When Prof. Christian Chaussy and associates ¹ reported stone fragmentation using shockwaves in the 1980s, the management of upper tract urolithiasis was revolutionized. Thirty years later, shockwave lithotripsy (SWL) using third- and fourth-generation lithotripters remains one of the important minimally invasive management options in the treatment of patients with urolithiasis, and it is associated with high stone-free rates. ^2,3 Yet over the last 20 years, miniaturization of flexible ureteroscopes and widespread use of the holmium laser as an energy source for lithotripsy have led to safe and successful management of proximal ureteral stones and renal stones with ureteroscopy (URS) and laser lithotripsy.

Based on the high stone-free rates achievable with URS, the 2007 American Urological Association/European Association of Urology guidelines recommended both SWL and URS as first-line management options for all ureteral stones including the proximal ureteral stones. ⁴ Although URS enjoyed slightly higher stone-free rates, it was also associated with slightly higher risk of ureteral complications when compared with SWL. ⁴ Similarly, a randomized clinical trial comparing SWL with URS for <1 cm lower pole renal stones showed that both procedures resulted in similar stone-free rates, while SWL was associated with greater patient acceptance and shorter convalescence. ⁵

In addition, evidence suggests that ureteral injury may be found in up to 46.5% of patients undergoing URS with ureteral access sheath. ⁶ Moreover, URS has been shown, at least in the United Kingdom, to be more expensive than SWL. ⁷

Yet it seems that there has been a gradual decrease in the use of SWL as a treatment modality in the management of urolithiasis leading some to believe that SWL is on the verge of extinction. For example, a study from the province of Ontario, Canada, has demonstrated that over the period from 1991 to 2010, there was a significant decrease in the use of SWL (69%–34%; P < 0.0001), which was made up by a significant increase in the use of URS (25%–59%; P < 0.0001) (Fig. 1). ⁸ However, this may not be representative of global trends in the use of SWL vs URS for management of upper tract urolithiasis. Therefore, a global prospective study on SWL is urgently needed. What a better forum than to have the Clinical Research Office of the Endourological Society (CROES) to spearhead such a global initiative. After all, the CROES has a track record of publishing the largest prospective global series on both PCNL and URS. ^9,10

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FIG. 1.

Population-based study demonstrating percent treatment utilization of shockwave lithotripsy (SWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PCNL) in the management of kidney stones in the province of Ontario, Canada. Adapted from Ordon et al., J Urol, 2014. ⁸

What are the important variables that could be collected? Although these variables could be later refined by the Steering Committee, here are some important variables to include in the database. In terms of preoperative evaluation, these variables would be collected: Age of patients (any children?), comorbidities, continuation of nonsteroidal anti-inflammatory agents at time of SWL, CT variables (skin-to-stone distance, Hounsfield units, stone size, location), and requirements for preoperative urine culture and electrocardiography. In terms of intraoperative factors, it is important to include: The type of lithotripter, narrow vs wide focus, dose escalation, maximum energy level, shock rate (1 Hz vs 2 Hz), gating, pre-SWL ureteral stent placement, type of anesthesia, prophylactic antibiotics, operative and fluoroscopy times, and the number of radiological technologists and urologists per center. Postoperative factors include: Fragmentation rate, stone-free rates at 1 and 3 months, clinically significant perirenal hematomas, steinstrasse, ancillary procedures, and the use of medical expulsive therapy post-SWL.

Why do we need a Global SWL Study? Although SWL has been around since the 1980s, there are significant variations among the different centers and even among different urologists within a center. ¹¹ Therefore, a Global CROES Study on SWL would assess variations among different centers, lithotripters, and their associated outcomes. In addition, given that CROES has already collected data on PCNL and URS, it would be possible to perform matched case-controlled analysis to compare outcomes with different minimally invasive treatment options. Results of such a Global SWL Study would be important to make further recommendations for improving outcomes after SWL and further defining patient selection criteria for SWL in the modern era of flexible URS and laser lithotripsy.