title: Multicenter External Validation and Comparison of Stone Scoring Systems in Predicting Outcomes After Percutaneous Nephrolithotomy.
abstract: Several scoring systems have recently emerged to predict stone-free rate (SFR) and complications after percutaneous nephrolithotomy (PCNL). We aimed to compare the most commonly used scoring systems (Guy's stone score, S.T.O.N.E. nephrolithometry, and CROES nomogram), assess their predictive accuracy for SFR and other postoperative variables, and develop a risk group stratification based on these scoring systems.
  
  
  
  We performed a retrospective review of patients who have had a PCNL at four academic institutions between 2006 and 2013. Primary outcome was SFR within 3 weeks of the surgery and secondary outcomes were operative time (OT), complications, and length of stay (LOS). We performed chi-squared, t-test, logistic, linear, and Poisson regressions, as well as receiver operating characteristics curve with area under the curve (AUC) calculation.
  
  
  
  We identified 586 patients eligible for analysis. Of these, 67.4% were stone free. Guy's, S.T.O.N.E., and CROES score were predictive of SFR on multivariable logistic regression (odds ratio [OR]: 1.398, 95% confidence interval [CI]: 1.056, 1.852, p = 0.019; OR: 1.417, 85% CI: 1.231, 1.631, p < 0.001; OR: 0.993, 95% CI: 0.988, 0.998, p = 0.004) and have similar predictive accuracy with AUCs of 0.629, 0.671, and 0.646, respectively. On multivariable linear regression, only S.T.O.N.E. was an independent predictor of longer OT (β = 14.556, 95% CI: 12.453, 16.660, p < 0.001). None of the scores were independent predictors of postoperative complications or a longer LOS. Poisson regression allowed for risk group stratification and showed the S.T.O.N.E. score and CROES nomogram to have the most distinct risk groups.
  
  
  
  The three evaluated scoring systems have similar predictive accuracy of SFR. S.T.O.N.E. has additional value in predicting OT. Risk group stratification can be used for patient counseling. Further research is needed to identify whether or not any is superior to the others with regard to clinical usefulness and predictive accuracy.
authors.affiliation: 1 Division of Urology, Department of Surgery, Western University , London, Ontario, Canada .|2 Department of Urology, Ghent University Hospital , Ghent, Belgium .
authors.forename: Thomas O
authors.initials: TO
authors.lastname: Tailly
authors.affiliation: 3 Department of Urology, University of California , Irvine, California.
authors.forename: Zhamshid
authors.initials: Z
authors.lastname: Okhunov
authors.affiliation: 4 Department of Radiology, Western University , London, Ontario, Canada .
authors.forename: Brandon R
authors.initials: BR
authors.lastname: Nadeau
authors.affiliation: 1 Division of Urology, Department of Surgery, Western University , London, Ontario, Canada .
authors.forename: Melissa Jessica
authors.initials: MJ
authors.lastname: Huynh
authors.affiliation: 3 Department of Urology, University of California , Irvine, California.
authors.forename: Kevin
authors.initials: K
authors.lastname: Labadie
authors.affiliation: 5 Department of Urology, University of Florida , Gainesville, Florida.
authors.forename: Arash
authors.initials: A
authors.lastname: Akhavein
authors.affiliation: 1 Division of Urology, Department of Surgery, Western University , London, Ontario, Canada .
authors.forename: Philippe D
authors.initials: PD
authors.lastname: Violette
authors.affiliation: 1 Division of Urology, Department of Surgery, Western University , London, Ontario, Canada .
authors.forename: Daniel
authors.initials: D
authors.lastname: Olvera-Posada
authors.affiliation: 1 Division of Urology, Department of Surgery, Western University , London, Ontario, Canada .
authors.forename: Husain
authors.initials: H
authors.lastname: Alenezi
authors.affiliation: 4 Department of Radiology, Western University , London, Ontario, Canada .
authors.forename: Justin
authors.initials: J
authors.lastname: Amann
authors.affiliation: 5 Department of Urology, University of Florida , Gainesville, Florida.
authors.forename: Vincent G
authors.initials: VG
authors.lastname: Bird
authors.affiliation: 3 Department of Urology, University of California , Irvine, California.
authors.forename: Jaime
authors.initials: J
authors.lastname: Landman
authors.affiliation: 6 The Smith Institute for Urology, North Shore LIJ Health System , New Hyde Park, New York.
authors.forename: Arthur D
authors.initials: AD
authors.lastname: Smith
authors.affiliation: 1 Division of Urology, Department of Surgery, Western University , London, Ontario, Canada .
authors.forename: John D
authors.initials: JD
authors.lastname: Denstedt
authors.affiliation: 1 Division of Urology, Department of Surgery, Western University , London, Ontario, Canada .
authors.forename: Hassan
authors.initials: H
authors.lastname: Razvi
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D019540:Area Under Curve; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000175:diagnosis* / Q000601:surgery*; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009403:Nephrostomy, Percutaneous / Q000009:adverse effects / Q000379:methods*; D049451:Nomograms; D061646:Operative Time; D011183:Postoperative Complications; D011184:Postoperative Period; D011379:Prognosis; D012372:ROC Curve; D012189:Retrospective Studies; D012306:Risk; D012720:Severity of Illness Index; D016896:Treatment Outcome