Association of individualized versus conventional blood glucose thresholds with acute kidney injury after cardiac surgery: A retrospective observational study

Objectives To compare individualized and conventional hyperglycemic thresholds for the risk of acute kidney injury (AKI) after cardiac surgery. Design Observational study. Setting Tertiary teaching hospital, single-center Participants Adult patients who underwent cardiac surgery between January 2012 and November 2021. Measurements and Main Results Two separate blood glucose thresholds were used to define intraoperative hyperglycemia. While the conventional hyperglycemic threshold (CHT) was 180 mg/dL in all patients, the individualized hyperglycemic threshold (IHT) was calculated based on the preoperative hemoglobin A1c level. Various metrics of intraoperative hyperglycemia were calculated using both thresholds: any hyperglycemic episode, duration of hyperglycemia, and area above the thresholds. Postoperative AKI associations were compared using receiver operating characteristic curves and logistic regression analysis. Among the 2,427 patients analyzed, 823 (33.9%) developed AKI. The c-statistics of IHT-defined metrics (0.58–0.59) were significantly higher than those of the CHT-defined metrics (all c-statistics, 0.54; all P <0.001). The duration of hyperglycemia (adjusted odds ratio, 1.09; 95% confidence interval, 1.02–1.16) and area above the IHT (1.003; 1.001–1.004) were significantly associated with the risk of AKI, except for the presence of any hyperglycemic episode. None of the CHT-defined metrics were significantly associated with the risk of AKI. Conclusions Individually defined intraoperative hyperglycemia better predicted post-cardiac surgery AKI than universally defined hyperglycemia. Intraoperative hyperglycemia was significantly associated with the risk of AKI only for the IHT. Target blood glucose levels in cardiac surgical patients may need to be individualized based on preoperative glycemic status.