title: Prediction of single procedure success rate using S.T.O.N.E. nephrolithometry surgical classification system with strict criteria for surgical outcome.
abstract: OBJECTIVE
  To evaluate the S.T.O.N.E. nephrolithometry scoring system for percutaneous nephrolithotomy using computerized tomography (CT) imaging with strict criteria for stone clearance.
  
  
  METHODS
  We analyzed a cohort of 122 patients who consecutively underwent primary percutaneous nephrolithotomy from July 2010 to March 2012 at our university-based referral hospital. All patients routinely have preoperative and postoperative CT imaging for stone burden determination. Primary outcome (residual stone) was scored as 0-2, 3-4, and >4 mm. All S.T.O.N.E. nephrolithometry parameters were recorded and scored as per published definition. The t test was used for continuous variables, and the chi-square testing or the Fisher exact test (when counts were small) was used for categorical covariates. S.T.O.N.E. score correlation with stone-free status was analyzed by logistic regression.
  
  
  RESULTS
  Nephrolithometry score ranged from 5 to 13 with a mean of 9.5. Postoperative CT for residual stone showed 67 (54.9%), 26 (21.3%), and 29 (23.8%) patients had 0-2, 3-4, and >4 mm residual stone, respectively. Mean nephrolithometry scores for residual stone of 0-2, 3-4, and >4 mm were 8.87, 9.73, and 10.79 respectively (P <.0001). There were 11 (9.8%) complications.
  
  
  CONCLUSIONS
  With use of strict CT imaging criteria for assessment of residual stone status, the S.T.O.N.E. scoring system is reproducible and predictive of treatment success. Further investigation is required to both validate this model and to determine if other predictive parameters will improve it as a predictive model.
authors.affiliation: Department of Urology, University of Florida, Gainesville, FL.
authors.forename: Arash
authors.initials: A
authors.lastname: Akhavein
authors.affiliation: Department of Urology, University of Florida, Gainesville, FL.
authors.forename: Carl
authors.initials: C
authors.lastname: Henriksen
authors.affiliation: Department of Urology, University of Florida, Gainesville, FL.
authors.forename: Jamil
authors.initials: J
authors.lastname: Syed
authors.affiliation: Department of Urology, University of Florida, Gainesville, FL. Electronic address: vincent.bird@urology.ufl.edu.
authors.forename: Vincent G
authors.initials: VG
authors.lastname: Bird
mesh_terms: D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000145:classification* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous; D011379:Prognosis; D012074:Remission Induction; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed