Hemoglobin A1c as a Predictor of Postoperative Infection Following Elective Forefoot Surgery.

Abstract

There remains little evidence to support a perioperative hemoglobin A1c (HbA1c) level that could serve as a threshold for a significantly increased risk of postoperative surgical site infection (SSI) following forefoot surgery. A national database was queried for patients who underwent elective forefoot surgery with diabetes. Patients with a perioperative HbA1c level within 3 months of surgery were identified and stratified based on HbA1c level in 0.5 mg/dL increments. The incidence of SSI was determined by either a diagnosis or procedure for SSI within 1 year and a receiver operating characteristic (ROC) curve and area under the curve (AUC) analysis was performed to determine an optimal threshold value of HbA1c. A total of 4630 patients who underwent forefoot surgery with diabetes with a perioperative HbA1c were included. The rate of SSI ranged from 2.3% to 11.8%. The inflection point of the ROC curve corresponded to an HbA1c level above 7.5 mg/dL ( P < .0001; 95% confidence interval [CI] = 0.58-0.67; AUC = 0.631; specificity = 75%; sensitivity = 46%). After multivariate analysis, patients with an HbA1c level of 7.5 mg/dL or greater had a significantly higher risk for postoperative wound infection compared to patients below this threshold (OR = 1.92; 95% CI = 1.5-2.4; P < .0001). The risk of postoperative SSI following forefoot surgery increased as the perioperative HbA1c increased. ROC analysis determined that a perioperative HbA1c above 7.5 mg/dL could serve as a threshold for a significantly increased risk of postoperative SSI following forefoot surgery. Level III, comparative series.