Multicenter Randomized Controlled Trial Comparing Pulse-Modulated Holmium:YAG Laser and Thulium Fiber Laser in Retrograde Intrarenal Surgery for Dusting Kidney Stones

PURPOSE: High-power lasers have revolutionized the treatment of stones during retrograde intrarenal surgery, but single center and retrospective studies comparing stone-free rates and efficiency of the two most commonly used modalities, pulse modulated Holmium:YAG and Thulium Fiber Laser, have had conflicting results. We designed a multicenter randomized controlled trial to address these discrepancies. MATERIALS AND METHODS: After IRB approval, 5 U.S. centers recruited and prospectively randomized adults aged 18-89 with intrarenal stones ≥5 mm to ≤20 mm to receive retrograde intrarenal surgery with a Holmium:YAG or Thulium Fiber Laser with the goal to dust all stones. The primary outcome was stone free rates on computed tomography at 6-12 weeks. Secondary outcomes included procedure time, laser efficiency parameters, and complications. RESULTS: Demographics and pre-operative stone parameters of the 178 enrolled patients were similar between treatment arms. Zero fragment stone free rates were 36/68 (52.9%) for Holmium:YAG and 34/65 (52.3%) for Thulium Fiber Laser and were nearly identical (p=0.942). Procedure time, laser time, laser efficiency, and complication rates also did not show any statistical difference between groups. CONCLUSIONS: This multi-center randomized controlled trial found no statistically significant difference in stone free rate, complications, or efficiency between high-power pulse-modulated Holmium:YAG and Thulium Fiber Laser. They are both effective at treating intrarenal stones ≤ 2 cm. Surgeon and institutional preferences can dictate which laser to use.