Longitudinal hemoglobin trajectories and acute kidney injury in patients undergoing cardiac surgery: a retrospective cohort study

Abstract

ObjectThe purpose of this study was to describe the longitudinal dynamic hemoglobin trajectories in patients undergoing cardiac surgery and to explore whether they provide a broader perspective in predicting AKI compared to traditional threshold values. Additionally, the interaction of red blood cell transfusion was also investigated.MethodsThe MIMIC-IV database was searched to identify patients undergoing cardiac surgery with cardiopulmonary bypass. Group-based trajectory modeling (GBTM) was used to determine the hemoglobin trajectories in the first 72 h after ICU admission. The correlation between hemoglobin trajectories and AKI was evaluated using multivariable logistic regression and inverse probability of treatment weighting. Receiver operating characteristic (ROC) curves were created in the dataset to further validate previously reported thresholds.ResultsA total of 4,478 eligible patients were included in this study. Three hemoglobin trajectories were identified by GBTM, which were significantly different in the initial hemoglobin level and evolution pattern. Compared to the “the lowest, rising, and then declining” trajectory, patients in the “the highest, declining” and “medium, declining” trajectory groups had significantly lower AKI risk (OR 0.56; 95% CI 0.48, 0.67) and (OR 0.70; 95% CI 0.55, 0.90), respectively. ROC analysis yielded a disappointing result, with an AUC of 0.552, sensitivity of 0.25, and specificity of 0.86 when the hemoglobin threshold was set at 8 g/dl in the entire cohort. In the subgroup analysis of red blood cell transfusion, hemoglobin levels above 10 g/dl predicted higher AKI risk, and there was no correlation between hemoglobin trajectories and AKI in the non-red blood cell transfusion subgroup.ConclusionThis study identified a hemoglobin trajectory that is associated with an increased risk of AKI after cardiac surgery. It is noteworthy that fixed hemoglobin thresholds should not be applied to all patient types. In patients receiving red blood cell transfusion, maintaining hemoglobin levels above 10 g/dl through transfusion was associated with an increased risk of AKI.

Development of interpretable machine learning models for prediction of acute kidney injury after noncardiac surgery: a retrospective cohort study

“…In regard to blood transfusion, preoperative anemia is a risk factor for postoperative AKI, but blood transfusion itself increases the risk of postoperative AKI 55 . Therefore, individualized blood transfusion plans need to be developed based on a patient’s condition 56 , 57 .…”

Association of hemoglobin level trajectories with clinical outcomes in patients with sepsis or shock: a retrospective observational study

“…Otherwise, simply examining the relationship between hemoglobin level and sepsis outcome may ignore the impact of hemoglobin dynamic changes on the outcome. Some studies have shown that the hemoglobin trajectory subgroups are related to the occurrence of acute kidney injury [9,10] , and the uid balance trajectory is also related to sepsis mortality [11] . However, studies on trends of Hb in sepsis patients have not been evaluated.…”