Glycated Hemoglobin as a Predictor of Postoperative Delirium in Diabetic Patients Undergoing Noncardiac Surgery: A...

Background and Objectives: Diabetes is a known risk factor for postoperative delirium (POD); however, the relationship between the markers of glycemic control and the occurrence of POD in noncardiac surgery is not established. We initiated this pilot study to determine any possible associations between preoperative HbA1c levels and POD development; this will allow for larger, definitive studies to be designed and preliminary effect sizes to be established for future research. Materials and Methods: This retrospective pilot study included 78 patients with diabetes who underwent elective noncardiac surgery under general anesthesia between July 2020 and January 2021. We obtained the patients' demographic data, medical history, surgical parameters, and preoperative HbA1c levels to determine the occurrence of POD (using CAM-ICU). Univariate and multivariate regression analyses were applied to check the leading associations for the development of POD. Results: POD was observed in seven patients (9.0%). The results of the preliminary multivariate analysis suggested that HbA1c may be associated with POD (OR, 2.96; 95% CI [1.34-6.52], p = 0.007); fasting blood glucose (OR, 1.04; 95% CI [1.01-1.07], p = 0.013); and duration of anesthesia (OR, 1.02; 95% CI [1.00-1.04], p = 0.019). The ROC analysis of HbA1c showed an optimal threshold of 7.4%, with a sensitivity of 91.5%, and a specificity of 85.7% in terms of predicting POD (AUC = 0.91, p < 0.001). Conclusions: Through this pilot study, we have provided evidence that leads to the assumption that preoperative HbA1c at, or above, 7.4% can result in an increased risk of delirium in diabetic patients who undergo noncardiac surgery. The findings of this study allow for the implementation of the proposed methodology and the collection of critical data necessary for the design of appropriately powered definitive trials.