Vitamin D Deficiency in Traumatic Brain Injury and Its Relationship with Severity of Injury and Quality of Life: A Prospective, Observational Study

This single-center prospective observational study aims to describe the prevalence of vitamin D deficiency (VDD) in the traumatic brain injury (TBI) population and identify any relationship between vitamin D and severity of head injury or quality of life. One hundred twenty-four TBI patients had serum vitamin D (25-OHD) levels measured at the local post-TBI endocrine screening clinic over 20 months. Quality of Life after Brain Injury questionnaires were completed by the patient concurrently. A multivariate regressional analysis was performed, controlling for age, season, ethnicity, time since injury, TBI severity, and gender. A total of 34% (n = 42) of the cohort were vitamin D deficient (25-OHD <25 nmol/L), with a further 23% (n = 29) having insufficient levels (25-OHD 25-50 nmol/L). Vitamin D was significantly lower in patients with severe TBI than in patients with mild TBI (n = 95; p = 0.03; confidence interval [CI] 95% -23.60 to -1.21; mean effect size 12.40 nmol/L). There was a trend for self-reported quality of life to be better in patients with optimum vitamin D levels than in patients with deficient vitamin D levels, controlling for severity of injury (n = 81; p = 0.05; CI 95% -0.07 to 21.27). This is the first study to identify a significant relationship between vitamin D levels and severity of head injury. Clinicians should actively screen for and treat VDD in head-injured patients to reduce the risk of further morbidity, such as osteomalacia and cardiovascular disease. Future research should establish the natural history of vitamin D levels following TBI to identify at which stage VDD develops and whether vitamin D replacement could have a beneficial effect on recovery and quality of life.