The association of preoperative haemoglobin A1c with 30-day postoperative surgical site infection following non-cardiac surgery

Abstract

Diabetes has been shown to be associated with postoperative infections; however, the association of haemoglobin A1c (HbA1c) with postoperative surgical site infections (SSI) is unclear. All HbA1c data from patients receiving general, vascular, or orthopaedic surgeries between 1 January 2014 and 1 December 2016 were identified from hospital records. The primary outcome was 30-day SSI. Multivariable logistic regression was performed to determine if HbA1c was associated with infection. The cohorts assessed were: (1) HbA1c < 6.5% (reference group); (2) greater than or equal to 6.5% and less than 8.0%; (3) greater than or equal to 8.0% and less than 10.0%; and (4) greater than or equal to 10.0%. There were 3064 patients included in the final analysis. The overall rate of 30-day SSI was 2.42%. After adjusting for confounders, when compared to the reference group, HbA1c ≥ 8.0% and less than 10.0% (OR 2.4, 95% CI 1.2–4.7, p = 0.015) and HbA1c ≥ 10.0% (OR 3.0, 95% CI 1.2–7.3, p = 0.016) had increased odds ratio for 30-day SSI. A HbA1c of 8.0% or higher significantly increased the odds ratio of developing postoperative SSI (p < 0.05). This may aid in the development of guidelines for optimising diabetic patients.