Stone-free rate post extracorporeal shock wave lithotripsy (ESWL) in the management of adult renal stones

Abstract

BACKGROUND: Extracorporeal Shock Wave Lithotripsy (ESWL) has been, and still is, one of the main kidney stone treatments available at Mater Dei Hospital in Malta and worldwide. This audit is aimed at identifying stone free rates (SFR) and stone factors that influence treatment outcomes.

METHODS: Retrospective data collection was conducted by collating stone density, size and type, skin to stone distance and stone free rates for all ESWL treatment sessions performed over a 14-year period between 2008 and 2022. Statistical analysis was performed to identify stone free rates after treatment and stone factors which were shown to be significant in influencing outcome.

RESULTS: The overall SFR was calculated as 30.1% from the 719 ESWL sessions included in this audit. Stone density in Hounsfield Unit (HU) was significantly associated with stone free status after treatment (p=0.0001). Stone size was also associated with SFR (p=0.001). Skin to stone distance, presenting and stone position were not significantly related to SFR.

CONCLUSION: The overall SFR was found to be lower than that quoted in most studies, even when accounting for the strict definition of complete clearance of the treated stone used. This audit should hopefully lead to development of treatment protocols in terms of multiple sessions and power ramping, as well as stricter follow-up and continuous re-audit to improve future outcomes.