Effect of Adjuvant Silodosin on Stone Clearance After Extracorporeal Shock Wave Lithotripsy for Renal Stones: A Randomised Controlled Trial

Background/Objectives: To evaluate whether adjunctive silodosin improves the stone-free rate (SFR) and clinical outcomes of extracorporeal shock wave lithotripsy (ESWL) for renal calculi. Methods: In this prospective randomised controlled trial, 100 adults with solitary radiopaque non-lower pole renal stones measuring 5–20 mm underwent single-session ESWL and were randomised (1:1) to receive either silodosin 8 mg once daily plus standard care or standard care alone for up to 12 weeks. Participants were followed up for three months. The primary outcome was SFR at three months on follow-up imaging. The secondary outcomes included time to stone clearance, renal colic episodes, analgesic requirement and adverse events. Results: At three months, the SFR was higher in the silodosin group than in the control group (68.0% vs. 50.0%; RR 1.36, 95% CI 0.97–1.90), but this difference did not reach statistical significance (p = 0.067). In a prespecified exploratory subgroup analysis, patients with stones measuring 10–20 mm showed a higher SFR with silodosin than controls (61.8% vs. 34.4%; p = 0.026), whereas no benefit was observed for stones measuring 5–9 mm (p = 0.803). Time-to-clearance analysis using Kaplan–Meier methods suggested earlier confirmed stone clearance in the silodosin group (hazard ratio 1.58, 95% CI 1.02–2.45; log-rank p = 0.036). Silodosin was also associated with fewer renal colic episodes and lower analgesic requirements. No serious drug-related adverse events were observed. Conclusions: This randomised controlled trial did not meet its primary endpoint because adjunctive silodosin did not significantly improve the overall SFR after ESWL. However, a possible benefit was observed in patients with renal stones measuring 10–20 mm, together with improved pain-related outcomes. These findings suggest that silodosin may have a role in selected patients, but the subgroup effects should be considered hypothesis-generating rather than definitive.