EAU 2018: The Learning Curve for Robot-Assisted Partial Nephrectomy: Impact of Surgical Experience on Perioperative Outcomes

Copenhagen, Denmark (UroToday.com) Robot-assisted partial nephrectomy [RAPN] is a complex procedure and surgical outcomes are affected by increasing experience. The aim of the study was to investigate the effect of surgical experience [EXP] on perioperative outcomes, and to define the surgical learning curve for RAPN, since actual curves are rarely presented.

A total of 457 patients treated with RAPN for a cT1-2 renal mass by two surgeons with extensive EXP (>300 cases) were assessed from a prospective database. For each patient, EXP was defined as the total number of RAPN performed by each surgeon before the patient's operation. Outcomes of the study were warm ischemia time [WIT], Clavien-Dindo ≥2 postoperative complications [CD≥2], and positive surgical margins [PSM]. Multivariable linear (WIT) and logistic regression (CD≥2, PSM) models tested the effect of EXP on the outcomes. Restricted cubic splines were used to test for the non-linear nature of the relationship between EXP and the outcomes. Covariates consisted of tumour preoperative size and RENAL nephrometry score to account for case mix. Model-derived coefficients were used to calculate estimated WIT and probability of CD≥2-free postoperative course. Local polynomial smoothing method was used to depict actual curves.

Median EXP was 148 cases (interquartile range [IQR] 65-254). Median WIT was 14 min (IQR 10-19). The rate of CD≥2 and PSM were 14% and 4%, respectively. Increasing EXP was associated with lower ischemia time (1st spline estimate -4.5 minutes per 25 cases; 95% confidence intervals [CI] -2.3, -1.3; p<0.0001) and with higher probability of CD≥2-free postoperative course (OR 1.01 per 25 cases; CI:1.005,1.02; p<0.001). Conversely, EXP was not associated with PSM (OR 1.00; CI 0.99,1.002; p=0.5). The relationship between EXP and WIT was non-linear, with a steep reduction in WIT from case 1 to case 100 and a plateau observed after 150 cases (Figure 1 panel A). Conversely, the relationship between EXP and CD≥2 resulted in a linear curve, without a plateau being observed even after 300 cases (Figure 1 panel B). 

Perioperative outcomes after RAPN are affected by surgical experience. After 150 RAPNs, no further improvement is observed with respect to WIT. Conversely, when CD≥2 are taken into considerations, the learning curve does not appear to end, without a plateau even after 300 cases.

Larcher 1

Presented by: Larcher A, MD ORSI Academy, Dept. of Urology, Melle, Belgium

Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, twitter: @GoldbergHanan at the 2018 European Association of Urology Meeting EAU18, 16-20 March, 2018 Copenhagen, Denmark