Comparing Thulium Fiber Versus High-Power Holmium Laser Lithotripsy Combined with the Flexible and Navigable Suction Access Sheath in Flexible Ureteroscopy for Kidney Stone Disease: A Propensity Score Matched Analysis by the Global FANS Collaborative Group.

Objective: We aim to evaluate stone-free rate (SFR) and complications after flexible ureteroscopy (F-URS) for kidney stones, using a flexible and navigable suction ureteral access sheath (FANS), comparing thulium fiber laser (TFL) and high-power holmium:yttrium-aluminum-garnet laser (HPHL). Methods: Data from adults who underwent F-URS in 15 centers were prospectively analyzed (August 2023-January 2024). Exclusion criteria were ureteral stones, concomitant bilateral procedures, and renal abnormalities. One-to-one propensity score matching for age, gender, stone location, stone volume, and Hounsfield unit was performed. SFR was assessed using computed tomography scan within 30 days and defined as zero fragments. Data are presented as median (25th-75th quartiles). Multivariable logistic regression was performed to evaluate predictors of SFR. Results: Of included patients, HPHL was used in 114 patients and TFL in 181 patients. After matching, 96 patients from each group with similar baseline characteristics were included. There was no difference between the groups regarding the use of disposable scopes, lithotripsy mode, and ureteroscopy, lasing and total surgical time. There was no case of sepsis, and blood transfusion was necessary for only one patient in the HPHL group. The incidence of transient fever was similar (3.4% in HPHL vs 3.8% in TFL group). Postoperative day 1 loin pain did not differ significantly. Postoperative stay did not differ significantly [1 [0, 2] in HPHL vs 1 [0, 1] days in TFL group, p = 0.12]. Thirty-day SFR was similar (52.1% for HL vs 64.6% for TFL group, p = 0.11). At multivariable analysis, the use of TFL (odds ratio 1.95, 95% confidence interval 1.01-3.82) was significantly associated with higher odds of being stone-free. Conclusions: Both lasers are safe and efficacious and can be suitably used for F-URS with FANS with high SFR and minimal complications.