Key result
Hyponatremia after aneurysmal subarachnoid hemorrhage increased the risk of vasospasm (OR 2.93; 95% CI 1.77-4.84) but was not associated with poor outcome (OR 1.15; 95% CI 0.44-3.02).
Why the study?
Hyponatremia after aneurysmal subarachnoid hemorrhage is common, but its incidence and association with vasospasm, morbidity, and mortality had yet to be defined.
Is hyponatremia associated with vasospasm, prolonged hospital stay, and poor outcomes in patients with aneurysmal subarachnoid hemorrhage?
Meta-Analysis (n=10,512)
Is hyponatremia associated with vasospasm, prolonged hospital stay, and poor outcomes in patients with aneurysmal subarachnoid hemorrhage?
Odds Ratio: 2.93 (95% CI 1.77–4.84)
Hyponatremia is common after aneurysmal subarachnoid hemorrhage and is associated with an increased risk of vasospasm and longer hospital stays, but not with overall poor clinical outcomes.
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.
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Gillespie et al. (2025) conducted a meta-analysis in aneurysmal subarachnoid hemorrhage (aSAH) (n=10,512). Hyponatremia vs. Normonatremia was evaluated on Vasospasm (OR 2.93, 95% CI 1.77-4.84). Hyponatremia after aneurysmal subarachnoid hemorrhage increased the risk of vasospasm (OR 2.93; 95% CI 1.77-4.84) but was not associated with poor outcome (OR 1.15; 95% CI 0.44-3.02).
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