Association between serum vitamin D levels and functional outcomes in ischemic stroke patients: A systematic review and meta-analysis

ObjectiveTo evaluate the correlation between serum vitamin D levels and neurological function prognosis, including the overall cognitive level, in patients with ischemic stroke in a meta-analysis using Pearson or Spearman correlation coefficients.MethodsPubMed, Cochrane Library, Web of Science, and Embase databases were searched for relevant studies published from inception to June 2025. Stata version 16.0. was used to conduct the meta-analysis.ResultsA total of fifteen studies involving 2030 participants aged 18-94 years were included. The meta-analysis demonstrated a significant inverse association between serum vitamin D levels and stroke severity and outcomes, as reflected by the admission Modified Rankin Scale score, admission National Institutes of Health Stroke Scale score, and Modified Rankin Scale score at 3 months (combined Fisher's Z/r: -0.37/-0.35, 95% confidence interval: -0.68 to -0.06; -0.46/-0.43, 95% confidence interval: -0.55 to -0.37; and -0.21/-0.21, 95% confidence interval: -0.38 to -0.05, respectively). Higher serum vitamin D levels may be positively correlated with post-stroke cognitive improvement (combined Fisher's Z = 0.34, 95% confidence interval: 0.24 to 0.45).ConclusionSerum vitamin D levels in patients with ischemic stroke were significantly negatively correlated with neurological function prognosis and, possibly, better cognitive outcomes.