Peer-Review ReportPrevalence of Vitamin D Deficiency in Patients Undergoing Elective Spine Surgery: A Cross-Sectional Analysis
Introduction
Decreased bone density secondary to osteoporosis and osteomalacia represents a serious risk factor for both bony fracture and spinal instrumentation failure 5, 8, 11, 21, 24. One of the most common and potentially treatable causes of pseudarthrosis or instrumentation failure in patients undergoing spinal fusion is poor bone mineral density (BMD) resulting from age-related vertebral osteoporosis (7). Numerous studies have shown that low serum vitamin D levels lead to greater bone resorption and turnover, predisposing patients to vertebral osteoporosis 14, 22, 23.
The National Osteoporosis Foundation estimates that 52 million Americans have osteoporosis or low bone mass (http://nof.org/articles/7), whereas an estimated 25%–57% of adults living in the United States have a deficiency of vitamin D 10, 12. Osteoporosis is a bony condition defined by a decreased density of normally mineralized bone. Reduced bone density compromises the mechanical strength of bone, increasing the risk of bony fracture (11). Vitamin D is a secosteroid that plays a key role in bone and calcium metabolism. The active form of vitamin D is vitamin D3 (cholecalciferol). The cutaneous synthesis of vitamin D3 is the major source of vitamin D. Cutaneous vitamin D3, along with that from nutritional sources, is conjugated in the liver to 25(OH) vitamin D and the kidneys to the active form of 1,25(OH)2 vitamin D (20). Vitamin D causes increased calcium absorption from the intestines and the kidneys and acts on osteoblasts to increase BMD (Figure 1) (20).
Nearly one third of patients older than 50 years of age undergoing spinal surgery have osteoporosis (5). Stoker et al. (26) demonstrated an insufficiency rate of 57% and a deficiency rate of 27% in preoperative 25-OH vitamin D levels in 313 patients undergoing elective spinal fusion. Despite this high incidence of osteoporosis and its association with serum vitamin D, the preoperative assessment of BMD and vitamin D levels is not routine among most spinal surgeons (7). Although there is a clear link between BMD and the risk of osteoporosis, it is not clear whether aggressive treatment of low vitamin D levels leads to improved spinal fusion and decreased incidence of instrumentation failure. With increased scrutiny of all spinal fusion procedures, low-cost testing that helps predict the potential risk for subsequent nonfusion and need for revision surgery may have substantial cost-saving benefits. Because of the compelling evidence suggesting a high incidence of unrecognized vitamin D deficiency, studies examining the precise role of these measures in humans undergoing spinal fusion procedures are necessary (26).
In the present study, we evaluated the incidence of vitamin D deficiency in patients scheduled to undergo elective spinal instrumentation procedures to investigate which patient-level factors are associated with deficient vitamin D levels. The information gathered will provide an understanding of risk factors and will allow surgeons an opportunity to preoperatively assess bony health and metabolism before surgery.
Section snippets
Patient Population
A cross-sectional observational analysis was designed to evaluate patients undergoing elective spinal fusion at a single academic, tertiary referral institution between November 2011 and December 2012. The Institutional Review Board approved the study. Patients older than 18 years undergoing elective spinal fusion were eligible. To maintain population uniformity, patients with traumatic spinal fracture or injury treated with stabilization were excluded. Vitamin D levels were assessed in all
Patient Characteristics
Two hundred thirty patients underwent elective spine surgery during the study period. The mean age of the patients was 57 ± 13.9 years (range, 18–90 years), with 42.2% of patients older than 60 years (Table 1). More than half (56.1%) of the population were men, and nearly all patients were white (95.9% of 221 patients). BMI was categorized into three groups, <30 representing nonobese patients, 30–40 indicating obesity, and >40 signifying morbidly obese; the mean BMI of the 223 patients for whom
Discussion
In 2006, approximately 343,000 spinal fusion procedures were performed in the United States alone. A common and potentially treatable cause of delayed complication after spinal fusion is pseudarthrosis and spinal instrumentation failure (19). Although pseudarthrosis or instrumentation failure cannot always be linked to a single entity, a known contributor is poor BMD or osteoporosis (9). Decreased BMD is a known predictor of instrumentation failure, and with an aging population, an increased
Acknowledgments
We thank Kristin Kraus, M.Sc., for editorial assistance in preparing this article, Jennie Williams, M.F.A., for illustrations, and Richard H. Schmidt, M.D., Ph.D., and Joel D. MacDonald, M.D., for their participation in this study.
References (26)
- et al.
Hypovitaminosis D is associated with insulin resistance and beta cell dysfunction
Am J Clin Nutrition
(2004) - et al.
Survey of spine surgeons on attitudes regarding osteoporosis and osteomalacia screening and treatment for fractures, fusion surgery, and pseudoarthrosis
Spine J
(2009) - et al.
Revision strategies for lumbar pseudarthrosis
Orthop Clin North Am
(2002) - et al.
Prevalence and correlates of vitamin D deficiency in US adults
Nutr Res
(2011) High prevalence of vitamin D inadequacy and implications for health
Mayo Clinic Proc
(2006)- et al.
Prevalence of vitamin D deficiency in patients with lumbar spinal stenosis and its relationship with pain
Pain Physician
(2013) - et al.
Vitamin D deficiency an important, common, and easily treatable cardiovascular risk factor?
J Am Coll Cardiol
(2008) - et al.
Role of vitamin D in cardiovascular health
Am J Cardiol
(2010) - et al.
Revision lumbar surgery in elderly patients with symptomatic pseudarthrosis, adjacent-segment disease, or same-level recurrent stenosis. Part 2. A cost-effectiveness analysis: clinical article
J Neurosurg Spine
(2013) - et al.
Hypovitaminosis D in patients scheduled to undergo orthopaedic surgery: a single-center analysis
J Bone Joint Surg Am
(2010)
Vitamin D3 and calcium to prevent hip fractures in the elderly women
N Engl J Med
Prevalence of vitamin D insufficiency in an adult normal population
Osteoporos Int
Prevalence of osteoporosis in patients requiring spine surgery: incidence and significance of osteoporosis in spine disease
Osteoporos Int
Cited by (0)
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.