title: External Validation and Evaluation of Reliability and Validity of the Modified Seoul National University Renal Stone Complexity Scoring System to Predict Stone-Free Status After Retrograde Intrarenal Surgery.
abstract: OBJECTIVE
  The modified Seoul National University Renal Stone Complexity scoring system (S-ReSC-R) for retrograde intrarenal surgery (RIRS) was developed as a tool to predict stone-free rate (SFR) after RIRS. We externally validated the S-ReSC-R.
  
  
  METHODS
  We retrospectively reviewed 159 patients who underwent RIRS. The S-ReSC-R was assigned from 1 to 12 according to the location and number of sites involved. The stone-free status was defined as no evidence of a stone or with clinically insignificant residual fragment stones less than 2 mm. Interobserver and test-retest reliabilities were evaluated. Statistical performance of the prediction model was assessed by its predictive accuracy, predictive probability, and clinical usefulness.
  
  
  RESULTS
  Overall SFR was 73.0%. The SFRs were 86.7%, 70.2%, and 48.6% in low-score (1-2), intermediate-score (3-4), and high-score (5-12) groups, respectively (p<0.001). External validation of S-ReSC-R revealed an area under the curve (AUC) of 0.731 (95% CI 0.650-0.813). The AUC of the three-titered S-ReSC-R was 0.701 (95% CI 0.609-0.794). The calibration plot showed that the predicted probability of SFR had a concordance comparable to that of observed frequency. The Hosmer-Lemeshow goodness of fit test revealed a p-value of 0.01 for the S-ReSC-R and 0.90 for the three-titered S-ReSC-R. Interobserver and test-retest reliabilities revealed an almost perfect level of agreement.
  
  
  CONCLUSIONS
  The present study proved the predictive value of S-ReSC-R to predict SFR following RIRS in an independent cohort. Interobserver and test-retest reliabilities confirmed that S-ReSC-R was reliable and valid.
authors.affiliation: 1 Department of Urology, Seoul Metropolitan Government-Seoul National University , Boramae Medical Center, Seoul, Korea.
authors.forename: Juhyun
authors.initials: J
authors.lastname: Park
authors.affiliation: 2 Department of Urology, Seoul National University Hospital , Seoul, Korea.
authors.forename: Minyong
authors.initials: M
authors.lastname: Kang
authors.affiliation: 2 Department of Urology, Seoul National University Hospital , Seoul, Korea.
authors.forename: Chang Wook
authors.initials: CW
authors.lastname: Jeong
authors.affiliation: 3 Department of Biostatistics, Seoul Metropolitan Government-Seoul National University , Boramae Medical Center, Seoul, Korea.
authors.forename: Sohee
authors.initials: S
authors.lastname: Oh
authors.affiliation: 4 Department of Urology, Sanggye Paik Hospital , Seoul, Korea.
authors.forename: Jeong Woo
authors.initials: JW
authors.lastname: Lee
authors.affiliation: 1 Department of Urology, Seoul Metropolitan Government-Seoul National University , Boramae Medical Center, Seoul, Korea.
authors.forename: Seung Bae
authors.initials: SB
authors.lastname: Lee
authors.affiliation: 1 Department of Urology, Seoul Metropolitan Government-Seoul National University , Boramae Medical Center, Seoul, Korea.
authors.forename: Hwancheol
authors.initials: H
authors.lastname: Son
authors.affiliation: 1 Department of Urology, Seoul Metropolitan Government-Seoul National University , Boramae Medical Center, Seoul, Korea.
authors.forename: Hyeon
authors.initials: H
authors.lastname: Jeong
authors.affiliation: 1 Department of Urology, Seoul Metropolitan Government-Seoul National University , Boramae Medical Center, Seoul, Korea.
authors.forename: Sung Yong
authors.initials: SY
authors.lastname: Cho
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000175:diagnosis / Q000601:surgery*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000379:methods*; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies