Pulse-modulated Holmium:YAG Laser vs the Thulium Fiber Laser for Renal and Ureteral Stones: A Single-center Prospective Randomized Clinical Trial

Purpose: We sought to compare the clinical effectiveness of the pulse-modulated Ho:YAG (holmium:yttrium-aluminum-garnet) laser and the thulium laser fiber for ureteroscopic stone management in a randomized clinical trial. The primary outcome was the ureteroscope time required to adequately fragment stones to 1 mm or less. Secondary outcomes were stone-free rate, complications, subjective surgeon measurement of laser performance, patient related stone quality of life outcomes, and measurements of laser efficiency. Materials and Methods: An Institutional Review Board-approved randomized clinical trial was conducted to randomize patients to outpatient treatment with either the Moses 2.0 or thulium laser fiber 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). Patient, stone, and operative parameters were compared using the appropriate categorical/continuous and parametric/nonparametric statistical tests (SPSS 25). Results: From July 16, 2021 to March 11, 2022, 108 patients were randomized and had primary endpoint data available for analysis; 52 patients were randomized to Ho:YAG and 56 patients to thulium laser fiber. Groups were well balanced with no significant differences observed for patient or stone characteristics. Ureteroscope time was not significantly different between modalities (Ho:YAG mean 21.4 minutes vs thulium laser fiber mean 19.9 minutes, P= .60), or within subgroup analysis by stone size, median Hounsfield units, or stone location. There were no significant differences observed in the stone-free rate and complications rate between the 2 lasers. Conclusions: This randomized clinical trial suggests no significant clinical advantage of one laser technology over the other. Surgeon and institutional preference are the best approach when selecting one or the other.