Is there a volume-outcome relationship for partial nephrectomy?

OBJECTIVE: To investigate the impact of hospital volume on partial nephrectomy indications and outcomes. MATERIALS AND METHODS: Data were extracted from the National Observational Registry on the Practice and Hemostasis in Partial Nephrectomy registry. Four groups were created according to the number of partial nephrectomy (PN) performed: very high (VH, ≥ 19 PN), high (H, 10-18 PN), moderate (M, 4-9 PN) and low (L, <4 PN) PN activity. Indications and surgical outcomes were compared among all groups. The effect of hospital volume on postoperative complications and positive margin rate was examined by a multivariable analysis. RESULTS: Fifty-three centers included a total of 570 PN. There were 9 VH, 13 H, 12 M and 19 L volume centers which performed 270 (47.4 %), 179 (31.4 %), 74 (13 %) and 47 (8.2 %) PN, respectively. Patients in higher volume centers were significantly younger (p = 0.008), had a lower BMI (p = 0.002) and decreased ASA score (p < 0.001). PN was more frequently performed in higher volume centers (p = 0.006) particularly in case of renal masses <4 cm (p = 0.005). Open surgery was the most common approach in all groups, but laparoscopic PN was more frequent in M volume hospitals (p < 0.001). Positive margin (p = 0.06) and complications (p = 0.022) rates were higher in M group. In multivariable analysis, renal chronic disease was an independent predictor of positive margin rate (p < 0.001, OR 3.91). CONCLUSIONS: PN is more frequently performed in high volume institutions particularly for small renal masses. We observed increase positive margin and complication rates in moderate volume centers that might be explained by an increased use of laparoscopy.