Is There a Threshold Value of Hemoglobin A1c That Predicts Risk of Infection Following Primary Total Hip Arthroplasty?

Abstract

There remains little evidence to support a perioperative hemoglobin A1c (HbA_1c) level that could serve as a threshold for a significantly increased risk of deep postoperative infection in patients with diabetes mellitus (DM) following total hip arthroplasty (THA). A national administrative database was queried for patients who underwent primary THA with DM. Patients with an HbA_1c level within 3 months of surgery were identified and were stratified based on HbA_1c level in 0.5 mg/dL increments. The incidence of deep infection requiring operative intervention within 1 year for each group was identified and a receiver operating characteristic (ROC) and area under the curve (AUC) analysis was performed to determine a threshold value of the HbA_1c. A total of 7736 patients who underwent THA with a perioperative HbA_1c level were included. The rate of infection ranged from 0.7% to 5.9%. The inflection point of the ROC curve corresponded to an HbA_1c level between 7.0 and 7.5 mg/dL (P = .001, specificity = 69%, sensitivity = 47%). The AUC for the ROC was 0.68. Patients with an HbA_1c level of 7.5 mg/dL or greater had a significantly higher risk of deep infection compared to patients below this threshold (odds ratio, 2.6; 95% CI, 1.9-3.4; P < .0001). The risk of infection in patients with DM increases as the perioperative HbA_1c increases. However, in the present study, the HbA_1c threshold level calculated demonstrated low discrimination based on our AUC value, suggesting the HbA_1c test is poorly predictive of periprosthetic joint infection following THA in patients with DM.