Vitamin D deficiency is associated with worse neurological outcomes in moderate and severe traumatic brain injury: A prospective observational cohort study.

Vitamin D deficiency is correlated with neuroinflammation and neurocognitive defects. The present study investigated the relationship between the serum level of vitamin D and intensive care unit (ICU) length of stay, nosocomial infection, Acute Physiology and Chronic Health Evaluation II (APACHE II) score during hospitalization, and Glasgow Outcome Scale-Extended (GOSE) at 3 months in patients with moderate and severe traumatic brain injury (TBI). This prospective observational cohort study included 300 moderate-severe TBI patients admitted between May 2021 and May 2022. Demographic information and clinical characteristics of patients were collected prospectively. Serum vitamin D level (25-hydroxyvitamin D) was measured on admission and repeated 7 days after admission, as well as at the 3-month follow-up visit after admission. Vitamin D status was dichotomized into deficient (<20 ng/mL) and sufficient (≥20 ng/mL) groups. During a 90-day clinical follow-up, the GOSE, Glasgow Coma Scale, and mortality were assessed. The primary outcome was GOSE at 3 months after admission, and secondary outcomes were ICU length of stay, nosocomial infection, and APACHE II scores. Three hundred patients with a mean age of 34.98 ± 14.75 years were included. There were 222 (74%) patients with moderate TBI and 78 (26%) with severe TBI. In patients with moderate TBI, the 3-month Glasgow Coma Scale score significantly differed between vitamin D groups (P < .001). There was no difference in 3-month mortality between the groups. Baseline vitamin D measurements were not associated with ICU length of stay (P = .828), nosocomial infection (P = .077), and APACHE II score (P = .219). Vitamin D deficiency (<20 ng/mL) throughout the measurements was associated with lower GOSE scores (proportional odds ratio = 0.62, confidence interval: 0.40-0.93, P = .022). The results of this study suggest that vitamin D deficiency is associated with poorer neurological outcomes, as assessed by the GOSE, at 3 months. The potential role of vitamin D status as a prognostic marker and the effect of its supplementation in TBI patients should be investigated in future large-scale randomized controlled studies.