Prevalence and correlates of vitamin D deficiency in adults after traumatic brain injury

Objectives: Traumatic brain injury (TBI) is a major cause of long-term disability with variable recovery. Preclinical studies suggest that vitamin D status influences recovery after TBI. However, there is no published clinical data on links between vitamin D status and TBI outcomes. To determine the: (i) prevalence of vitamin D deficiency/insufficiency, and associations of vitamin D status with (ii) demographic factors and TBI severity, and with (iii) cognitive function, symptoms and quality of life, in adults after TBI. Design: Retrospective audit of patients seen between July 2009 and March 2015. Serum vitamin D (25- hydroxy-cholecalciferol) was categorised as deficient (70nmol/L). Patients: 353 adults seen in tertiary hospital clinic (75.4% lighter-skinned, 74.8% male, age median 35.1y, range 26.6-48.3y), 0.3-56.5 months after TBI (74.5% moderate-severe). Measurements: Serum vitamin D concentrations; Addenbrooke’s Cognitive Examination (ACE-R), Beck Depression Inventory II (BDI-II), SF-36 Quality of Life, Pittsburgh Sleep Quality Index. Results: 46.5% of patients after TBI had vitamin D deficiency and 80.2% insufficiency/deficiency. Patients with vitamin D deficiency had lower ACE-R scores than those vitamin D replete (mean effect size ± SEM 4.5 ± 2.1, P=0.034), and higher BDI-II scores than those vitamin D insufficient (4.5 ± 1.6, P=0.003), correcting for age, gender, time since TBI, TBI severity. There was no association between vitamin D status and markers of TBI severity, sleep or quality of life. Conclusion: Vitamin D deficiency is common in patients after TBI and associated with impaired cognitive function and more severe depressive symptoms