Residual Stone Volume Predicts Health Care Consumption and Stone Events: Analysis of Two-Year Results of the ASPIRE...

The ASPiration to Improve Renal Calculi Removal Effectiveness study showed steerable ureteroscopic renal evacuation (SURE) with CVAC that significantly reduced residual stone volume at 30 days vs standard ureteroscopy (URS). This report presents 2-year health care consumption and stone events (SE) and their link to residual stone volume and other variables (n = 101 at primary end point; n = 93 at 2 years).

Logistic regression identified predictors of health care consumption events (HCEs), that is, emergency department visits, hospitalization, surgical retreatment, and SE across the study population. Incidence was compared between the treatment groups with Kaplan-Meier survival analysis.

At 2 years, residual stone volume was significantly associated with both HCEs and SE. For every 100 mm³ increase in residual stone volume, the HCE risk increased by 50% to 54%, and the SE risk increased by 70%. Stone-free rate, the number of residual fragments (RFs), and RF total stone burden (based on diameter) were not predictors. Significantly fewer HCEs occurred in the SURE group (3 vs 20 events, p = 0.0004). Survival analysis confirmed this (4.3% vs 20%, log-rank p = 0.02), with a 73% risk reduction (hazard ratio 0.27, 95% Cl 0.09-0.80, p = 0.02). Fewer SE occurred in the SURE group, although not statistically significant. These subjects also had longer event-free survival.

High-quality volumetric analysis supports evaluation of stone removal therapies, as residual stone volume predicts HCEs and SE. SURE significantly reduces the downstream incidence and risk of HCEs compared with standard URS.