Introduction: Diabetes mellitus (DM) is a prevalent disease of glucose dysregulation that has been associated with an increased risk for postoperative infection following spine surgery. The status of preoperative blood glucose management may affect the risk of surgical site infection (SSI). In the present study, we evaluated the association between preoperative glycemic control as indicated by hemoglobin A1c (HbA1c) in patients with diabetes and incidence of postoperative SSI following single level lumbar/lumbosacral posterior fusion.
Methods: From January 2009 to December 2015, total 92 patients who underwent single level lumbar/lumbosacral posterior fusion with diabetes and had preoperative HbA1c recorded within 4 weeks of surgery were included in the study. Patients were divided into two groups according to whether they had SSI, and then demographic/clinical data were compared. A receiver operating characteristic (ROC) and area under the curve (AUC) analysis was conducted to define the cut-off value of HbA1c above which the risk of SSI was significantly increased. Including this value, potential variables were verified by multiple logistic regression analysis.
Results: Twenty four patients were treated for SSI and 68 patients maintained noninfectious condition within 1 year. Three of the 24 (12.5%) patients developed SSI in the deep layer requiring operative irrigation and debridement. The preoperative HbA1c value was significantly higher in patients with SSI (6.8%) than in those without SSI (6.0%; p=0.008). The results of ROC analysis determined that HbA1c = 6.9% could serve as a threshold for significantly increased risk of SSI (p=0.003, AUC=0.708, sensitivity=62.5%, specificity=70.6%). After adjusting for confounding factors, there was a significant association between preoperative HbA1c and occurrence of SSI (p=0.008, OR=4.500).
Conclusions: : In patients with diabetes, the preoperative glycemic control as indicated by HbA1c is an independent risk factor for SSI following single level lumbar/lumbosacral posterior fusion. Particularly when preoperative HbA1c exceeded 6.9%, the risk of SSI significantly increased.
Patient Care: The influence of DM on infection after single level lumbar fixation was evaluated in detail.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of the association between preoperative glycemic control, as indicated by HbA1c, in patients with diabetes and incidence of postoperative SSI following single level lumbar/lumbosacral posterior fusion and 2) identify a threshold level of HbA1c above which the risk of SSI after posterior lumbar/lumbosacral arthrodesis increases significantly in diabetic patients.