Importance of Hemoglobin A1c Levels for the Detection of Post-Surgical Infection Following Single-Level Lumbar Posterior Fusion in Patients with Diabetes

OBJECTIVE: Several studies have reported that patients with diabetes mellitus (DM) are vulnerable to infection. However, the mechanism underlying this remains unclear. We hypothesized that preoperative blood glucose levels in patients with DM may be a risk factor for surgical site infection (SSI). We aimed to investigate the relationship between hemoglobin A1c (HbA1c) level and SSI incidence following single-level spinal fusion surgery. METHODS: Patients with DM who underwent single-level lumbar posterior fusion surgery were retrospectively reviewed. Ninety-two patients were included and classified into the SSI and SSI-free groups. Clinical data with demographic findings were obtained and compared. The HbA1c cut-off value was defined using receiver operating characteristic (ROC) and area under the curve (AUC) analyses, which showed a significantly increased SSI risk. Potential variables were verified using multiple logistic regression analysis. RESULTS: Among the enrolled patients, 24 had SSI and 68 did not within 1 year. The preoperative HbA1c level was higher in patients with SSI (6.8%) than in the non-infected patients (6.0%; p=0.008). ROC analysis showed that if the HbA1c level is higher than 6.9%, the risk of SSI significantly increases (p=0.003; AUC, 0.708; sensitivity, 62.5%; specificity, 70.6%). The preoperative HbA1c level was significantly correlated with SSI incidence, after adjusting for potential variables (p=0.008; odds ratio, 4.500; 95% confidence interval, 1.486–13.624). CONCLUSION: The HbA1c level, indicating glycemic control, in patients with DM may be a risk factor for SSI in single-level lumbar spine posterior fusion.