Tran TY et al, 2014: Triple D Score Is a Reportable Predictor of Shockwave Lithotripsy Stone-Free Rates.
Tran TY, McGillen K, Cone EB, Pareek G
Division of Urology, Warren Alpert Medical School of Brown University , Providence, Rhode Island.
Abstract
Purpose: Over the last decade, shockwave lithotripsy (SWL) success rates have been correlated with stone density, skin-to-stone distance
(SSD), and stone diameter. However, time constraints and the technical challenge of manual measurement often preclude utilization of these parameters. In this study, we describe a scoring system that accurately predicts SWL stone-free rates, is simple to calculate, and can
be easily included in the radiology report. Materials and Methods: Two hundred thirty-five patients who underwent SWL from 2011 to 2014 were evaluated. One hundred thirty-three had available preoperative imaging. Stone density, SSD, ellipsoid stone volume (ESV), and stone-free rates were determined. Receiver operator characteristic (ROC) curves were generated to determine cutoff values for each parameter. The Triple D Score was calculated based upon the number of cutoff values a stone fell below. Results: One hundred forty of the 235 patients (59.5%) who underwent SWL were stone free after single-session treatment. Seventy-six of the 133 (57.1%) patients with
available preoperative imaging were stone free. ESV, SSD, and stone density were significant predictors of SWL success. Based upon
the ROC curves, cutoffs of <150 μL for ESV, <12 cm for SSD, and <600 HU for stone density were established. A Triple D Score of 0,
1, 2, and 3 correlated with SWL success rates of 21.4%, 41.3%, 78.7%, and 96.1%, respectively. Conclusions: Readily available predictive tools are necessary to enhance SWL cost-effectiveness. The Triple D Score is simple to calculate and can be reported by radiologists. Incorporation of the Triple D Score into preoperative planning may increase the overall SWL success rates.
J Endourol. 2014 Sep 19. [Epub ahead of print]
Comments 1
The term wasteful spending appears more often in debates about the ever increasing health care costs. Publications that allow predicting success of ESWL help to reduce costs and increase the quality of treatment. This publication and the one by Sfoungaristos S, et al. (Sfoungaristos S, et al. Do we really need a KUB to predict stone radiopacity prior treatment with shockwave lithotripsy? Development and internal validation of a novel predictive model based on computed tomography parameters. J Endourol. 2014 Aug 8) are of interest in this respect.
The Triple D Score is easily calculated by data from the pre-ESWL CT imaging. Data from all cases which were stone free 4 to 6 weeks after one ESWL session were used for its construction. Only stone density (HU), skin-to-stone distance (SSD) and the ellipsoid stone volume (ESV) significantly contributed to the stone free rate. Some of the results were not what one would expect, like lower pole or mid ureteral stones being third and second best in terms of stone free rate. The number of cases was relatively small and with a larger number stone location could get a significant influence on the results. Applying the Triple D Score retrospectively 74 (55,6%) of the 133 cases would have been excluded from ESWL and be treated by URS or PNL.