Relationship Between Clinical Factors and the Occurrence of Post-Operative Acute Kidney Injury in Patients Undergoing Nephron-Sparing Surgery

Abstract

Nephron-sparing surgery (NSS) is a very common urological procedure performed for clinically localized renal tumors. Compared to radical nephrectomy, it is associated with better renal function preservation and has similar oncologic safety, but with higher complications rate. One of the most important complications is the occurrence of post-operative acute kidney injury (AKI), which has the potential to affect long-term renal function. To study the clinical factors that affect post-NSS renal function and put the patients at risk for AKI. From our NSS cohort, we analyzed the clinical and surgical data of 464 patients who were divided into AKI and non-AKI group. Patients with solitary kidney were excluded. Renal function was assessed using serum Creatinine (sCr) and estimated glomerular filtration rate (eGFR) that was evaluated using the MDRD equation. SCr was assessed daily starting one day before surgery and until the patient was discharged (usually on post-operative day 3). AKI was defined using AKIN and RIFLE criteria. Appropriate statistical analyses were undertaken to compare between the different groups. Of 464 patients, 183 (39.4%) developed AKI following surgery. The AKI patients were more likely to be of male gender (72% vs 58%, p = 0.003), and suffered more from cardiovascular diseases, including hypertension (66.1% vs 52.6%, p = 0.007), ischemic heart disease (24.6% vs 16.3%, p = 0.04) and diabetes mellitus (20.7% vs 13.8%, p = 0.04). Statistically significant differences between the groups in surgical parameters included longer average ischemia time (26 min vs 23.3 min, p = 0.004), higher mean blood loss (153 mL vs 85 mL, p = 0.01), higher transfusion rate (7.1% vs 2.1%, p = 0.01) and the use of tissue adhesive rather than conventional sutures for tumor bed closure, which had a protective effect from AKI. Multivariate analysis showed longer ischemia time, baseline chronic kidney disease and male gender to be the most important and independent risk factors for developing AKI. The most important predictors of AKI are ischemia time, baseline chronic kidney disease and male gender. Of these factors, ischemia time is the only modifiable factor, and hence should be kept to the shortest time possible.