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

Abstract

Background: There remains little evidence to support a perioperative hemoglobin A_1c (HbA_1c) level that could serve as a threshold for a significantly increased risk of postoperative surgical site infection (SSI) following forefoot surgery.

Methods: A national database was queried for patients who underwent elective forefoot surgery with diabetes. Patients with a perioperative HbA_1c level within 3 months of surgery were identified and stratified based on HbA_1c 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 HbA_1c.

Results: A total of 4630 patients who underwent forefoot surgery with diabetes with a perioperative HbA_1c were included. The rate of SSI ranged from 2.3% to 11.8%. The inflection point of the ROC curve corresponded to an HbA_1c 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 HbA_1c 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).

Conclusions: The risk of postoperative SSI following forefoot surgery increased as the perioperative HbA_1c increased. ROC analysis determined that a perioperative HbA_1c above 7.5 mg/dL could serve as a threshold for a significantly increased risk of postoperative SSI following forefoot surgery.

Level of evidence: Level III, comparative series.

Keywords: HbA1c; diabetes; forefoot disorders; hallux disorders; outcome studies.