further studies should assess the actual UV exposure in relation to SAH incidence and potential biological explanations for the relation we found.

The association between blood pressure at admission and in-hospital mortality in patients with subarachnoid hemorrhage

PURPOSE

The objective of this study was to examine the association between mean arterial pressure (MAP) at admission and in-hospital mortality among patients diagnosed with subarachnoid hemorrhage (SAH).

METHODS

In this cohort study, 1420 SAH patients were categorized into four groups based on quartiles of MAP: <82 mmHg group, 82-93 mmHg group, 93-103 mmHg group, and >103 mmHg group. Furthermore, the X-tile program was used to divide all patients into four groups: < 81.7 mmHg group, 81.7-92.3 mmHg group, 92.3-103.7 mmHg group, and > 103.7 mmHg group. The association between MAP and in-hospital mortality of SAH patients was evaluated using univariate and multivariable Cox proportional hazards models. A restricted cubic spline (RCS) was plotted to explore the association between MAP at admission and in-hospital mortality in patients with SAH.

RESULTS

The median follow-up duration was 7.87 days, during which, 1219 (85.85%) patients survived. After adjusting for confounding factors, MAP <82 mmHg (hazard ratio (HR)=1.67, 95% confidence interval (CI): 1.08-2.57) or MAP >103 mmHg (HR=2.13, 95% CI: 1.38-3.29) was associated with increased risk of in-hospital mortality of SAH patients. Subgroup analysis depicted that MAP <82 mmHg or MAP >103 mmHg was associated with increased risk of in-hospital mortality in male patients or those aged ≥ 65 years. MAP >103 mmHg was linked with elevated risk of in-hospital mortality in patients aged <65 years; individuals with normal and underweight, overweight, and obesity; or people with hypertension.

CONCLUSION

The findings may offer a preliminary estimate of the optimum range for SAH patients for future randomized trials.

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 Subarachnoid Haemorrhage in the UK Biobank

Previous studies investigating the relationship between aspirin use and subarachnoid haemorrhage (SAH) have yielded conflicting results. In this study, we aimed to clarify the association between aspirin and SAH in the general population. The UK Biobank is a prospective population-based cohort study. Sex, age, smoking, alcohol, medication use, hypertension, blood pressure, ischaemic heart disease and stroke were recorded at baseline assessments. Follow-up is conducted through linkages to National Health Service data including electronic, coded death certificate, hospital and primary care data. Cox proportional hazards modelling was used to analyse the association between aspirin use and SAH. Of the 501,060 participants included in the analysis, a total of 579 suffered from spontaneous SAH after their baseline assessment. There was no relationship between aspirin and SAH of all causes (HR, 1.16 [0.92-1.46]), aneurysmal SAH (HR, 1.15 [0.91-1.47]) or non-aneurysmal SAH (HR, 1.29 [0.54-3.09]). Aspirin use was associated with SAH resulting in death (HR, 1.69 [1.14-2.51]), especially out of hospital death (HR, 2.10 [1.13-3.91]). Despite reports of a protective association between aspirin and SAH in patients with known unruptured aneurysms, this study has not demonstrated the same effect in the general population. However, aspirin users were more likely to suffer SAH resulting in death, especially out of hospital.