[Partial nephrectomy on solitary kidney: Renal function outcome and predictive factors of impairment]

Objectives: To assess the postoperative functional outcome of PN in solitary kidney and define some predictive factors of renal change.

Material and methods: A monocentric series of 45 partial nephrectomies on solitary kidneys, performed between 1988 and 2014, was retrospectively analyzed. Pre-, per- and postoperative clinicopathological data were collected in the UroCCR database. The evolution of early, medium and long-term postoperative Glomerular Filtration Rate (GFR) was evaluated. Predictive factors of GFR decline and hemodialysis were assessed in multivariate analysis.

Results: Mean age was 61 years old (±10.8). Mean preoperative GFR and tumor size were respectively 59.6 mL/min (±18.7) and 3.9 cm (±2.6). Vascular clamping was performed in 41 cases (91%). Median time of warm ischemia was 20 minutes (2-60). Mean follow-up was 66 months (±47). Mean GFR at day 5, 1 month and last follow-up were respectively 46.4 mL/min, 50.3 mL/min and 53.1 mL/min. At day 5 and at last follow-up, a GFR decrease ≥ 20% was found in 20 patients (44.4%) and in 16 patients (35.5%), respectively. Five patients (11%) required definitive hemodialysis (HD) at last follow-up. At day 5, tumor size>4 cm (0.006) and operative time (P=0.003) were independent predictive factors of GFR decline. At 1 year, RENAL ns ≥ 10 was the only independent predictive factor of GFR alteration (P=0.0007). Preoperative GFR was significantly associated with final hemodialysis (P=0.023).

Conclusion: Partial nephrectomy allows most of the patients presenting with renal cell carcinoma on solitary kidney to be free of hemodialysis. Tumor complexity, tumor size and preoperative GFR seems to play a determinant role on postoperative functional outcome. These non-modifiable predictive factors should be recognized and taken into account to better select patients with high risk of postoperative renal failure.

Level of evidence: 5.