Analysis of Factors Affecting Stone Recurrence after Extracorporeal Shock Wave Lithotripsy

Cho, Myoung Keun; Rim, Hee Kwan; Rim, Joung Sik

Abstract

PURPOSE: A retrospective analysis was performed to investigate the factors that affect stone recurrence in patients who were stone-free after extracorporeal shock wave lithotripsy(SWL).
MATERIALS AND METHODS
From February 1990 to December 1992, 1039 patients were treated by SWL with EDAP LT-01+ lithotriptor. Among them 200 patients were followed up at 60 months. Fifty eight(29.0%) of 200 patients had recurrent stone after SWL. We analysed the patients according to patient age, sex, location, multiplicity and size of the original stones, serum calcium and uric acid level, urinary calcium and uric acid level at presentation, anatomical abnormality and pyuria after SWL as possible factors affecting stone recurrence.
RESULTS
Mean age of the patients was 43.6 years(range 7 to 81) and there were 115 male and 85 female patients with sex ratio 1.35:1. Age and sex did not affect stone recurrence. The recurrence rates according to the stone location were 100%(1/1) for staghorn calculi, 28.6%(2/7) for pelvic stones, 26.2%(16/61) for single calyceal stone, 47.8%(11/23) for multiple calyceal stones and 29.7%(41/138) for ureteral stones. Stone location did not affect stone recurrence. 16(47.0%) of 34 renal units with multiple stones had recurrent stones, whereas 55(28.1%) of 196 renal units with single stone recurred. Multiplicity of the stone was the risk factor for stone recurrence(p<0.05). The stone size(renal unit) of less than 20mm were identified in 213 and 64(30.0%) of them had recurrent stones, whereas stone size(renal unit) of more than 20mm were identified in 17 and 7(41.2%) of them had recurrent stones. More than 20mm of the stone size was the risk factor for stone recurrence(p<0.05). Hypercalcemia, hyperuricemia, hypercalciuria, and hyperuricosuria did not affect stone recurrence. 14(28.6%) of 49 patients who had pyuria after SWL had recurrent stones, whereas sterile urine after SWL were noted in 151 and 44(29.1%) of them had recurrent stones. Pyuria after SWL did not affect stone recurrence. Anatomical abnormality was noted in 5 patients and 4(80%) of them showed recurrence, but there was no statistical significance due to small populations.
CONCLUSIONS
Multiplicity and size of the stones were the risk factor for stone recurrence. But patient age, sex, location of the original stones, serum calcium and uric acid level, urinary calcium and uric acid level at presentation and pyuria after SWL did not affect stone recurrence.