SynthesisNeurology2025
Risk Factors of Aneurysmal Subarachnoid Hemorrhage Including Analysis by Sex: A Systematic Review and Meta-Analysis.
Synthesis in Neurology, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers, 2 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
4 citing papers in PubMed, 2 syntheses or guidelines pooled it.
- Risk factors for saccular unruptured intracranial aneurysms: a systematic review and meta-analysis.European stroke journal · 2026Pooled it
- Underreporting of Sex-Specific Findings in Risk Factors for Unruptured Intracranial Aneurysms.Cerebrovascular diseases (Basel, Switzerland) · 2026Pooled it
- Recreational substance use and aneurysmal subarachnoid hemorrhage: differential effects of alcohol and THC.Neurosurgical review · 2026Article
- A Bedside Coagulation-Platelet Tipping Point for Mortality in Nontraumatic Subarachnoid Hemorrhage.Journal of multidisciplinary healthcare · 2026Article
Corrections and comments
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Authors and funding
9 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
BACKGROUND AND
objectivesA 2005 review identified smoking, hypertension, and excessive alcohol intake as the most important risk factors of aneurysmal subarachnoid hemorrhage (aSAH), but data on other factors remained inconclusive. While aSAH is more prevalent in female participants, evidence on sex differences and female-specific factors remains limited. Comprehensive identification of all risk factors, including potential sex differences and female-specific factors, is essential for improving prevention and accurately assessing aSAH risk. We aimed to determine whether there is now greater certainty around previously inconclusive risk factors, identify any new emerging factors, and explore sex differences in both established and emerging risk factors.
methodsWe conducted a systematic review and meta-analysis of cohort and case-control studies on prevalent lifestyle exposures, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. These exposures included smoking, hypertension, alcohol abuse, oral contraception, hormone replacement therapy, hypercholesterolemia, rigorous physical activity, lean body mass index, and diabetes. We calculated pooled sex-specific relative risks (RRs) and odds ratios (ORs) with 95% CIs for overall risk and female-to-male ratios of RRs (RRRs) and ORs (RORs) for sex comparisons.
resultsWe included 67 studies (34 cohort [8 with sex-specific data], 33 case-control [6 with sex-specific data]; n = 5,743,262; 57% female). A sex-specific association was found for current smoking (RRR 1.53, 95% CI 1.05-2.23), but not for hypertension (RRR 1.50, 95% CI 0.78-2.89) or excessive alcohol intake (RRR 0.46, 95% CI 0.13-1.63). Regular rigorous exercise (RR 0.74, 95% CI 0.53-1.04; OR 0.69, 95% CI 0.57-0.83) and diabetes (RR 0.75, 95% CI 0.55-1.02; OR 0.52, 95% CI 0.41-0.65) were associated with reduced risk, without sex-specific associations. Data on hypercholesterolemia (RR 1.24, 95% CI 0.97-1.58; OR 0.52, 95% CI 0.37-0.74) and lean BMI (RR 1.31, 95% CI 1.15-1.50; OR 1.39, 95% CI 0.74-2.60) were inconsistent and showed no sex-specific associations. Hormone replacement therapy (RR 1.03, 95% CI 0.72-1.48) and oral contraceptive use (RR 5.40, 95% CI 0.68-42.57) were limited to female patients, with current users compared with never users. Most studies contained potential sources of bias. DISCUSSION: Current smoking, but not hypertension or excessive alcohol, has a stronger association with aSAH in female patients than in male patients. Regular exercise and diabetes are associated with a reduced risk, with no sex-specific associations. Data on female-specific factors remain inconsistent. Targeted smoking prevention may particularly benefit female patients. Large-scale studies are needed to clarify the role of female-specific factors in explaining the higher incidence of aSAH in female patients.
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