Chi-Fai Ng et al., 2024: Effect of Focal Zone Size on Treatment Outcomes and Renal Injury Following Extracorporeal Shockwave Lithotripsy of Renal Calculi: A Prospective Randomized Study
Chi-Fai Ng , Chi Hang Yee, Jeremy Y C Teoh, Peter K F Chiu, Angel W Y Kong, Becky S Y Lau, Steven C H Leung, Ka Tak Wong, Winnie C W Chu
Department of Surgery, SH Ho Urology Center, The Chinese University of Hong Kong, Shatin, Hong Kong.
Department of Imaging and Intervention Radiology, The Chinese University of Hong Kong, Shatin, Hong Kong.
Abstract
Background: The narrower focal zone (FZ) size of modern lithotripter was considered as one of the factors that resulted in suboptimal treatment result of extracorporeal shockwave lithotripsy (SWL). Therefore, we investigate the efficacy and safety of standard narrow or extended (FZ) sizes in SWL for patients with renal stones. Materials and Methods: In this prospective study conducted between April 2018 and October 2022, patients with renal stones were randomized to receive SWL with either standard or extended FZ. Treatment was delivered using a Modulith SLX-F2 lithotripter with a maximum of 3000 shocks at 1.5 Hz. The primary outcome was treatment success 12 weeks after a single SWL session, defined as the absence of a stone or stone fragment <4 mm on computed tomography. Secondary outcomes included the incidence of perinephric hematoma, stone-free rate (SFR), and changes in the urinary levels of acute renal injury markers. Results: A total of 320 patients were recruited, and 276 patients were randomized into the two groups. The two groups had similar baseline parameters. The treatment success rate was significantly better for standard FZ (74.3%) than the extended FZ group (59.3%) (p = 0.009). Standard FZ also had a significantly better SFR (Grade-A, 36.8% vs 23.0%, p = 0.013) and less pain after treatment. Both groups had similar perinephric hematoma formation rates, unplanned hospital admission rates, and changes in urinary acute renal injury markers. Conclusions: The standard narrow FZ has better treatment efficacy and similar safety compared with the extended FZ during SWL for renal stones. This clinical trial has been registered in the public domain (CCRBCTR) under trial number CUHK_CCRB00510.
J Endourol. 2024 May;38(5):505-512. doi: 10.1089/end.2023.0662. Epub 2024 Apr 5.
PMID: 38482817 DOI: 10.1089/end.2023.0662
Comments 1
What a good paper! It is rare to find today a good randomized prospective study on single session ESWL.
Of course, there will be a debate on the applicability of the present data on the use of other shock wave machines.
I had a small problem with the definition of success and outcome measures.
“The primary outcome measure was defined as either a stone-free state or the presence of clinically insignificant residual fragments (smaller than 4 mm) as assessed by NCCT performed 12 weeks after a single session of SWL.” In text and tables the terms Succes, SFR and Grade-A SFR are used.
I was also surprised by the high hematoma rates which reminded me of our studies on the effects of HM-3 lithotripsy in the early 80ies. CT images within a few hours or days after ESWL frequently showed small subcapsular fluid collections, but our radiologists could not differentiate between seroma-like fluid and blood. And sonography a few days later was inconspicuous.
Peter Alken