A scoping review of national subarachnoid haemorrhage registries

BACKGROUND: Aneurysmal subarachnoid haemorrhage (aSAH) is a major cause of premature death and disability. Although evidence-based guidelines exist, implementation is inconsistent and variation in care persists. Ischaemic stroke registries have improved guideline-concordant care, and several reviews have described their variables, coverage, governance and resource requirements. However, there has been no previous review of national aSAH registries. AIMS: To systematically identify and describe aSAH registries with respect to governance, case identification, data collection and general characteristics. METHODS: We searched MEDLINE (Ovid) for English-language studies published from inception to 1st April 2026. Eligible registries included unselected national cohorts of aSAH patients with ≥1 year of prospective data collection. Two reviewers independently screened titles, abstracts and full-texts. Data were extracted from peer-reviewed publications, registry websites or reports. RESULTS: Eleven registries were identified, established between 1994-2009. Only one was a dedicated aSAH registry and, of the screened stroke registries, ten included aSAH patients. Four mandated hospital participation, and 81.8% employed no-consent or opt-out models. Governance, case identification and data collection varied substantially, with limited standardisation of consent and data entry. While most captured core inpatient variables, only 36.4% included sufficient detail to derive aSAH severity scores or aneurysm characteristics. Most registries were government led, with variable coverage, quality control and feedback mechanisms, typically focused on ischaemic stroke rather than aSAH-specific indicators. CONCLUSION: Few stroke registries include aSAH patients, and most are not optimised to capture disease-specific variables. International harmonisation of core aSAH data variables and development of dedicated or nested registry modules is likely to improve global aSAH care.