Evaluation of Possible Predictive Variables for the Outcome of Shock Wave Lithotripsy of Renal Stones

Abstract

PurposeThe aim of this study was to evaluate possible predictive variables for the outcome of shock wave lithotripsy (SWL) of renal stones in a single center.Materials and MethodsBetween March 2008 and March 2010, a retrospective review was performed of 115 patients who underwent SWL for solitary renal stones. The patients' characteristics and stone size, location, skin-to-stone distance (SSD), and Hounsfield units (HU) of stone were reviewed. The impact of the possible predictors on the disintegration of the stones was evaluated by logistic regression analysis. Receiver operator characteristic (ROC) curves were generated to compare the predictive powers of the variables.ResultsSeventy-nine patients (68.7%) had successful outcomes, whereas 36 patients (31.3%) had residual stones. Significant differences were found in the mean size and mean HU of the stones (size: 8.34±3.58 mm vs. 13.57±5.41 mm, p<0.001; HU: 675.29±254.34 vs. 1,075.00±290.41, p<0.001). In the unadjusted model, age, stone size, and stone density were significant predictors. In the reduced model, stone density and size were significant predictors for the outcome of SWL. The area under the ROC curve (AUC) was significantly higher for stone density and size than for the other parameters, but the AUC between stone density and size did not differ significantly (stone density: 0.874, stone size: 0.827, p=0.388).ConclusionsStone density and size were significant predictors of the outcome of SWL for renal stones less than 2.0 cm in diameter. We should consider HU and stone size when making decisions on the treatment of renal stones.

Predictive Variables of Success in Extracorporeal Shock Wave Lithotripsy

“…The same ratio was also reported by Bozkurt, Wiesenthal, Chung, Keshvari, and El-Nahas [5,[10][11][12][13], and an almost identical one by Junuzovic [14]. The Chi-square test showed no significant differences between the male and female patients in the success rate of ESWL, which was consistent with the finding of Tavakkoli [15]; whereas, Gupta and Park reported a higher rate of ESWL success in male patients [8,16]. The overall success rate of ESWL in the present study was 71%.…”

“…However, different success rates have been reported in various studies. For example, the overall success rate reported in the studies carried out Abdel, Park, Saeidi, and Murota-Kawano were 87, 68.7, 55, and 94.5%, respectively [8,[17][18][19]. Moreover, Jee reported a 90.9% overall success rate in the treatment of renal stones in children [20].…”

“…Obek also estimated the effectiveness rates of ESWL in breaking up the stones in the lower, middle, and upper ureter were 36, 46, and 41%, respectively [7]. Park reported stone density and size to be significant predictors of effectiveness of ESWL in breaking kidney stones smaller than 20mm [8]. According to Chaussy, ESWL was the front-line treatment of calcium stones larger than 10mm [9].…”

Analyzing the Effect of Distance from Skin to Stone by Computed Tomography Scan on the Extracorporeal Shock Wave Lithotripsy Stone-Free Rate of Renal Stones

“…In this study, we found no significant correlation between stone size and the stone-free rate. However, stone size has been reported in other studies as a significant predictor of the results of ESWL [17,19,20]. This is because of different stone characteristics such as stone density and location.…”

The S.T.O.N.E. Score: A new assessment tool to predict stone free rates in ureteroscopy from pre-operative radiological features

“…Hounsfield Units has commonly been reported to be a significant factor in shock-wave lithotripsy (23). Chung et al reported a statistical difference between successful and unsuccessful ESWL (675.29 versus 1075.00, respectively).…”