BACKGROUND: Despite its high prevalence, known association with vascular disease and stroke incidence and fatality, little is known about the contribution of vitamin D status to a worse outcome after ischemic stroke. Therefore, we sought to assess whether low serum 25-hydroxyvitamin D (25[OH]D), a marker of vitamin D status, is predictive of the ischemic infarct volume and whether it relates to a worse outcome.

METHODS: We retrospectively analyzed prospective, consecutive acute ischemic stroke patients evaluated from January 2013 to January 2014 at a tertiary referral center. All patients (n = 96) had a magnetic resonance imaging-proven acute ischemic stroke. Multivariable linear and logistic regression analyses were used to test whether vitamin D represents an independent predictor of infarct volume and poor 90-day outcome (modified Rankin Scale score of > 2).

RESULTS: In univariable analyses, lacunar infarct etiology, lower admission National Institutes of Health Stroke Scale, and higher serum 25(OH)D concentration were associated with smaller infarct volumes (P < .05). The association of 25(OH)D with ischemic infarct volume was independent of other known predictors of the infarct extent (P = .001). Multivariable analyses showed that the risk for a poor 90-day outcome doubled with each 10-ng/mL decrease in serum 25(OH)D.

CONCLUSIONS: Low serum 25(OH)D was independently associated with larger ischemic infarct volume, which may partially explain observed worse outcomes in ischemic stroke patients with poor vitamin D status. Although causality remains to be proven, our results provide the rationale to further explore vitamin D as a promising marker for cerebral ischemic vulnerability and to identify stroke patients at high risk for poor outcome.