Does the rate of shock wave delivery affect outcomes in patients receiving shock wave lithotripsy for urinary calculi?

This Practice Point discusses a meta-analysis performed by Semins and colleagues, which included a total of 589 patients from four studies who were randomized to receive shock wave lithotripsy (SWL) delivered at either 120 shock waves per minute (fast rate) or 60 shock waves per minute (slow rate). The slow-rate group had a 10.2% increased chance of successful treatment compared with the fast-rate group (P=0.002). Whilst this paper adds to existing evidence suggesting improved outcomes for slow-rate versus fast-rate SWL, the small sample size and heterogeneity of the studies included make it difficult to draw definitive conclusions. Varying the shock wave delivery rate according to patient, lithotripter system and stone characteristics, might form an important part of individualizing SWL treatment protocols. The potential advantages of slow-rate SWL must be weighed against the disadvantages of increased treatment times. Large multicenter studies will be required to determine how best to tailor SWL treatment to the individual patient.