Impact of chronic kidney disease on clinical outcomes after cardiac surgery

Background Chronic kidney disease (CKD) is common in patients requiring cardiac surgery. The objective of this work was to study the impact of CKD on clinical outcomes after cardiac surgery and to compare outcomes in patients with different grades of renal functions. We retrospectively reviewed all patients who underwent cardiac surgery from January 2018 to January 2023 at our tertiary care hospital Methods Chronic kidney disease was defined as glomerular filtration rate (GFR) < 60 ml/min/1.73 m2 for ≥ 3 months regardless of the etiology . Clinically, the CKD was classified into early CKD with GFR 30-60 ml/min/1.73 m2, late CKD with GFR <30 ml/min/1.73 m2, and end-stage renal disease (ESRD) on hemodialysis. The primary outcome was hospital mortality. Results Our cohort included 1334 adult patients, of them 227 (17%) had CKD. 160(12%) patients had early CKD, 21(1.6%) patients had late CKD, and 48(3.6%) patients had ESRD on hemodialysis. The patients with CKD had greater hospital mortality (15.4% vs. 6.6%, p<0.001), acute kidney injury (52.4% vs. 18.1%, p<0.001), new need for dialysis (33.5% vs. 7.9%, p<0.001) and longer ICU stay [8(3,26) vs. 3(2,7) days, p<0.001] than those without pre-operative CKD. There were insignificant differences regarding cerebrovascular stroke and deep wound infection. Cox-proportional hazard analysis revealed that pre-operative CKD increased the risk of postoperative mortality with an adjusted Hazard Ration (HR) 2.88 (95%CI:1.87-4.422, p<0.001). Kaplan-Meier curves showed the decreased survival with pre-operative CKD and the patients with late CKD had the lowest survival (log-rank p<0.001). Conclusions The patients with CKD had worse postoperative outcomes compared to non-CKD patients after cardiac surgery. Patients with dialysis-independent CKD had increased risks of needing dialysis, hospital mortality, and permanent dialysis after cardiac surgery.Kaplan-Meier curves of the study groups.