RT Journal Article SR Electronic T1 The Effect of Vitamin D Deficiency on Outcomes of Patients Undergoing Elective Spinal Fusion Surgery: A Systematic Review and Meta-Analysis JF International Journal of Spine Surgery JO Int J Spine Surg FD International Society for the Advancement of Spine Surgery SP 53 OP 60 DO 10.14444/8177 VO 16 IS 1 A1 Razieh Khalooeifard A1 Jamal Rahmani A1 Roozbeh Tavanaei A1 Oladimeji Adebayo A1 Mohsen Keykhaee A1 Amirahmad Ahani A1 Alireza Zali A1 Zahra Vahdat Shariatpanahi A1 Saeed Oraee-Yazdani YR 2022 UL http://ijssurgery.com//content/16/1/53.abstract AB Objectives Vitamin D plays a major role in bone metabolism, regulating calcium and phosphorus homeostasis, along with bone growth and remodeling processes. The objective of the present study was to assess the effect of vitamin D deficiency on clinical outcomes following elective spinal fusion surgery by conducting a meta-analysis on the relevant literature.Methods Studies included in this analysis involved patients older than 18 years who underwent elective spinal fusion surgery. The number of patients as well as visual analog scale (VAS) and Oswestry Disability Index (ODI) in groups with and without vitamin D deficiency were required to be reported in eligible studies. Of the 179 articles identified, 7 met the inclusion criteria and were included in the analysis.Results Seven studies, including 1188 patients, reported the relationship between vitamin D deficiency and clinical outcomes in patients undergoing elective spinal fusion surgery. Five studies reported VAS as a primary outcome. The combined results using a random-effects model showed reduction in VAS after elective spinal fusion surgery in group with vitamin D deficiency, but no statistically significant association was identified between vitamin D deficiency and VAS. ODI was assessed and reported as an outcome measure in 5 of the included studies. The combined results showed an increase in ODI following elective spinal fusion surgery in the vitamin D-deficient group compared to the group with normal levels of vitamin D. In addition, a significant association was observed between ODI and vitamin D deficiency.Conclusions Vitamin D deficiency may negatively affect the postoperative outcomes in elective spinal fusion surgery. Preoperative optimization of vitamin D levels would seem appropriate. Future high-quality studies are highly warranted to evaluate this.Clinical Relevance This meta-analysis demonstrated a significant association between vitamin D deficiency and postoperative ODI scores in patients undergoing elective spinal fusion surgery.Level of Evidence 2.