Ureteroscopy vs Shock Wave Lithotripsy for Lower Pole Renal Stones: Treatment Variation and Outcomes in a Surgical Collaborative

Abstract

Purpose: AUA guidelines recommend ureteroscopy (URS) or shock wave lithotripsy (SWL) for lower pole (LP) stones ≤ 1 cm, while SWL is second line for stones > 1 to 2 cm. In the era of increasing URS, there are limited data on the modality used and outcomes. We assessed treatment distribution, stone-free rates (SFRs), and unplanned health care.

Materials and methods: Using the Michigan Urological Surgery Improvement Collaborative registry, we identified URS and SWL cases for LP stones ≤ 2 cm (2016-2021). We assessed the frequency of patients receiving URS or SWL as a proportion of their LP treatment. A logistic model determined predictive probability of treatment modality. Differences in complete SFRs, postoperative emergency department visits, and hospitalizations were assessed by size (≤1 cm, >1-2 cm), adjusted for patient factors and correlation within practice/provider.

Results: There were 3645 procedures from 35 practices (209 surgeons); 2287 (62.7%) had SWL. Of the stones 80.2% were ≤ 1 cm. There was variation in modality based on practice (P < .001) and surgeon (P < .001). For stones ≤ 1 cm, the SFR was higher for URS (56% vs 39%; P < .001). There were no significant differences in SFRs for > 1 to 2 cm stones. Emergency department visits were higher after URS for stones ≤ 1 cm (odds ratio [OR]: 2.95, 95% CI: 1.7-5.0) but not for > 1 to 2 cm stones (OR: 0.97, 95% CI: 0.4-2.2). URS for stones ≤ 1 cm was associated with increased hospitalizations (OR: 4.67, 95% CI: 1.7-12.9) but not for stones > 1 to 2 cm (OR: 0.96, 95% CI: 0.4-2.2).

Conclusions: In Michigan, SWL is the chosen modality for LP stones ≤ 2 cm. For smaller stones, URS was more effective but had greater morbidity. For larger stones, both modalities demonstrated suboptimal efficacy. Our work demonstrates the need for interventions to improve outcomes.

Keywords: nephrolithiasis; quality improvement; retrograde intrarenal surgery; shock wave lithotripsy; ureteroscopy; urolithiasis.