title: A randomized, double-blind trial to compare shock wave frequencies of 60 and 120 shocks per minute for upper ureteral stones.
abstract: OBJECTIVE
  Recent evidence demonstrates that decreasing shock wave frequency from the previous standard of 120 to 60 shocks per minute results in improved fragmentation of stones located within the renal collecting system. We report the first randomized trial to our knowledge to examine the effect of a slower shock wave frequency for shock wave lithotripsy on stones located in the proximal ureter.
  
  
  METHODS
  A total of 163 patients with a previously untreated radiopaque calculus in the upper ureter measuring at least 5 mm underwent stratified block randomization according to stone size, and shock wave lithotripsy at 60 or 120 shocks per minute. Stone-free status at 3 months was confirmed with noncontrast computerized tomography or a plain abdominal x-ray and ultrasound study.
  
  
  RESULTS
  Of the patients 77 were randomized to 60 shocks per minute and 86 were randomized to 120 shocks per minute. The groups were similar in gender, age, body mass index and initial stone area. At 3 months the 60 shocks per minute group had a higher overall stone-free rate (64.9% vs 48.8%, p = 0.039). Significantly fewer shocks were administered to patients treated at 60 shocks per minute (mean 2,680 vs 2,940, p <0.001). However, mean treatment times were longer (44.3 vs 24.5 minutes, p <0.001). Patients treated with 60 shocks per minute required fewer auxiliary procedures (29.9% vs 45.4%) (p = 0.031).
  
  
  CONCLUSIONS
  Decreasing the rate of shock wave administration from 120 to 60 shocks per minute results in improved stone-free rates. A slower treatment rate of proximal ureteral stones reduces the need for additional shock wave lithotripsy or more invasive treatments to render patients stone-free, without any increase in morbidity, and with an acceptable increase in treatment time.
authors.affiliation: Division of Urology, Department of Surgery, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: R J D'A
authors.initials: RJ
authors.lastname: Honey
authors.forename: T D
authors.initials: TD
authors.lastname: Schuler
authors.forename: D
authors.initials: D
authors.lastname: Ghiculete
authors.forename: K T
authors.initials: KT
authors.lastname: Pace
mesh_terms: D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014514:Ureteral Calculi / Q000473:pathology / Q000628:therapy*