Comparison of shockwave frequencies of 30 and 60 shocks per minute for kidney stones: a prospective randomized study

Objective: One of the factors that determines the treatment success of shockwave lithotripsy (SWL) is the frequency of the shockwaves during the procedure. This study compared the efficacy and pain perception of shockwave frequencies at 30 versus 60 shocks/min for kidney stones. Materials and methods: From August 2013 to May 2015, 160 patients with solitary, radiopaque kidney stones were randomized to SWL at 30 shocks/min (group 1) or 60 shocks/min (group 2), with 80 patients in each group. The primary outcome measure was success rate at 3 months after the last SWL session. The secondary outcome measure was pain perception during the procedures. Results: Of the 160 randomized patients, data for a total of 148 patients (74 patients in group 1 and 74 patients in group 2) were analyzed, after the exclusion of the patients lost to follow-up or who required secondary intervention within 3 months. There was no statistically significant difference between the two groups in terms of the success rate at 3 months (68.9% vs 71.6%, p = .719). However, the mean visual analogue scale scores of all the sessions were significantly higher in group 1 than in group 2 (5.83 vs 4.06, p <. 05). Stone location, especially the lower calyceal location, was the only significant negative predictor for success according to multivariate logistic regression analysis. Conclusions: The success rate was similar between these two frequencies. However, pain perception was significantly higher at 30 than at 60 shocks/min.