External Validation and Predictive Accuracy Assessment of Guy's Stone Score as a Preoperative Tool for Estimating Percutaneous Nephrolithotomy Outcomes.
OBJECTIVE
To externally validate Guy's stone score system and estimate its predictive accuracy.


METHODS
An analysis of 282 consecutive patients, who underwent a percutaneous nephrolithotomy, was performed. The association between Guy's stone score and several pre-, intra-, and postoperative parameters was assessed. A univariate and multivariate analysis was conducted to identify the independent predictors for stone-free rates. Area under the curve was used for predictive accuracy estimation.


RESULTS
Stone burden, multiple stone locations, number of stones, number of implicated caliceal groups, and Guy's stone score were significantly associated with stone-free outcomes. The multivariate analysis showed that Guy's stone score, number of stones, and number of implicated caliceal groups are independent predictors of stone-free status. Receiver operating characteristic curve analysis revealed a significant predictive accuracy for the Guy's stone score.


CONCLUSIONS
The present study externally validated Guy's stone score. Significant predictive ability combined with great predictive accuracy was found.
Department of Urology, Hadassah Hebrew University Medical Center , Jerusalem, Israel .
Stavros
S
Sfoungaristos
Department of Urology, Hadassah Hebrew University Medical Center , Jerusalem, Israel .
Amitay
A
Lorber
Department of Urology, Hadassah Hebrew University Medical Center , Jerusalem, Israel .
Ofer N
ON
Gofrit
Department of Urology, Hadassah Hebrew University Medical Center , Jerusalem, Israel .
Vladimir
V
Yutkin
Department of Urology, Hadassah Hebrew University Medical Center , Jerusalem, Israel .
Ezekiel H
EH
Landau
Department of Urology, Hadassah Hebrew University Medical Center , Jerusalem, Israel .
Dov
D
Pode
Department of Urology, Hadassah Hebrew University Medical Center , Jerusalem, Israel .
Mordechai
M
Duvdevani
D000328:Adult; D000368:Aged; D019540:Area Under Curve; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009403:Nephrostomy, Percutaneous / Q000379:methods*; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D055815:Young Adult