MP44-18: Prolonged endourological training is the key to improve surgical outcomes of stone patients treated with flexible ureteroscopy.

Luca Villa*, Pietro Dioni, Margherita Fantin, Mario de Angelis, Christian Corsini, Milan, Italy, Olivier Traxer, Paris, France, Alberto Briganti, Francesco Montorsi, Eugenio Ventimiglia, Andrea Salonia, Milan, Italy

Introduction: We sought to evaluate the impact of a one-year clinical fellowship on the surgical outcomes of flexible ureteroscopy (URS) achieved at a tertiary care referral center.

Methods: We identified 307 patients treated with URS for ureteral/renal stones from January 2015 to June 2021 at a single center. All the procedures have been performed by experienced surgeons (more than 50 procedures/each). Of those, two of them had a one-year clinical fellowship at a stone referral center (Tenon Hospital, Paris, France). Optimal surgical outcome (OSO) was defined as the absence of residual fragments (stone free rate, SFR) or the presence of fragments <=3mm at 1-month postoperative imaging (US, US+KUB or CT scan). We divided patients in two groups: a) patients treated by the two trained surgeons; and, b) patients treated by 5 other experienced surgeons. Descriptive statistics explored patients’ characteristics and compared OSO of the two groups of patients. Uni- and multivariate logistic regression analyses (UVA and MVA) tested the impact of stone characteristics, surgical data (pre-stenting, operative time, the use of ureteral access sheath), surgeon’s experience and imaging technique on the rate of SFR. Sub-analyses were made dividing patients according to the stone size (<=13 mm vs. >13 mm).

Results: Median (IQR) stone size was 13 mm (8-15). Of 307 patients, 211 (68.7%) were operated by the 2 trained surgeons. The overall OSO was 61.6%. OSO was achieved in 137 (65.6%) and 50 (52%) of patients treated by prolonged trained and regular trained surgeons, respectively (p=0.02). At UVA, prolonged training (OR=1.75;95%CI=1.07-2.86), stone diameter (OR=0.92;95%CI=0.88-0.96), stone location (kidney vs. ureter; 0.35;0.21-0.58), imaging technique (TC vs. US/US+KUB, OR=0.27;95%CI=0.16-0.47) predicted OSO achievement (all p<0.03). At MVA analyses, prolonged training was associated with OSO (OR=2.22;95%CI=1.29-3.82; p<0.01), along with the others aforementioned variables. The effect of training resulted more evident in patients with large stone (> 13 mm), with a 4.78-fold likelihood of achieving OSO compared to patients treated by non-trained surgeons (95%CI=1.26-18.15;p=0.02).

Conclusions: One-year clinical fellowship in a stone treatment referral center effectively affects surgeon performances, especially in patients with a high stone burden, with an almost 5-fold high rate of OSO achievement compared to surgeons supposed to have already completed their learning curve.

Source of Funding: none