title: Triple D Score is a reportable predictor of shockwave lithotripsy stone-free rates.
abstract: OBJECTIVE
  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.
  
  
  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.
authors.affiliation: 1 Division of Urology, Warren Alpert Medical School of Brown University , Providence, Rhode Island.
authors.forename: Timothy Y
authors.initials: TY
authors.lastname: Tran
authors.forename: Kathryn
authors.initials: K
authors.lastname: McGillen
authors.forename: Eugene Blanchard
authors.initials: EB
authors.lastname: Cone
authors.forename: Gyan
authors.initials: G
authors.lastname: Pareek
mesh_terms: D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging*; D008096:Lithotripsy / Q000379:methods; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012867:Skin / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed