PD19-01: Randomized Controlled Trial (RCT) Comparing Holmium Laser with Moses Technology and SuperPulsed Laser System with Thulium Laser for Renal and Ureteral Stones: Preliminary Single Center Results

Christopher Haas*, Margaret Knoedler, Shuang Li, Kristina L. Pennniston, Sara Best, Stephen Y. Nakada, Madison, WI

Introduction: The primary objective of this study is to compare the laser efficiency between the 2 dominant but different modalities for ureteroscopic stone management: the Holmium Laser with Moses Technology and the Thulium Laser.  Primary outcome was ureteroscope time (time from ureteroscope entering to leaving the ureter) required to adequately fragment stones to 1mm or less. Secondary outcomes were laser efficiency as measured by the ratio of stone volume to laser activation time, stone-free rate, and complication rate.

Methods: An IRB approved randomized clinical trial was conducted to randomize patients to outpatient treatment with either the Moses or Thulium laser in a 1:1 manner after stratification into groups based on the maximal diameter of treated stone (3-9.9 mm or 10-20 mm).  Sample size requirements to achieve an 80% power to detect a 3-minute difference within subgroups was 164 subjects. Patient, stone, and operative parameters were collected and compared using the appropriate categorical/continuous and parametric/nonparametric statistical tests (SPSS 25).

Results: From 7/16/21 to 10/29/21, 58 patients have completed the protocol; 29 patients were randomized to Moses and 29 patients to Thulium.  There were no significant differences between groups for baseline patient demographics nor pre-operative characteristics, including the proportion of patients with a ureteral stent in-situ (Moses 24.1% vs Thulium 41.4%, p = 0.162), ureteral vs. renal stones (55% vs 31%, p = 0.07), mean number of stones treated (1.4 vs 1.8, p = 0.19), median maximal stone diameter size (7.8 vs 9.0, p = 0.70), mean cumulative stone volume (223 vs 219mm3, p = 0.91), and median stone Hounsfield units (1071 vs 977, p = 0.205).  Laser settings were comparable between Moses and Thulium with fragmentation set to 0.8 J and 8 Hz and dusting settings at 0.3 J and 80 Hz.   Ureteroscope time was not significantly different between modalities (median Moses time 20m vs Thulium 18m, p = 0.73) nor was laser efficiency as measured by stone volume/laser activation time (mean 67mm3/min vs 52mm3/min, p = 0.20).

Conclusions: Preliminary results from this important RCT suggest no significant advantage of one technology over the other.  Both are highly effective and safe, and thus surgeon and institutional preference is the best approach when selecting one or the other. Further enrollment, subgroup analyses and long-term outcomes will be important.

Source of Funding: none