Long-term stone recurrence rate after extracorporeal shock wave lithotripsy

We followed patients who were stone-free after extracorporeal shock wave lithotripsy (ESWL) to investigate the factors that contributed to recurrent calculi.

For longer than 5 years 903 patients without residual fragments 3 months after ESWL were enrolled in this study. Plain abdominal films and/or excretory urograms were evaluated every 6 months for recurrent stones on the side of ESWL. Patients who presented with colic pain or other complaints and who were suspected of having recurrent stones were also examined. Stone recurrence rates were calculated with the Kaplan-Meier method. We assessed the influence of patient age; size, location, composition and configuration of the original stones, and pyuria after ESWL on stone recurrence.

Mean followup was 25 months and stones recurred in 183 of 903 renal units (20.3%). Kaplan-Meier recurrence rates were 6.7, 28.0 and 41.8% after 1, 3 and 5 years, respectively. There was a significant correlation between stone recurrence and multiple stones on one hand, and pyuria after ESWL on the other hand. Stones recurred most frequently in the lower calix. Recurrent stones were passed without intervention in 33 cases, while ESWL was repeated in 53.

These data demonstrate the importance of long-term followup and the search for an effective prophylactic therapy to prevent recurrence.