Efficacy and cost-effectiveness of extracorporeal shock wave lithotripsy for solitary lower pole renal calculi.

PURPOSE We determined the efficacy of extracorporeal shock wave lithotripsy monotherapy and compared its cost-effectiveness with percutaneous nephrolithotomy for the management of lower pole renal calculi. MATERIALS AND METHODS The efficacy (stone-free rates at 3-months posttreatment) of shock wave lithotripsy with the modified Dornier HM3* machine was determined retrospectively in 114 patients with solitary lower pole renal calculi. Using cost data available from patient billing charges and efficacy data from the literature, the cost-effectiveness for percutaneous nephrolithotomy and shock wave lithotripsy as primary therapy was evaluated. To make this cost-effectiveness comparison, we developed a decision analysis model in which a patient in whom primary therapy failed was rendered stone-free with a secondary percutaneous nephrolithotomy procedure. RESULTS The stone-free rates of solitary lower pole stones with a size range of less than 10, 11 to 20 and greater than 20 mm. were 76, 74 and 33%, respectively, with a single shock wave lithotripsy treatment. Based on average treatment costs for shock wave lithotripsy and percutaneous nephrolithotomy, the model results show that for stone sizes less than 2 cm. primary lithotripsy therapy followed by nephrolithotomy for failed cases is the least costly approach. For stone sizes greater than 2 cm. primary percutaneous nephrolithotomy may be more cost-effective. CONCLUSIONS Whereas shock wave lithotripsy with the Dornier HM3 should be considered the initial treatment choice for most lower pole stones less than 2 cm., primary percutaneous nephrolithotomy should be considered for stones larger than 2 cm.