To analyze the influence of preoperative renal function on postoperative renal outcomes after radical nephrectomy (RN) and nephron-sparing surgery (NSS) for malignancy in patients stratified according to preoperative chronic kidney disease (CKD) stage and surgical extent (NSS vs RN).

Retrospective review of patients undergoing renal surgery for localized renal masses stratified by surgical extent and preoperative CKD stage based on glomerular filtration rate (GFR) level: stage I (>90 mL/min/1.73 m²), stage II (60-89 mL/min/1.73 m²), and stage III (30-59 mL/min/1.73 m²). Survival analysis for significant renal impairment was based on freedom from the development of new-onset GFR <30 or <45 mL/min/1.73 m².

A total of 1306 patients were included in the analysis with preoperative CKD stage I (27.9%), II (52.1%), and III (20.1%); 41.3% and 58.7% underwent NSS and RN, respectively. NSS was associated with a lower annual rate of GFR decline in preoperative CKD stage-I (P = .028) and stage-II patients (P = .018), but not in CKD stage-III patients (P = .753). Overall, 5.0% and 15.0% developed new-onset GFR <30 mL/min/1.73 m² and <45 mL/min/1.73 m², respectively. There was no difference in the probability of developing significant renal impairment between NSS and RN in CKD stage-I or -III patients, whereas only in CKD stage-II patients was the surgical extent independently associated with development of significant renal impairment (RN: odds ratio, 9.0; P = .042 for GFR <30 mL/min/1.73 m² and odds ratio, 2.3; P = .003 for GFR <45 mL/min/1.73 m²).

Compared with RN, NSS is associated with a lower rate of GFR decline for preoperative CKD stage-I and -II patients, but only CKD stage-II patients demonstrated a decreased risk of developing significant renal impairment.