Hyponatremia Incidence After Subarachnoid Hemorrhage and Association with Outcomes: Systematic Review and Meta-Analysis.

Elena Roman, Samir Matloob, Lawrence Best, Carly Grandidge, Jonathan P Funnell, Ali M Alam, William H Cook, Musa China, Justyna O Ekert, Mohammad Ashraf, Youssef Chedid, Munashe Veremu, Jasneet Dhaliwal, Anca Mihaela-Vasilica, Conor S Gillespie, Alex E Henney, Lana Al-Nusair, Keng Siang Lee

Journal: World neurosurgery 2025;195():123616

PMID: 39732459

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Abstract

OBJECTIVE

Hyponatremia after aneurysmal subarachnoid hemorrhage (aSAH) is common; however, the incidence, and association with vasospasm, morbidity, and mortality, has yet to be defined. We aimed to identify incidence of hyponatremia after aSAH, and quantify its association with measurable outcomes.

METHODS

A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review and meta-analysis was conducted (international prospective register of systematic reviews ID CRD42022363472). Articles published in MEDLINE, Embase, and Cochrane Library between January 1990 and January 2024 were included. Hyponatremia definitions, incidence during admission, and association among vasospasm, length of hospital stay, and poor outcome (Glasgow Outcome Scale 3 or less) were identified. Pooled incidence rates and binary and continuous outcomes were calculated using random effects meta-analysis models.

RESULTS

In total, 52 studies (10,512 patients) were included. Most studies included patients admitted to tertiary neuroscience centers (61.5%, N = 32), or critical care units (23.1%, N = 11). Sodium of less than 135 mmol/L was the most commonly used hyponatremia definition (84.6%, N = 44). The pooled incidence of hyponatremia was 37.0% (95% confidence interval [CI]: 31.7%-42.4%). Hyponatremia increased the risk of vasospasm (15 studies; odds ratio: 2.93; 95% CI: 1.77-4.84), and length of hospital stay (3 studies, 16.4 days vs. 8.0 days, mean difference 8.5 [95% CI: 4.6-12.4]), but was not associated with poor outcome (10 studies; odds ratio 1.15; 95% CI 0.44-3.02). These findings remained when carrying out sensitivity analysis for different hyponatremia and outcome definitions, bias, and aSAH populations.

CONCLUSIONS

Hyponatremia is common in aSAH, may increase the likelihood of vasospasm, but in isolation does not appear to affect overall outcomes. Managing hyponatremia effectively should be a priority for treating clinicians.

Address: Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Department of Neurosurgery, Addenbrooke's Hospital, Cambridge, UK.; Department of Neuroscience, University College London Medical School, London, UK.; Department of Basic and Clinical Neurosciences, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.; Department of Cardiovascular and Metabolic Medicine, University of Liverpool, Liverpool, UK; Metabolism and Nutrition Research Group, Liverpool University Hospitals NHS Foundation Trust, Liverpool, Merseyside, UK.; Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK.; Wolfson School of Medicine, University of Glasgow, Scotland, UK.; Department of Neurosurgery, The Royal London Hospital, London, UK.; Department of Neurosurgery, Oxford University Hospitals NHS Foundation Trust, Oxford, Oxfordshire, UK.; Department of Neuroscience, University College London Medical School, London, UK; Department of Neurosurgery, Oxford University Hospitals NHS Foundation Trust, Oxford, Oxfordshire, UK. Electronic address: [email protected].

DOI: 10.1016/j.wneu.2024.123616

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MeSH Terms: Humans, Hyponatremia, Subarachnoid Hemorrhage, Incidence, Vasospasm, Intracranial, Length of Stay