Study design: Retrospective investigation of cross-sectional data.
Objective: To define the prevalence and determinants of preoperative vitamin D deficiency among adults undergoing spinal fusion.
Summary of background data: Vitamin D plays a critical role in establishing optimal bone health, which, in turn, is vital to the success of spinal arthrodesis. Recently, hypovitaminosis D was documented in 43% of adults undergoing any orthopedic surgery.
Methods: Serum 25-hydroxyvitamin D levels were routinely measured in adults undergoing spinal fusion at a single institution. Between January 2010 and March 2011, 313 patients were retrospectively identified for inclusion. Risk factors for vitamin D deficiency (<20 ng/mL) were analyzed using univariate analysis and multivariate logistic regression.
Results: The rates of inadequacy (<30 ng/mL) and deficiency were 57% and 27%, respectively. Although 260 patients were diagnosed with degenerative disease (spondylosis), 99 had deformity, and there were 73 revision cases. There was a higher rate of smoking (P = 0.03) and lower age (P < 0.01) in the vitamin D-deficient subset. There was no sex difference. Increasing body mass index (P < 0.01), increasing Neck and Oswestry Disability Index scores (P = 0.03), and lack of vitamin D and/or multivitamin supplementation (P < 0.01) remained predictors of deficiency after multivariate analysis. Those with previous supplementation were older (P < 0.01) and more likely to be at least 50 years old than those without repletion (P < 0.01).
Conclusion: Our investigation revealed a substantially high prevalence of vitamin D abnormality in the analyzed population. Although advanced age is a well-established risk factor for hypovitaminosis, young adults undergoing fusion should not be overlooked with regard to vitamin D screening; this age bracket is less likely to have been previously supplemented. In the absence of better-recognized determinants, spinal disability indices may also be useful in identifying those with deficiency.