199. HbA1c and BMI are modifiable risk factors for reducing wound complications but do not influence risk of pseudarthrosis

BACKGROUND CONTEXT Patients with diabetes mellitus (DM) undergoing posterior spinal fusion (PSF) with elevated HbA1cs are at higher risk of postoperative complications than those with lower HbA1cs. DM patients with an HbA1c >7.05% are prone to postoperative complications such as wound complications (WC). Pseudarthrosis (PA) is another complication for PSF and requires further insight in determining risk factors for DM. PURPOSE To determine if DM patients with higher preoperative HbA1c levels will have higher rates of WC and PA. STUDY DESIGN/SETTING Single-center retrospective cohort study. PATIENT SAMPLE This study included 229 DM patients. OUTCOME MEASURES Patient demographics, osteopenia, preoperative HbA1c, WC, PA, and levels-fused (LF). METHODS Included: DM patients undergoing thoracolumbar PSF from 2014-2019 with preoperative HbA1C levels, and a minimum 1-year postoperative follow-up. PA was defined by the treating surgeon via clinical presentation, radiographs and postoperative CT scan with minimum 1-year postoperative interval. WC included dehiscence, seroma requiring aspiration or infection of the surgical site.  Excluded: Patients undergoing LLIFs and ALIFs or diagnosed with prior pars fracture, spinal tumor, ankylosing spondylitis, fracture and infection. Relationships between complications and HbA1c were determined using t-test, chi-squared analyses and multivariate regressions (α=0.05). In risk factors, the cutoff HbA1C value as a predictor for multiple postoperative complications was identified via receiver operating characteristic (ROC) analyses using Youden's index. RESULTS A total of 229 patients met these criteria. Age (Normal: 65.4±11.0, PA: 63.0±8.2, p=0.249; Normal: 65.2±10.6, WC: 64.5±9.7, p=0.753), CCI (Normal: 4.6±2.0, PA: 4.0±1.2, p=0.06; Normal: 4.6±1.9., WC: 4.6±1.7, p=0.761), gender, percent female, (Normal: 57%, PA: 47%, p=0.286; Normal: 55%, WC: 58%, p=0.829), osteopenia (Normal: 3%, PA:3%, p=0.968; Normal: 3%, WC: 0.0%, p=0.377), and smoker status (Normal: 11%, PA: 16%, p=0.44; Normal: 11%, WC: 12%, p=0.915) did not have a significant impact in the tested postoperative complications. Mean HbA1c (7.6±1.5%, p=0.001), LF (3.9±3.2, p=0.024) and BMI (35.8±7.4, p=0.004) in patients with WC were significantly higher than those without WC (HbA1C: 6.8±1.0%; LF: 2.5±2.9 BMI: 31.7±6.7). HbA1c (OR: 1.7 [1.2-2.5], p=0.005), BMI (OR: 1.1 [1.0-1.2], p=0.007) and LF (OR: 1.1[1.1-1.3], p=0.031) was an independent risk factor WC. In those with PA, mean HbA1c (7.0±1.3, p=0.289) was not significantly higher than those without PA (HbA1C:7.0±1.1). HbA1c (OR: 1.039 [0.73-1.478], p=0.831) was not an independent risk factor for PA.ROC analyses demonstrated HbA1c>7.05% (AUC: 0.693[0.587-0.800], p=0.001], BMI>32.92 (AUC: 0.664[0.555-0.772], p=0.007) and >1.5 LF (AUC: 0.626[0.502-0.750], p=0.036) as fair predictive models for WC. CONCLUSIONS Preoperative HbA1C>7.05%, BMI>32.92 and LF>1.5 are independent risk factors of WC; however, neither of these are predictors for PA in diabetics who had PSF. Regardless, DM patients undergoing PSF should strive to lower their HbA1c FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.