Effect of pre-operative HbA1c and blood glucose level on the surgical site infection after lumbar instrumentation surgery.

Background: This study aims to investigate the effect of pre-operative hemoglobin A1c (HbA1c) and pre-operative blood glucose control on the rate of surgical site infection (SSI) after posterior lumbar instrumentation surgery in diabetes mellitus (DM) patients.

Methods: A total of 1046 patients who had undergone posterior lumbar instrumentation surgery were reviewed. Based on pre-operative HbA1c, patients were divided into three groups: non-DM group, low HbA1c group (HbA1c < 7.0 % in DM) and high HbA1c group (≥7.0). As well, based on the status of blood glucose control in DM patients immediately before surgery, patients were divided into two groups: good control group (post-prandial blood glucose [PBG] < 200 mg/dl) and poor control group (≥200). The rate of SSI was compared among these groups.

Results: SSI occurred in 1.9 % in non-DM group, 2.4 % in low HbA1c group, and 9.3 % in high HbA1c group. Compared with non-DM group, high HbA1c group had significantly higher rate of SSI (p = 0.001). There was not statistically different between non-DM and low HbA1c groups (p = 0.550). SSI occurred in 2.2 % in good control group, and 10.2 % in poor control group. The rate of SSI was significantly lower in good control group (p = 0.013).

Conclusion: This study showed that the rate of SSI after posterior lumbar instrumentation surgery tend to be higher in DM patients with high HbA1c. However, the rate might be reduced to the same level as that of non-DM group by lowering PBG to <200 mg/dl immediately before surgery.