Recurrence Rate and Risk Factors for Stone Recurrence after Successful Extracorporeal Shock Wave Lithotripsy: 5-year-follow-up Study

Abstract

Purpose: After treatment, urinary stones are known to have high recurrence rates. Therefore, the recurrence rates and risk factors for recurrence after successful extracorporeal shock wave lithotripsy (ESWL) were investigated to help in the decisions making for the treatment of patients with urinary stones. Materials and Methods: Between January 1999 and December 2000, 415 patients (444 renal units), treated by ESWL due to urinary stones, were followed up for 5 years using either KUB or sonography. Treatment success was defined as complete passage of the stone or insignificant stone fragments, less than 3mm in diameter, remaining. The stone recurrence rates were calculated using the Kaplan-Meier method. The possible risk factors for recurrence, such as sex, age, familial history of urinary stones, abnormal metabolic finding, pyuria after ESWL, stone location, size and multiplicity, were analyzed. Results: The overall number of recurrent stones was 82 in 444 renal units (18.5%). Using the Kaplan-Meier method, the recurrence rates were determined as 7.5, 17.8, 34.8, 39.8 and 45.8%, respectively, for each year upto 5 years. Among the many possible risk factors for a recurrence, the stone location (especially lower calyx) and multiplicity were found to be significant (p=0.042, p=0.009). Conclusions: Since the long term recurrence rates of the urinary stones can be as high as 45.8%, patients should be informed of this fact prior to treatment with ESWL. Especially, those patients with multiple or lower calyx stones should be followed-up more carefully. (Korean J Urol 2007; 48:49-53) ꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏ