244. Relationship between 25-hydroxy vitamin D level and surgical site infection in spine surgery

BACKGROUND CONTEXT Surgical site infection (SSI) creates a significant burden on the patient and the health care system. Preoperative medical optimization, antibiotics have been incorporated in standard practice reduce perioperative complications, and many others are currently under investigation. In animal models, 25-hydroxy vitamin D level has been shown to have antimicrobial and wound healing effects. Preoperative levels have been shown to correlate with SSI in thoracic and bariatric surgeries. However, to date it has not been evaluated in spine patients. PURPOSE To investigate whether low vitamin D status is associated with increased risk of developing post-operative infections in spine surgeries. STUDY DESIGN/SETTING Retrospective PATIENT SAMPLE Patients undergoing thoracolumbar spine surgery between November 2012 and March 2019 performed by one fellowship-trained orthopedic spine surgeon at a single academic center. OUTCOME MEASURES The outcome variable was SSI undergoing surgical intervention. METHODS We identified all patients within the stated sample and enrolled only patients with preop vitamin D levels. SSI, age, BMI, season of surgery, race, type of surgery, diagnosis, ASA, smoking status were extracted. The key independent variable was Vit D level (classified as 60 ng/mL= Potentially Harmful). Bivariate analysis with chi-square and t-tests were used to compare characteristics between the non-SSI and SSI cohorts undergoing spine surgery. Multivariable logistic regression analyses were used to determine associations between vitamin D levels and SSIs after controlling for relevant confounders such as BMI, type of surgery, diagnosis, comorbidities. RESULTS A total of 545 patients met our inclusion criteria, 9 (1.7%) of which acquired an SSI. The mean 25-Hydroxy vitamin D was 31.6 ± 13.6 ng/dL in non-SSI group, and 35.7 ± 20.2 ng/dL in SSI group (p-value 0.17). The mean age was 56 ± 15.6 years in the non-SSI group and 64 ± 7.5 years in the SSI group (p- value 0.045). 21.7% of non-SSI patients had moderate risk of vitamin D deficiency, 27.9% had low risk of deficiency, 46.8% had adequate levels and 3.6% had potentially harmful levels. 33.3% of non-SSI patients had moderate risk of Vitamin D deficiency, 11.1% had low risk of deficiency, 33.3% had adequate levels and 22.2% had potentially harmful levels (p-value 0.02). On bivariate analysis, the percentage of patients with potentially harmful levels of Vitamin D in the SSI group was higher than in the non-SSI group (22.2% and 3.6% respectively, p-value 0.02). On multivariable analysis, patients with adequate vitamin D level had lower odds of SSI as compared to vitamin D deficient patients (OR 0.11, CI 0.01-0.98, p-value 0.048). Though not statistically significant, patients with potentially harmful vitamin D level were at higher odds of SSI (OR 1.41, CI 0.11-17.34, p-value 0.79). CONCLUSIONS Our analysis showed that patients with adequate levels of vitamin D has lower risk of SSIs as compared to vitamin D deficient patients after controlling for relevant confounders. Optimizing preop vitamin D levels could potentially reduce the incidence of SSI in spine surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.