Vitamin D Deficiency Is Associated with Increased Mortality and Seizure Risk After Nontraumatic Subarachnoid Hemorrhage: A Propensity Score-Matched Cohort Study

Background: Subarachnoid hemorrhage (SAH) is associated with high morbidity and mortality despite advances in neurocritical care. Vitamin D plays a role in immune modulation, endothelial function, and neuroprotection; however, its impact on outcomes following SAH remains poorly defined. We evaluated the association between low vitamin D status and clinical outcomes in patients with nontraumatic SAH. Methods: We conducted a retrospective propensity score-matched cohort study using the TriNetX Research Network database. Adult patients with nontraumatic SAH and at least one recorded serum 25-hydroxyvitamin D level obtained within 3 months on or before diagnosis were included. The low vitamin D cohort was defined as 0–20 ng/mL, and the comparator cohort as 20–40 ng/mL. Cohorts were matched 1:1 using propensity scores adjusted for demographic and clinical covariates, including chronic kidney disease, liver disease, osteoporosis, and intestinal malabsorption. The primary outcome was 30-day all-cause mortality. Secondary outcomes included seizures, hydrocephalus, cerebral edema, and external ventricular drain placement. Results: After matching, 2314 patients were included in each cohort. Thirty-day mortality occurred in 9.3% of patients in the low vitamin D cohort and 7.6% of patients in the comparator cohort (hazard ratio [HR] 1.229; 95% CI, 1.006–1.503; p = 0.043). Seizures were more frequent in the low vitamin D cohort (8.6% vs. 6.9%; odds ratio [OR] 1.274; 95% CI, 1.026–1.581; p = 0.028). Hydrocephalus was also more common among patients with low vitamin D (5.1% vs. 3.9%; OR 1.328; 95% CI, 1.003–1.758; p = 0.047). No significant differences were observed in cerebral edema or external ventricular drain placement. Conclusions: Low vitamin D status was associated with increased short-term mortality, seizure incidence, and hydrocephalus following nontraumatic SAH. These findings suggest that vitamin D status may represent a potential prognostic biomarker warranting prospective investigation.