Nozumi K. et al., 2024: Stone at the same location for 2 months predicts impacted stones and stone-free status after shock wave lithotripsy for ureteral stones: A Funabashi clinic expert study
Kazuyoshi Nozumi 1, Shinichi Sakamoto 1 2, Xue Zhao 2, Sangjon Pae 1 2, Takaaki Tamura 1 2, Kazumi Taguchi 3, Yasutaka Yamada 2, Yusuke Goto 4, Yusuke Imamura 2, Tomokazu Sazuka 2, Yusuke Awa 1, Takahiro Yasui 3, Kuniyoshi Nozumi 1, Yukio Naya 4, Koichiro Akakura 5, Tomohiko Ichikawa 2
1Funabashi Clinic, Funabashi, Chiba, Japan.
2Department of Urology, Chiba University Graduate School of Medicine, Chiba, Japan.
3Department of Nephro-Urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
4Department of Urology, Teikyo University Chiba Medical Center, Chiba, Japan.
5Department of Urology, Japan Community Health Care Organization, Mishima General Hospital, Sizuoka, Japan.
Abstract
Objectives: To evaluate the success rate of shock wave lithotripsy and identify predictors of stone-free status after shock wave lithotripsy for ureteral stones, focusing on the impact of stones remaining in the same location for 2 months (SSL2).
Methods: A retrospective analysis was conducted on 501 patients with ureteral stones treated with shock wave lithotripsy by expert surgeons (each with over 1000 shock wave lithotripsy operations) at a single Japanese institution in 2020. Logistic regression analysis identified predictors of stone-free status, including stone length, skin-to-stone distance, stone density (Hounsfield Unit), Hounsfield Unit above/below the stone, stone position, and duration of stone at the same location (SSL2).
Results: Ninety patients were excluded, resulting in 411 patients undergoing an average of 1.15 ± 0.4 sessions (range: 1-4). 344 patients (83.7%) achieved stone-free status after a single session. The overall 1-month stone-free rate was 71.4%, and the 3-month stone-free rate was 88.8%. Stone at the same location ≥2 months (SSL2) was an independent predictor of 1-month stone-free status (odds ratio = 2.25, 95%CI: 1.10-4.57, p = 0.025), while mean stone density ≥ 813 HU was an independent predictor of 3-month stone-free status (odds ratio = 2.66, 95% CI: 1.10-6.45, p = 0.03).
Conclusion: Stone at the same location ≥2 months (SSL2) was a potent predictor of 1-month and 3-month stone-free status. This condition is associated with impacted stones and can aid in decision-making for shock wave lithotripsy treatment selection.
Int J Urol. 2024 Dec 30. doi: 10.1111/iju.15662. Online ahead of print. PMID: 39740093
DOI: 10.1111/iju.15662
Comments 1
In this report on SWL-results of ureteral stones, there are two aspects that need special attention.
First, the SWL treatments only were carried out by “expert surgeons”, meaning that each one of the three operators had experience of at least 1000 treatments. Although there obviously was a marked difference within the group, they all seemed to have sufficient experience of SWL. This specific information is of great value given the considerable variation in experience among technicians, nurses and young colleagues.
Another interesting point is the introduction of the SSL2, defined as stones remaining in the same location >= 2 months. The authors show that SSL2 was a predictor of stone-free rates 1 and 3 months after SWL. The stone-free rates after 3 months were 83.3% and 91.4% in SSL2-positive and SSL2-negative patients, respectively. But although SSL2 is a useful variable to classify a ureteral stone as impacted, it is important to understand that for many patients the initial location is unknown. Moreover, there is no information on how long time the stone has been in the final position.
The interested reader can find other valuable information in the article on stone characteristics, surgical experience and lithotripter equipment, but nothing of novelty.
Hans-Göran Tiselius