The Association of Perioperative Glycemic Control with Deep Postoperative Infection After Anterior Cervical Discectomy and Fusion in Patients with Diabetes

Objective To evaluate the association of perioperative hemoglobin A_1c (HbA_1c) level in patients with diabetes with the incidence of infection after anterior cervical discectomy and fusion requiring operative intervention, in addition to determining if a threshold level of HbA_1c above which the risk of infection increases significantly exists. Methods A national administrative database was queried for patients who underwent primary anterior cervical discectomy and fusion with diabetes who had a perioperative HbA_1c level recorded within 3 months of surgery. These patients were stratified based on their HbA_1c level in 0.5-mg/dL increments from <5.49 mg/dL to >11.5 mg/dL. The incidence of infection requiring operative intervention within 1 year was then identified using Current Procedural Terminology and International Classification of Diseases, Ninth Revision codes. A receiver operating characteristic (ROC) analysis was performed to determine a threshold value of the HbA_1c level. Results A total of 3341 patients with a perioperative HbA_1c level were included. The rate of deep infection requiring irrigation and debridement postoperatively stratified by HbA_1c level ranged from a low of 1.5% to a high of 6.4% and was significantly correlated with increasing HbA_1c levels (P = 0.005). The results of ROC analysis determined that the inflection point of the ROC curve corresponded to an HbA_1c level higher than 7.5 mg/dL (P = 0.022; area under the curve, 0.67; specificity, 68%; sensitivity, 46%). Conclusions The risk of deep postoperative infection in patients with diabetes mellitus increases as the perioperative HbA_1c level increases. ROC analysis determined that a perioperative HbA_1c level higher than 7.5 mg/dL could serve as a threshold for a significantly increased risk of infection.