Vitamin D deficiency is endemic in neurosurgical patients and is associated with a longer length of inpatient stay

Abstract

Introduction: Vitamin D deficiency is common in spinal surgery and critical care. Hypovitaminosis D may impact on outcomes in cranial neurosurgical care and play roles in underlying disease processes.

Methods: A prospective observational cohort study was performed. All emergency cranial neurosurgical ward admissions from 1st January to 10th May 2017 were screened for inclusion (n = 406). Patients already receiving vitamin D supplementation, spinal patients and elective admissions were excluded. Admission vitamin D levels were checked for all remaining patients (n = 95). Patients with vitamin D <30 nmol/L were defined as "deficient" and those 30-50 nmol/L as "inadequate." All patients with levels <50 nmol/L were replaced, as per local guidelines. Descriptive analyses of the cohorts were undertaken, with multivariate regression used to assess the effect of vitamin D on length of stay, inpatient morbidity and mortality.

Results: The median age of participants was 61 years (n = 95; 57% male, 43% female). The median vitamin D level was 23 nmol/L (deficient). 84% (n = 80) of patients had low vitamin D levels, with 61% (n = 58) classed as deficient (<30 nmol/L). Vitamin D deficiency rates were similar in those aged below 65 years (86%; n = 38/44) and those above 65 years (82%; n = 42/51). Deficient vitamin D level was associated with longer hospital stay (P = .03), and this relationship persisted after adjusting for potential confounders such as age, sex and preadmission Charlson co-morbidity index. No statistically significant association was seen with vitamin D status and inpatient morbidity or mortality.

Conclusions: Vitamin D deficiency is common in cranial neurosurgical patients, even in predefined low-risk groups (age <65). Lower vitamin D level was associated with longer length of stay. This study supports the need for: (a) further investigation into the roles of vitamin D in neurosurgical pathologies and management and (b) an appropriately powered, randomised investigation into the impact of vitamin D status upon neurosurgical diagnoses and complications.

Keywords: neuroendocrinology; neurosurgery; surgery; vitamin D.

Figure 1

Flowchart outlining the study methodology

Figure 2

Histogram of vitamin D levels on admission. The majority of patients in the cohort had inadequate (30‐50 nmol/L) or deficient (<30 nmol/L) vitamin D level on admission

Figure 3

The distribution of vitamin D deficiency amongst varying pathologies in the study cohort. The majority of patients with emergency neurosurgical conditions were identified to have low vitamin D levels. ASDH, Acute subdural haematoma; CSDH, Chronic subdural haematoma; EDH, Extradural haematoma; ICH, intracerebral haemorrhage; SAH, Subarachnoid haemorrhage; SOL, space occupying lesion; TBI, traumatic brain injury

Figure 4

Box plot showing the effect of vitamin D on the median length of stay (LOS). Low (inadequate or deficient) vitamin D was significantly associated with a longer inpatient LOS in the neurosurgical unit compared to vitamin D replete patients (16 days Vs 13 days). Normal vitamin D: serum 25‐hydroxy vitamin D >50 nmol/L. Inadequate or deficient (low) vitamin D: serum 25hydroxy vitamin D ≤50 nmol/L. LOS, length of stay