Importance: Shock wave lithotripsy (SWL) and ureteroscopy (URS) account for more than 90% of procedural interventions for kidney stones, which affect 1 in 11 persons in the United States. Efficacy data for SWL are more than 20 years old. Advances in URS, along with emerging evidence of reduced efficacy of modern lithotripters, have created uncertainty regarding the comparative effectiveness of these 2 treatment options.
Objective: To compare the effectiveness of SWL and URS to fragment or remove urinary stones in a large private payer cohort.
Design, setting, and participants: We performed a retrospective cohort study of privately insured beneficiaries who had an emergency department visit for a kidney stone and subsequently underwent SWL or URS. Using an instrumental variable approach to control for observed and unobserved differences between the 2 groups, we created a bivariate probit model to estimate the probability of repeat intervention following an initial procedure.
Main outcomes and measures: A second procedure (SWL or URS) within 120 days of an initial intervention to fragment or remove or a kidney stone.
Results: Following an acute care visit for a kidney stone, 21 937 patients (45.8%) underwent SWL and 25 914 patients (54.2%) underwent URS to fragment or remove the stone. After the initial URS, 4852 patients (18.7%) underwent an additional fragmentation or removal procedure compared with 5186 patients (23.6%) after the initial SWL (P < .001). After adjusting for observed and unobserved variables, the estimated probabilities of repeat intervention were 11.0%(95%CI, 10.9-11.1) following SWL and 0.3%(95%CI, 0.325-0.329) following URS.
Conclusions and relevance: Among privately insured beneficiaries requiring procedural intervention to remove a symptomatic stone, repeat intervention is more likely following SWL. For the marginal patient (as opposed to the average patient), the probability of repeat intervention is substantially higher.