Predictors of Success after Extracorporeal Shock Wave Lithotripsy (ESWL) for Renal Calculi Between 20—30 mm: A Multivariate Analysis Model

Abstract

The first-line management of renal stones between 20—30 mm remains controversial. The Extracorporeal Shock Wave Lithotripsy (ESWL) stone-free rates for such patient groups vary widely. The purpose of this study was to define factors that have a significant impact on the stone-free rate after ESWL in such controversial groups. Between January 1990 and January 2004, 594 patients with renal stones 20—30 mm in length underwent ESWL monotherapy. Stone surface area was measured for all stones. The results of treatment were evaluated after 3 months of follow-up. The stone-free rate was correlated with stone and patient characteristics using the Chi-square test; factors found to be significant were further analyzed using multivariate analysis.Repeat ESWL was needed in 56.9% of cases. Post-ESWL complications occurred in 5% of cases and post-ESWL secondary procedures were required in 5.9%. At 3-month follow-up, the overall stone-free rate was 77.2%. Using the Chi-square test, stone surface area, location, number, radiological renal picture, and congenital renal anomalies had a significant impact on the stone-free rate. Multivariate analysis excluded radiological renal picture from the logistic regression model while other factors maintained their statistically significant effect on success rate, indicating that they were independent predictors. A regression analysis model was designed to estimate the probability of stone-free status after ESWL. The sensitivity of the model was 97.4%, the specificity 90%, and the overall accuracy 95.6%.Stone surface area, location, number, and congenital renal anomalies are prognostic predictors determining stone clearance after ESWL of renal calculi of 20—30 mm. High probability of stone clearance is obtained with single stone ≤400 mm2 located in renal pelvis with no congenital anomalies. Our regression model can predict the probability of the success of ESWL in such controversial groups and can define patients who would need other treatment modality.

Comparison of the outcomes of complete supine percutaneous nephrolithotomy in patients with radiopaque and radiolucent kidney stones

“…Also, no correlation was found between ESWL success rates and stone opacity in two other studies. [13,20] Operation time was not different between the two groups in univariate analysis in our study. Falahatkar et al [21] also did not report any relationship between surgery time and stone opacity in complete supine PCNL procedures.…”

Treatment of Renal Stones ≥20 mm with Extracorporeal Shock Wave Lithotripsy

“…In our study, the stone-free rates were 72.0 and 40.0% for patients with stones ≤400 and >400 mm 2 , respectively. These rates are lower than those reported by El-Assmy et al [14]. However, in our series, the number of shocks delivered per case was no more than 2,500, which was lower than the value reported in their study (3,000 shocks); additionally, in our study, the kilovoltage ranged from 10 to 16, which was also lower than that used in their study.…”

Stone size and quality of life: A critical evaluation after extracorporeal shock wave lithotripsy

“…Although ESWL is the management of choice for most stones with its efficient and safe natüre (2); studies demonstrated that despite an effective disintegration, sponta neous passage and in some cases removal of the fragments may be needed for a completely SF status. Long-term follow-up data in large number of patients has clearly shown that 23% to 54% of the cases undergoing ESWL may have residing fragments after this procedure (11,12). Regarding the clinical course after ESWL although majority of disintegrated stone particles may pass spontaneously or stay in situ asymptomatic; they may be symptomatic and/or obstructive in a certain percent of the cases.…”

“…In their original study, Abe et al reported that of the 267 patients undergoing ESWL for stones sizing between 20 and 30 mm.,46% were SF, while residual fragment were present in 54% (11). Thus, despite a safe and successful disintegration, depending on the stone size, SFR could vary in a considerable percent of the cases (6,12). The associated symptoms and morbidity during the passage of disintegrated fragments might have significant effects on these patients' QoL (4,13,14).…”