Outcomes of Shockwave Lithotripsy for Upper Urinary-Tract Stones: A Large-Scale Study at a Single Institution

Abstract

Purpose: We investigated the risk factors having an impact on the achievement of stone-free status and on the success rate, as well as on the likelihood of recurrence, in patients undergoing shockwave lithotripsy. Patients and Methods: We evaluated the characteristics and outcomes of 3023 patients (3254 renal units) with upper urinary-tract stones who underwent SWL at the Funabashi Clinic over a 13-year period. We assessed the stone-free and success rates for 2844 patients (3061 renal units) 3 months post-SWL. We also determined the recurrence rate for the 1078 patients (1139 renal units) who had achieved stone-free status at that time. Results: Overall, stone-free status was achieved in 65.1% of patients, and the success rate was 85.7%. There were significant differences in the stone-free rates depending on patient age, history of urolithiasis, and presence of pyuria before SWL, as well as the number, location, size, and composition of the stones. Stones recurred in 326 of 1139 renal units (28.6%) during a mean follow-up of 36 months. The recurrence rates were 7.5%, 24.1%, and 33.0% after 1, 3, 5 years, respectively. Multiple stones, a history of urolithiasis, and stones located in the kidney or in both a kidney and a ureter significantly influenced recurrence. Multivariate analysis demonstrated that multiple stones were most significantly related to recurrence. Conclusion: Treatment with SWL has a low morbidity and high effectiveness. The number and location of stones and a history of urolithiasis significantly influence recurrence. Further studies of prophylactic therapy are required, especially for patients with these factors.