Long-term chronological changes in renal function and functional renal volume after nephron-sparing surgery: A prospective observational study.

OBJECTIVES To investigate long-term chronological changes in functional renal volume and renal function after nephron-sparing surgery, and factors that contribute to the progression of postoperative chronic kidney disease. METHODS A total of 80 patients who underwent nephron-sparing surgery were enrolled in this prospective observational study. The renal function deterioration group was defined as patients whose estimated glomerular filtration rate at 5 postoperative years decreased by ≥20% relative to that before surgery. RESULTS The predicted estimated glomerular filtration rate, calculated based on the functional renal volume at 5 postoperative years, was strongly correlated with the postoperative estimated glomerular filtration rate (Spearman's ρ = 0.89, P < 0.001). The rate of new-onset stage IIIb chronic kidney disease was significantly higher in the renal function deterioration group than in the stable renal function group (P < 0.001). Multivariate analysis identified proteinuria (P = 0.017), small preoperative total functional renal volume (≤250 mL, P = 0.046) and large tumor volume (≥4.5 mL, P = 0.036) as independent factors associated with renal function deterioration. CONCLUSIONS Our findings show that the functional renal volume is significantly associated with renal function, even in the long-term postoperative period. Additionally, for patients with preoperative proteinuria, large tumor volume and small total preoperative functional renal volume, both oncological follow ups and medical interventions, including prevention of lifestyle-related diseases, might prevent the progression of chronic kidney disease.