Serum Vitamin D Status as a Predictor of Prognosis in Patients with Acute Ischemic Stroke

Abstract

Background: Low 25-hydroxyvitamin D (25(OH)D) concentrations have been shown to predict risk of cardiovascular disease and all-cause mortality. Although the prevalence of 25(OH)D deficiency is high in patients with acute stroke, the prognostic value of 25(OH)D in stroke has not been clearly established. The purpose of this study was to determine whether the baseline serum 25(OH)D level was associated with the functional outcome in patients with acute ischemic stroke. Methods: From June 2011 to January 2014, consecutive patients with acute ischemic stroke within 7 days of symptom onset were enrolled in this study from a prospectively maintained stroke registry. Serum 25(OH)D level was measured at admission. Clinical and laboratory data including stroke severity using the National Institute of Health Stroke Scale (NIHSS) score were collected during admission, and the functional outcome at 3 months was assessed by modified Rankin scale (mRS). The association between the baseline 25(OH)D level and a good functional outcome (mRS 0-2) at 3 months was analyzed by multiple logistic regression models. Results: A total of 818 patients were enrolled in this study. Mean age was 66.2 (±12.9) years, and 40.5% were female. The mean 25(OH)D level was 47.2 ± 31.7 nmol/l, and the majority of patients met vitamin D deficient status (<50 nmol/l; 68.8%), while an optimal vitamin D level (≥75 nmol/l) was present in only 13.6% of the patients, and 436 (53.3%) patients showed good functional outcome at 3 months. Serum 25(OH)D levels in patients with good outcomes were significantly higher than those with poor outcome (50.2 ± 32.7 vs. 43.9 ± 30.0 nmol/l, p = 0.007). The 3-month functional outcome was significantly associated with month-specific 25(OH)D quartiles in multivariable logistic regression analysis. After adjustment for age and sex, the highest 25(OH)D quartile group had higher tendency for good functional outcome at 3 months (odds ratio (OR) = 1.68, 95% confidence interval (CI) = 1.13-2.51). After fully adjusting for other potential confounders, such as stroke severity and vascular risk factors, the association was further strengthened with an OR (95% CI) of 1.90 (1.14-3.16). Other factors associated with good functional outcome in multivariable analysis were younger age, lower initial NIHSS score and absence of diabetes. Conclusions: This study suggests that serum 25(OH)D level is an independent predictor of functional outcome in patients with acute ischemic stroke. Further studies are required to determine whether vitamin D supplementation could improve functional outcome in patients with ischemic stroke.