Optimization of Extracorporeal Shock Wave Lithotripsy Delivery Rates Achieves Excellent Outcomes for Ureteral Stones: Results of a Prospective Randomized Trial

Purpose: Management of ureteral stones remains controversial. To determine whether optimizing the extracorporeal shock wave lithotripsy delivery rate would improve the treatment of solitary ureteral stones we compared the outcomes of 2 delivery rates in a prospective randomized trial.

Materials and methods: From July 2010 to October 2012, 254 consecutive patients were randomized to extracorporeal shock wave lithotripsy at a shock wave delivery rate of 60 and 90 pulses per minute in 130 and 124, respectively. The primary study end point was the stone-free rate at 3-month followup. Secondary end points were stone disintegration, treatment time, complications and the rate of secondary treatments. Descriptive statistics were used to compare end points between the 2 groups. The adjusted OR and 95% CI were calculated to assess predictors of success.

Results: The stone-free rate at 3 months was significantly higher in patients who underwent extracorporeal shock wave lithotripsy at a shock wave delivery rate of 90 pulses per minute than in those who received 60 pulses per minute (91% vs 80%, p = 0.01). Patients with proximal (100% vs 83%, p = 0.005) and mid ureteral stones (96% vs 73%, p = 0.03) accounted for the observed difference but not those with distal ureteral stones (81% vs 80%, p = 0.9, respectively). Treatment time, complications and the rate of secondary treatments were comparable between the 2 groups. On multivariable analysis the shock wave delivery rate of 90 pulses per minute, proximal stone location, stone density, stone size and an absent indwelling Double-J® stent were independent predictors of success.

Conclusions: Optimizing the extracorporeal shock wave lithotripsy delivery rate can achieve excellent results for ureteral stones.