Shrunken pore syndrome increased the risk of acute kidney injury after cardiac surgery: a cohort study

Background Shrunken pore syndrome (SPS), as a selective glomerular hypofiltration syndrome, has received increasing attention. Therefore, we hypothesised that patients with SPS have a high risk of postoperative acute kidney injury (AKI).Methods This trial was a retrospective cohort study. Patients who received isolated coronary artery bypass grafting (CABG) in the Affiliated Hospital of Qingdao University were continuously reviewed. Estimated glomerular filtration rates (eGFRs) were calculated by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. The SPS was defined as an eGFR based on cystatin C < 70% of the eGFR based on creatinine. Postoperative AKI was diagnosed according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria, and the occurrence of AKI within seven days after surgery was followed up.Results A total of 1277 patients were included, and the incidence of postoperative AKI was 23.2% (296/1277), and 12.8% (164/1277) patients were diagnosed with SPS before surgery. The incidence of AKI in the SPS group was significantly higher than that in the non-SPS group (33.5% vs. 21.7%, adjOR = 1.613, 95%CI 1.121–2.322, p = 0.010). Sensitivity analysis: E-value = 2.175 and Fragility Index = 8. The results remained robust across all subgroups. After propensity score matching, the incidence of AKI in SPS group was still significantly higher than that in the non-SPS group (33.5% vs. 22.9%, adjOR = 1.702, 95%CI 1.131–2.560, p = 0.011).Conclusions SPS is an independent risk factor for AKI after CABG. It will bring a new insight for an accurate clinical assessment of the risk of postoperative AKI.