Supplementary Material for: Protein kinase N1 level predicts acute kidney injury in patients undergoing cardiac surgery：A prospective cohort study

Introduction: The objective of this study is to examine the utility of protein kinase N1 (PKN1) as a biomarker of cardiac surgery-associated AKI (CSA-AKI).
Methods: A prospective cohort study of 110 adults undergoing on–pump cardiac surgery was conducted. The associations between post-operative PKN1 and CSA-AKI, AKI severity, need for renal replacement therapy (RRT), duration of AKI, length of ICU stay and post-operative hospital stay were evaluated.
Results: Patients were categorized into three groups according to PKN1 tertiles. The incidence of CSA-AKI in the third tertile was 3.4-fold higher than that in the first. PKN1 was an independent risk factor for CSA-AKI. The discrimination of PKN1 to CSA-AKI assessed by ROC curve indicated that the AUC was 0.70, and the best cutoff was 5.025ng/mL. This group (>5.025ng/mL) was more likely to develop CSA-AKI (P<0.001). The combined AUC of EuroSCORE, aortic cross-clamp time and PKN1 was 0.82 (P<0.001). A higher level of PKN1 related to increased need for RRT, longer duration of AKI, and length of ICU and post-operative hospital stays.
Conclusions: PKN1 could be a potential biomarker for the prediction of CSA-AKI. The combination of PKN1, EuroSCORE and aortic cross-clamp time were likely to predict the occurrence of CSA-AKI.