Preoperative vitamin D status and its effects on short-term clinical outcomes in lumbar spine surgery

Many studies have found that vitamin D deficiency has a high incidence rate worldwide, but we found few studies on the role of vitamin D in spinal degenerative diseases. We investigated the determinants of preoperative vitamin D deficiency and its effects on postoperative outcomes among patients undergoing elective lumbar spine surgery.

360 patients treated from July 2017 to July 2018 were retrospectively identified for inclusion. The patients' fasting serum levels of 25(OH)D, N-terminal midfragment of osteocalcin (N-MID), and β typeⅠcollagen carboxyl terminal peptide (β-CTX) were measured by electrochemiluminescence before the operation. The visual analogue scale (VAS), Japanese Orthopaedic Association (JOA) and Oswestry Disability Index scores (ODI) were used to evaluate the clinical outcomes. Standard demographic data and all perioperative complications occurring within 3 months follow-up after operation were recorded.

The mean serum level of 25(OH)D was 20.81 ± 8.55 ng/mL, the rates of deficiency (<20 ng/ml) was 53.6%. The abnormal proportion of N-MID and β-CTX were 8.61% and 34.44%, bone turnover markers serum level was higher in older age groups (p < 0.05). Female sex (p < 0.001), a high body mass index (BMI) (p = 0.012), lack of vitamin D supplementation (p = 0.018), smoking (p = 0.033), moderate (p < 0.001) to severe pain (p = 0.005) were significant predictors of vitamin D deficiency after the multivariate analysis. The VAS, JOA and ODI scores showed significantly better outcomes compared to deficient group at post-operative and final follow-up (p < 0.05).

Vitamin D deficiency was common in patients undergoing elective lumbar spine surgery. Female sex, high BMI, lack of vitamin D supplementation, smoking and moderate to severe pain were risk factors for vitamin D deficiency. Moreover, preoperative hypovitaminosis D (<20 ng/ml) was correlated with worse surgical outcomes in short-term.