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

Robot-assisted partial nephrectomy (RAPN) outcomes might be importantly affected by increasing surgical experience (EXP). The aim of the study is to investigate the effect of EXP on warm ischemia time (WIT), presence of at least one Clavien-Dindo ≥2 postoperative complication (CD ≥ 2), and positive surgical margins (PSMs) to define the learning curve for RAPN. We evaluated 457 consecutive patients diagnosed with a cT1-T2 renal mass were evaluated. EXP was defined as the total number of RAPNs performed by each surgeon before each patient's operation. Median WIT was 14min and the rate of CD ≥ 2 and PSMs was 15% and 4%, respectively. At multivariable regression analyses adjusted for case mix, EXP resulted associated with shorter WIT (p<0.0001) and higher probability of CD ≥ 2-free postoperative course (p=0.001), but not with PSMs (p=0.7). The relationship between EXP and WIT emerged as nonlinear, with a steep slope reduction within the first 100 cases and a plateau observed after 150 cases. Conversely, the relationship between EXP and CD ≥ 2-free course resulted linear, without reaching a plateau, even after 300 cases. Patient summary: Perioperative outcomes after robot-assisted partial nephrectomy (RAPN) are importantly and individually affected by surgeon's experience. After 150 RAPNs, no further improvement is observed with respect to ischemia time, but the learning curve appears endless with respect to complications.