Prognostic value of supar and hs-crp on acute kidney injury following on-pump cardiac surgery

Introduction Acute kidney injury (AKI) is a serious complication after cardio-pulmonary bypass (CPB) surgery, occurring in approximately 20-30% of all patients1. Elevated preoperative levels of the proinflammatory biomarkers soluble urokinase-type plasminogen activating receptor (suPAR) and high-sensitivity C-Reactive Protein (hs-CRP) have previously been associated with occurrence of AKI in selected cardiac surgery populations. Aim of this study was to investigate the relation between suPAR and hs-CRP-concentrations and occurrence of AKI in unselected cardiac surgery patients. Methods Adult patients admitted for elective on-pump cardiac surgery, from August 2012 to June 2018, were included (n=924). Preoperative biobank blood samples were retrospectively analysed for suPAR and hs-CRP levels. We assessed the relationship between suPAR/hs-CRP-values and AKI (any stage), defined by the KDIGO (Kidney Disease: Improving Global Outcomes) criteria, using adjusted logistic regression with both biomarkers evaluated either as a continuous variables (log2-transformed) or as quartiles, with the lowest quartile serving as reference. Further, we performed adjusted logistic regression with the biomarkers as continuous variables (log2-transformed), to assess the following secondary outcomes: KDIGO 1, KDIGO 2-3, and need for renal replacement therapy (RRT). Results AKI (any stage) within 7 days was observed in 327 patients (35.4%) and 26 patients (2.8%) required RRT during hospitalisation. Severity of AKI was 265 (28.7%), 33 (3.6%) and 29 patients (3.1%), for KDIGO stage 1, 2 and 3, respectively. A doubling of suPAR and hs-CRP corresponded to an odds ratio (OR) for AKI of 1.62 (95% CI 1.26-2.09, p 3.42 ng/mL) and 29% in the lowest quartile ( Discussion Elevated preoperative levels of suPAR were associated with increased risk for AKI development evaluated by multiple AKI outcomes. Conversely, increasing hs-CRP-levels were not associated with AKI development. Preoperative assessment of suPAR-concentration may provide prognostic information for AKI development in patients undergoing elective on pump cardiac surgery.