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Prognostic Impact of Stone-Scoring Systems After Percutaneous Nephrolithotomy for Staghorn Calculi: A Single Center's Experience Over 10 Years.

INTRODUCTION
To investigate the prognostic factors associated with stone-free rate (SFR) and complications after percutaneous nephrolithotomy (PCNL) for the treatment of staghorn stone and to compare the predictive value and accuracy of three stone-scoring systems for the treatment success of staghorn stone.


PATIENTS AND METHODS
We retrospectively reviewed all patients undergoing PCNL at our center from June 2003 to June 2014. On the basis of noncontrast computed tomography (NCCT) scan images, we calculated Guy's score, S.T.O.N.E. nephrolithometry, and Clinical Research Office of the Endourological Society (CROES) nomogram to assess the association with stone-free status and complications. For statistical evaluation, univariate and multivariate logistic regression analyses were used.


RESULTS
During the study period, 886 cases had medical records available. Cases who underwent PCNL for the treatment of staghorn calculi accounted for 34.4% (305/886 cases). Preoperative NCCT was performed in 217 cases. The 217 procedures (205 patients, 12 simultaneous bilateral PCNLs) had a mean stone size of 1358.3 ± 760.7 mm(2), with 111 (51.2%) partial staghorn and 106 (48.8%) complete staghorn stones. The initial and overall SFRs of PCNL were 53.9% and 70.1%, respectively. The overall complication rate was 32.7% (71/217 cases). On a multivariate logistic regression analysis, independent predictors for SFR were number of involved calices, S.T.O.N.E. nephrolithometry, and pre-existent urinary tract infection (UTI) (odds ratios [ORs] = 1.311, 1.933, and 2.340, respectively). Stone burden was an independent risk factor for the development of complications on multivariate analysis (OR = 2.846 and p = 0.001).


CONCLUSION
The results of this study show that multiple involved calices, high grades of S.T.O.N.E. nephrolithometry, and pre-existent UTIs were associated with lower SFR after PCNL for staghorn calculi. Stone burden was an independent risk factor for the development of complications.