Predicting the Stone-Free Status of Percutaneous Nephrolithotomy with the Machine Learning System.

Purpose: The study aimed to create a machine learning model (MLM) to predict the stone-free status (SFS) of patients undergoing percutaneous nephrolithotomy (PCNL) and compare its performance to the S.T.O.N.E. and Guy's stone scores. Patients and Methods: This is a retrospective study that included 320 PCNL patients. Pre-operative and post-operative variables were extracted and entered into three MLMs: RFC, SVM, and XGBoost. The methods used to assess the performance of each were mean bootstrap estimate, 10-fold cross-validation, classification report, and AUC. Each model was externally validated and evaluated by mean bootstrap estimate with CI, classification report, and AUC. Results: Out of the 320 patients who underwent PCNL, the SFS was found to be 69.4%. The RFC mean bootstrap estimate was 0.75 and 95% CI: [0.65-0.85], 10-fold cross-validation of 0.744, an accuracy of 0.74, and AUC of 0.761. The XGBoost results were 0.74 [0.63-0.85], 0.759, 0.72, and 0.769, respectively. The SVM results were 0.70 [0.60-0.79], 0.725, 0.74, and 0.751, respectively. The AUC of Guy's stone score and the S.T.O.N.E. score were 0.666 and 0.71, respectively. The RFC external validation set had a mean bootstrap estimate of 0.87 and 95% CI: [0.81-0.92], an accuracy of 0.70, and an AUC of 0.795, While the XGBoost results were 0.84 [0.78-0.91], 0.74, and 0.84, respectively. The SVM results were 0.86 [0.80-0.91], 0.79, and 0.858, respectively. Conclusion: MLMs can be used with high accuracy in predicting SFS for patients undergoing PCNL. MLMs we utilized predicted the SFS with AUCs superior to those of GSS and S.T.O.N.E scores.

High stone-free rate immediately after suctioning flexible ureteroscopy with Intelligent pressure-control in treating upper urinary tract calculi.

BACKGROUND: The retrospective observational study aimed to evaluate the safety and efficacy of suctioning flexible ureteroscopy with Intelligent pressure-control (SFUI) on treating upper urinary tract calculi in a large cohort. METHODS: Between July 2020 and August 2021, 278 patients with upper urinary tract calculi who underwent SFUI in our hospital were enrolled. Outcomes were stone-free rate (SFR) in one session and one-month after SFUI treatment, and complications scored by the Clavien-Dindo classification. RESULTS: A total of 310 kidneys underwent SFUI were included. The median surgery time was 75 min (ranged 60-110 min). One session and one-month SFRs were 80.65% and 82.26%, respectively. The one-session SFR was ≧ 87% in patients with Guy's stone score of Grade I among stone size < 40 mm. Risk factors for unsuccessful stone-free in one session were stone history (adjusted odds ratio (aOR): 2.39, 95% confidence interval (CI): 1.21-4.73), stone size of 40-49 mm (aOR: 4.37, 95% CI: 1.16-16.45), Guy's stone score ≧ Grade II (Grade II, aOR: 3.54, 95% CI: 1.18-10.59; Grade III, aOR: 10.95, 95% CI: 2.65-45.25). The incidence of Clavien-Dindo grade II-III complication was 3.26%. Complication is associated with Guy's stone score III (aOR: 22.36, 95% CI: 1.81-276.36). CONCLUSION: SFUI shows good safety and efficiency on treating upper urinary tract calculi. Patients with stone size < 40 mm or Guy's stone score of Grade I have a high chance to reach stone-free after SFUI treatment.

Predicting the Stone-Free Status of Percutaneous Nephrolithotomy With the Machine Learning System: Comparative Analysis With Guy's Stone Score and the S.T.O.N.E Score System.

Purpose: The aim of the study was to use machine learning methods (MLMs) to predict the stone-free status after percutaneous nephrolithotomy (PCNL). We compared the performance of this system with Guy's stone score and the S.T.O.N.E score system. Materials and Methods: Data from 222 patients (90 females, 41%) who underwent PCNL at our center were used. Twenty-six parameters, including individual variables, renal and stone factors, and surgical factors were used as input data for MLMs. We evaluated the efficacy of four different techniques: Lasso-logistic (LL), random forest (RF), support vector machine (SVM), and Naive Bayes. The model performance was evaluated using the area under the curve (AUC) and compared with that of Guy's stone score and the S.T.O.N.E score system. Results: The overall stone-free rate was 50% (111/222). To predict the stone-free status, all receiver operating characteristic curves of the four MLMs were above the curve for Guy's stone score. The AUCs of LL, RF, SVM, and Naive Bayes were 0.879, 0.803, 0.818, and 0.803, respectively. These values were higher than the AUC of Guy's score system, 0.800. The accuracies of the MLMs (0.803% to 0.818%) were also superior to the S.T.O.N.E score system (0.788%). Among the MLMs, Lasso-logistic showed the most favorable AUC. Conclusion: Machine learning methods can predict the stone-free rate with AUCs not inferior to those of Guy's stone score and the S.T.O.N.E score system.

Evaluation and comparison of S.T.O.N.E. and Guy's scoring systems for predicting percutaneous nephrolithotomy outcomes in supine position.

BACKGROUND: Percutaneous nephrolithotomy (PCNL) was applied in the prone position until recently. But also, in recent years supine positions was applied in patients with kidney stones. Predicting how much renal stones can be cleared after surgery and possibility of complications is an important question for both surgeons and patients. Therefore different scoring systems are used to evaluate outcomes of PCNL before surgery. PATIENTS AND METHODS: Between 2018 and 2020, 80 patients with renal stone who underwent PCNL in the supine position were evaluated preoperatively by S.T.O.N.E. and Guy's scoring systems (GSS). The predictions of both scoring systems for stone-free and complication rates in patients who underwent PCNL in the supine position were evaluated. Also, these scoring systems were compared among themselves for reliability. RESULT: In both scoring systems, there was a statistically significant difference between postoperative stone-free (SF) and residual stone (RS) of patients and in predicting the likelihood of complications in patients. No statistically significant difference was found between the two scoring systems in predicting the stone-free rate. CONCLUSION: Our findings revealed that S.T.O.N.E. nephrolithometry and Guy's score systems can be used effectively to predict stone-free rate, complications, and operation duration in supine position PCNL for renal stones.

Evaluation of various nephrometric scoring system for nephrolithiasis to predict stone free status after percutaneous nephrolithotomy: A comparative study.

BACKGROUND: The CROES Nephrolithometry nomogram, S.T.O.N.E. Nephrolithometry Score and Guy's stone score were introduced for stratification of kidney stones disease on the basis of quantitative stone burden and its distribution. Till date there has been very limited data on head to head comparison of the existing scoring systems. Comparison and analyses among the scoring system helps in further refinement of these systems along with development of new more effective and broadly acceptable nomogram. OBJECTIVE: Predictability of the stone-free status (SFS) and post-operative complication after PCNL by various scoring systems (The CROES nomogram, S.T.O.N.E. nephrolithometry score and Guy's stone score). MATERIALS AND METHODS: Total 100 adult patients underwent PCNL after considering inclusion and exclusion criteria. All patients underwent Preoperative NCCT scan, investigations of blood (Hb%, PCV, bleeding and coagulation profile, urea, and creatinine), and urine (RE/ME and C/S), Postoperative X ray KUB/NCCT. RESULTS: ROC curves were developed for each scoring system to determine the accuracy to predict stone free status. We found CS had significantly higher AUC than other scoring systems [p-value for CS vs GSS = 0.0091 & CS vs SS = 0.000]. So CS has higher accuracy to predict stone free status. None of the scoring system had shown significantly higher AUC than other scoring system in predicting complication. CONCLUSION: CROES Nephrolithometry nomogram is most accurate to predict preoperative stone-free rate. All scoring systems can equally predict perioperative complications and other variables.

Role of Preoperative Renal Stone Complexity Assessment by Guy's Stone Score as a Predictor of Percutaneous Nephrolithotomy Outcomes.

INTRODUCTION: Various nephrolithometric scoring systems have recently emerged to predict the outcomes of percutaneous nephrolithotomy (PCNL). However, there is no consensus upon an ideal tool. The current study aimed to assess the correlation between Guy's stone score (GSS) and PCNL outcomes. METHOD: This was a hospital-based observational study of 2-year duration. All patients electively undergoing PCNL for renal stones during the study period were included. Based on the imaging findings, the stones were categorized as simple (GSS I & II) and complex (GSS III & IV). The association between GSS and duration of the procedure, the number of percutaneous tracts needed, stone-free rate (SFR), and the severity of complications based on modified Clavien classification and postoperative stay were assessed. RESULTS: Total number of the patients studied were 100 (n = 100), and most of the patients were in the category of GSS II (51%). Post-extrapolation of χ2 to Pearson's test, GSS demonstrated a significant association with duration of surgery, the number of percutaneous tracts needed, the severity of complications, and SFR. CONCLUSIONS: Preoperative assessment of stone complexity by using GSS effectively correlated with SFR as well as other PCNL outcomes. Hence, we recommend utilizing this predictive tool for standardized documentation, preoperative planning, and better patient counseling.

Comparison of STONE score, Guy's stone score and Clinical Research Office of the Endourological Society (CROES) score as predictive tools for percutaneous nephrolithotomy outcome: a prospective study.

OBJECTIVE: To evaluate which among the three scoring systems used to predict stone-free status (SFS) after percutaneous nephrolithotomy (PCNL), namely Guy's stone score (GSS), STONE nephrolithometry score and Clinical Research Office of the Endourological Society (CROES) nephrolithometry nomogram, is the most accurate predictor of SFS. METHOD AND MATERIALS: We prospectively included all patients who underwent PCNL (tract size >24 F) at our hospital between July 2017 and January 2019. All demographic and peri-operative data were tabulated including calculation of GSS, STONE score and CROES nomogram score using preoperative computed tomography. Comparison of the 'stone-free' group and 'residual-stone' group was carried out using standard statistical methods. RESULTS: A total of 252 patients were enrolled. The mean GSS, STONE score and CROES score in the stone-free group was 1.60, 6.98 and 212.27, respectively, and in the residual stone group group it was 2.93, 8.98 and 129.89, respectively (P < 0.001 in each). Receiver-operating characteristic (ROC) curves showed that all three scoring systems had similar predictive accuracy for post-PCNL SFS, with STONE score having the highest area under the ROC curve value (0.852). GSS was significantly associated with operating time, estimated blood loss (EBL) and length of hospital stay (LOS; P < 0.001 in each). STONE score and CROES score were both significantly associated with EBL (P = 0.029 and 0.001, respectively). CONCLUSION: All three scoring systems are equally predictive of post-PCNL SFS. EBL is significantly associated with all three scoring systems, while GSS is also associated with operating time and LOS.

Guy's Stone Score as a Predictor for Stone-Free Rate and Complications in Percutaneous Nephrolithotomy: A Single-Center Report from a Stone Belt Country.

OBJECTIVES: To evaluate Guy's Stone Score (GSS) as a grading system for the complexity of renal calculi before percutaneous nephrolithotomy (PCNL) and as a predictor for stone-free rate (SFR) and potential complications in the setting of a developing country with many cases of advanced complex stone disease. PATIENTS AND METHODS: We performed a prospective study on 115 patients with renal stones who had PCNL between August 2017 and October 2018. Stone complexity was classified according to GSS using preoperative imaging. The rates of perioperative complications were assessed using the Clavien grading system, and the SFR was assessed in the 3rd postoperative week by abdominal X-ray and renal ultrasound. The χ2 and one-way ANOVA tests were used for statistical analysis. A p value ≤0.05 was considered significant. RESULTS: The study included 115 patients (77 males) with a mean age of 50.2 (±13.3) years. Cases were classified according to GSS into 4 grades; there were 24 (20.9%) grade I, 48 (41.7%) grade II, 25 (21.7%) grade III, and 18 (15.7%) grade IV cases. There was a significant inverse correlation between GSS grade and SFR (p < 0.001). The rate of complications using the Clavien grading system were significantly higher in GSS grades III and IV (p = 0.002). So were the rates of blood transfusion, the need for >1 access tract, and the duration of hospitalization. CONCLUSION: GSS is a simple and easily reproducible system to classify the complexity of renal stones. In our setting, it also proved an excellent tool to predict SFR, perioperative complications, and associated ancillary procedures. Ultimately, it can help surgeons and, above all, patients to make a more informed decision about their surgery.

The Efficacy of Guy's Stone Score for Predicting the Stone-Free and Complication Rates in Children Treated by Percutaneous Nephrolithotomy.

Introduction: To determine the efficacy of Guy's stone score (GSS) for predicting stone-free and complication rates after percutaneous nephrolithotomy (PCNL) in children. Patients and Methods: A total of 197 renal units (RUs) in 173 children (≤17 years) who referred to our clinic were included in our study. RUs with stones were classified as four groups according to GSS. The results were designated as stone free or as having residual stones. Complications were evaluated according to GSS, the Satava, and modified Clavien grading system. All parameters were evaluated by using univariate and multivariate analysis. Results: The median age of patients was 6 years (1-17 years). Stone-free status was 77% and complication rate was 17%. Stone-free rate was established 89% for group 1, 78% for group 2, 75% for group 3, and 57% for group 4. There was a positive association between GSS and stone-free status (p = 0.02). No relationship was found between GSS and the complication rate (p = 0.42). In multivariate analysis, GSS was the only independent factor for predicting stone-free status. Conclusion: Current study revealed that GSS has a predictive ability for stone-free status; however, GSS is insufficient for predicting complications after pediatric PCNL. Even though, GSS does not fully reflect the characteristics of the pediatric population, we believe that it might provide useful insights for clinicians when recommending and discussing treatment options for children with urolithiasis.

[Do the nephrolithometry scoring systems predict the success of percutaneous nephrolithotomy. Comparison of 4 scores: The Guy's stone score, STONE Score, CROES nomogram and S-ReSC score]. / Les scores radiologiques peuvent-t-ils prédire le succès de la NLPC ? Étude comparative du Guy's stone score, du STONE score, du CROES nomogram, et du S-ReSc score.

INTRODUCTION: The aim of the study is to investigate the factors predictive of surgical outcomes of PCNL and to compare the predictability and accuracy of the Guy's stone score, STONE nephrolithometry, CROES nomogram and S-ReSC score. PATIENTS AND METHODS: We reviewed retrospectively the surgical outcomes recorded consecutively and imaging data of preoperative computed tomography scans of patients who underwent PCNL from 2013 to 2016. Patients with asymptomatic residual fragments<4mm were considered stone-free. Preoperative abdominopelvic computerized tomography images of the patients were reviewed and scored according The Guy's stone score, STONE nephrolithometry, CROES nomogram, S-ReSC score by one urologist. RESULTS: A total of 157 PCNLs were reviewed. The overall stone-free rate was 59% (92/157) with a complication rate of 22% (35/157). Stone Burden<542mm3 is significantly associated with stone-free rate (SFR) (P=0.001). On univariate analysis, all the scoring systems were identified as significant factors in terms of SFR. The Guy's Stone Score, the CROES score and the S-ReSC score were associated with complications (P<0.02). The multivariate logistic regression analysis showed that the CROES score was identified as a significant factor in terms of SFR and complications (P<0.01). The area under the receiver operating characteristic (ROC) curves for stone burden, the Guy's, STONE score, CROES core and S-ReSC scores showed good results (0.737/0.674/0.762/0.746/0.710) respectively. CONCLUSION: Although the four scoring systems were significantly associated with SFR, the STONE score was a significant predictive factor for SFR and complications after PCNL. LEVEL OF EVIDENCE: 3.

Increasing stone complexity does not affect fluoroscopy time in percutaneous nephrolithotomy.

BACKGROUND: The aim of this work was to assess whether stone complexity with the Guy's stone score (GSS) is associated with increased intraoperative fluoroscopy time. METHODS: We retrospectively reviewed records of 261 consecutive patients undergoing percutaneous nephrolithotomy between 2007 and 2015. Of these, 203 had both preoperative computed tomography for accurate staging and full intraoperative fluoroscopy and radiation dosimetry data were available. Stone complexity was assessed using GSS. A correlation between fluoroscopy time (FT) and GSS was assessed in a univariate and multivariate fashion, including parameters such as age, sex, body mass index (BMI), and number of accesses. RESULTS: The overall mean FT was 3.69 min [standard deviation (SD) 2.77]. The overall mean Guy's score was 2.5 (SD 1). There was a statistically significant correlation between operative time and FT (r = 0.34, p < 0.0001). There was a trend towards increasing operative time with increasing GSS (r = 0.12, p = 0.08), but there was no statistically significant correlation. There was no correlation between FT and GSS (r = 0.04, p = 0.55). On multivariable regression, accounting for sex, BMI, age, and singular versus multiple accesses, there was no significant correlation between stone complexity and FT (p = 0.893). CONCLUSIONS: In the setting of conscious efforts to reduce intraoperative radiation exposure, increasing stone complexity, as classified by GSS, did not correlate with FT on univariate or multivariate analysis. Thus, treatment of more complex stones may be undertaken without concern that there is an inevitable need for significantly increased fluoroscopy exposure to the patient or operating room staff.

Inter-observer variability amongst surgeons and radiologists in assessment of Guy's Stone Score and S.T.O.N.E. nephrolithometry score: A prospective evaluation.

OBJECTIVE: (a) To assess the inter-observer variability amongst surgeons performing percutaneous nephrolithotomy (PCNL) and radiologists for the Guy's Stone Score (GSS) and S.T.O.N.E. (stone size [S], tract length [T], obstruction [O], number of involved calyces [N], and essence or stone density [E]) nephrolithometry score; (b) To determine which scoring system of the two is better for predicting the stone-free rate (SFR) after PCNL. PATIENTS SUBJECTS AND METHODS: Patients undergoing PCNL between February 2016 and September 2016 were prospectively enrolled. Preoperative computed tomography was done in all patients. The GSS and S.T.O.N.E. nephrolithometry score were independently calculated by eight surgeons and four radiologists. The patients were operated on by one of the surgeons (all were consultants). The Fleiss' κ coefficient was used to assess agreement independently between the surgeons and radiologists. Receiver operating characteristic (ROC) curves were constructed for predicting the SFR using the average of the scores of the surgeons and radiologists separately. RESULTS: A total of 157 patients underwent PCNL. The SFR was 71.3% (112/157 patients). The Fleiss' κ scores ranged from 0.51 to 0.88 (overall 0.79) for the S.T.O.N.E. score and 0.53-0.91 for the GSS, suggesting moderate to very good agreement. The ROC curve for the S.T.O.N.E. nephrolithometry scores of surgeons (area under the curve [AUC] = 0.806) as well as the radiologists (AUC = 0.810) had a higher predictive value for the SFR than the GSS of the surgeons (AUC = 0.738) and the radiologists (AUC = 0.747). CONCLUSION: There is overall good agreement between surgeons and radiologists for both the GSS and S.T.O.N.E. nephrolithometry score. The S.T.O.N.E. score had a higher predictive value for the SFR than the GSS. ABBREVIATIONS: AUC: area under the curve; GSS: Guy's Stone Score; KUB: kidneys, ureters and bladder; NCCT: non-contrast CT; PCNL: Percutaneous nephrolithotomy; ROC: receiver operating characteristic; SFR: stone-free rate; S.T.O.N.E.: stone size [S], tract length [T], obstruction [O], number of involved calyces [N], and essence or stone density [E].

Predictability and Practicality of Image-Based Scoring Systems for Patient Assessment and Outcome Stratification During Percutaneous Nephrolithotomy: a Contemporary Update.

Preoperative nomograms offer systematic and quantitative methods to assess patient- and stone-related characteristics and their impact on successful treatment and potential risk of complication. Discrepancies in the correlation of perioperative variables to patient outcomes have led to the individual development, validation, and application of four independent scoring systems for the percutaneous nephrolithotomy: Guy's stone score, S.T.O.N.E. nephrolithometry, Clinical Research Office of the Endourology Society nomogram, and Seoul National University Renal Stone Complexity. The optimal nomogram should have high predictive ability, be practically integrated into clinical use, and be widely applicable to urinary stone disease. Herein, we seek to provide a contemporary evaluation of the advantages, disadvantages, and commonalities of each scoring system. While the current data is insufficient to conclude which scoring system is destined to become the gold standard, it is crucial that a nephrolithometric scoring system be incorporated into common practice to improve surgical planning, patient counseling, and outcome assessment.

How practical is the application of percutaneous nephrolithotomy scoring systems? Prospective study comparing Guy's Stone Score, S.T.O.N.E. score and the Clinical Research Office of the Endourological Society (CROES) nomogram.

OBJECTIVE: To prospectively compare the Guy's Stone Score (GSS), S.T.O.N.E. [stone size (S), tract length (T), obstruction (O), number of involved calices (N), and essence or stone density (E)] score and the Clinical Research Office of the Endourological Society (CROES) nephrolithometric nomogram to predict percutaneous nephrolithotomy (PCNL) success rate and assess the correlation with perioperative complications. PATIENTS AND METHODS: We prospectively evaluated all consecutive PCNL patients at our institute between 1 November 2013 and 31 May 2015. The above scoring systems were applied to preoperative non-contrast computed tomography and the practical difficulties in such applications were noted. Perioperative complications and the stone-free rate (SFR) were also recorded. Receiver operating characteristic curves were drawn and the areas under curves were compared and appropriate statistical analysis done. RESULTS: In all, 48 renal units were included in the study. The overall SFR was 62.2%. The presence of staghorn stones (ß = 27.285, 95% confidence interval 1.19-625.35; P = 0.039) was the only significant variable associated with the residual stones on multivariate analysis. Stone-free patients had significantly lower median GSS (2 vs 4) and S.T.O.N.E. scores (6 vs 10) and higher median CROES scores (83% vs 63%) (all P < 0.001) compared to residual-stone patients. All scoring systems were significantly associated with SFR (all P < 0.001). There was no significant difference in the areas under curves of the scoring systems (0.858, 0.923, and 0.931, respectively). Furthermore, all scoring systems had weak correlations with Clavien-Dindo classified complications (r = 0.29, P = 0.045; r = 0.40, P = 0.005 and r = -0.295, P = 0.04, respectively). We found no standardisation for the measurement of stone dimensions, tract length, Hounsfield units, and staghorn definition. CONCLUSIONS: All scoring systems equally predicted SFR and had a weak correlation with Clavien-Dindo complications. Standardisation is needed for the variables in which they have been found deficient.

Percutaneous nephrolithotomy; alarming variables for postoperative bleeding.

OBJECTIVES: To evaluate factors contributing to bleeding after percutaneous nephrolithotomy (PCNL) and ways of managing this complication, as bleeding is a serious sequela that requires prompt management. PATIENTS AND METHODS: The demographic and procedural data of 200 patients, who underwent unilateral PCNL during a 20-month period, were prospectively collected. Preoperative, operative, and postoperative details were recorded. The preoperative variables analysed included: age, sex, body mass index (BMI), the presence of hypertension, diabetes mellitus, serum creatinine, degree of hydronephrosis, previous ipsilateral open renal surgery, stone size and complexity. The operative variables analysed included: number of tracts, operative time, size of Amplatz sheath, type of anaesthesia, and complications such as calyceal and pelvic perforation. RESULTS: The variables of age, sex, BMI, diabetes, hypertension, and a preoperative creatinine level of >1.4 mg/dL had no significant effect on blood loss (all P > 0.05). However, the rate of bleeding was significantly higher (P â©½ 0.05) in patients who had a history of previous open renal surgery, intraoperative pelvicalyceal perforations, and Guy's Stone Score (GSS) grade 3 and 4 complex stones; however, absence of hydronephrosis, larger stone size, operative time (>83 min), more than one puncture, and size of the Amplatz sheath (26-30 F) did not maintain their significance in multivariate analysis. CONCLUSION: According to our present results stone complexity (GSS grade 3 and 4), history of ipsilateral renal stone surgery, and occurrence of intraoperative pelvicalyceal perforation are alarming variables for post-PCNL bleeding.

Pediatric Percutaneous Nephrolithotomy-Experience of a Tertiary Care Center.

OBJECTIVE: To present the experience of pediatric percutaneous nephrolithotomy (PCNL) of our center. MATERIALS AND METHODS: This study was conducted from 1995 to 2015, on patients <15 years of age having renal and upper ureteral stones who underwent PCNL. Stones were classified as per Guy's stone score (GSS). Standard bull's eye technique was used for subcostal puncture. To avoid supracostal puncture, puncture was done in full inspiration or by oblique tract. If these maneuvers failed, then supracostal puncture was done. Tract was dilated to 24F. RESULTS: Six hundred sixty PCNLs were performed on 639 patients. Puncture was subcostal in 87.6% cases with tract dilated as much as 24F. Pelvicaliceal system was most commonly accessed through middle calix (73.94%). Upper caliceal puncture (23.78%) was more frequently used in complete (82.35%) and partial staghorn (51%) stones. Two tracts were made in 16 (2.42%) cases, because of large stone burden. Average operative time was significantly longer in complex (45.43 minutes) compared to simple stones (29.39 minutes). Overall success rate was 94.39%, but it was significantly lower in partial (91.37%) and complete staghorn stones (82.35%). Complications were present in 21.66% cases and were classified according to Clavien grading. Majority of patients (97.9%) had minor complications (Clavien grade 1 & 2). On multivariate analysis, GSS ≥2, stone size >200 mm2, and multiple caliceal, partial, and complete staghorn stones were predictors of failure and complications. CONCLUSION: PCNL is a minimally invasive surgical technique for removal of renal and upper ureteral stones, which have low morbidity rate, high success rate, and short hospital stay. Although the uses of smaller instruments are on the rise, procedure can still be safely performed in children using adult instruments. Supracostal approach if done cautiously does not increase morbidity rate.

Prediction of stone-free status and complication rates after tubeless percutaneous nephrolithotomy: a comparative and retrospective study using three stone-scoring systems and preoperative parameters.

PURPOSE: To investigate the factors predictive of surgical outcomes of tubeless percutaneous nephrolithotomy (TPCNL) and to compare the predictability and accuracy of the Guy's stone score, S.T.O.N.E. nephrolithometry, and CROES nomogram. PATIENTS AND METHODS: We reviewed retrospectively the surgical outcomes recorded consecutively and imaging data of preoperative computed tomography scans of 141 patients who had undergone TPCNL from June 2012 to October 2015. Guy's, S.T.O.N.E., and CROES stone-scoring systems (SSSs) and other prognostic factors were assessed using univariate and multivariate statistical analyses. RESULTS: The initial stone-free and complication rates after TPCNL were 78.7 (111/141) and 17.0 % (24/141). On univariate analysis, all three scoring systems were identified as significant factors in terms of stone-free rate (SFR). The multivariate logistic regression analysis showed that the Guy's stone score and stone burden ≥385 mm2 had significant correlations with stone-free status [odds ratios (OR) = 3.220, p = 0.001 and OR = 6.451, p = 0.002, respectively]. Guy's stone score (OR = 1.879, p = 0.013) was an independent risk factor for the development of complications. The area under the receiver operating characteristic (ROC) curves for the Guy's, S.T.O.N.E., and CROES SSSs and stone burden showed good results (0.821, 0.816, 0.820, and 0.800, respectively). Pairwise comparison of ROC curves showed that there was no significant difference between each final score and stone burden. CONCLUSIONS: Of the three scoring systems, Guy's stone score was the only significant predictive factor for SFR and complication rates after TPCNL in the multivariate logistic regression analysis. Stone burden was significantly associated with a postoperative stone-free status (SFS).

Evaluation of CROES Nephrolithometry Nomogram as a Preoperative Predictive System for Percutaneous Nephrolithotomy Outcomes.

PURPOSE: Scoring systems have been devised to predict outcomes of percutaneous nephrolithotomy (PCNL). CROES nephrolithometry nomogram (CNN) is the latest tool devised to predict stone-free rate (SFR). We aim to compare predictive accuracy of CNN against Guy stone score (GSS) for SFR and postoperative outcomes. MATERIALS AND METHODS: Between January 2013 and December 2015, 313 patients undergoing PCNL were analyzed for predictive accuracy of GSS, CNN, and stone burden (SB) for SFR, complications, operation time (OT), and length of hospitalization (LOH). We further stratified patients into risk groups based on CNN and GSS. RESULTS: Mean ± standard deviation (SD) SB was 298.8 ± 235.75 mm2. SB, GSS, and CNN (area under curve [AUC]: 0.662, 0.660, 0.673) were found to be predictors of SFR. However, predictability for complications was not as good (AUC: SB 0.583, GSS 0.554, CNN 0.580). Single implicated calix (Adj. OR 3.644; p = 0.027), absence of staghorn calculus (Adj. OR 3.091; p = 0.044), single stone (Adj. OR 3.855; p = 0.002), and single puncture (Adj. OR 2.309; p = 0.048) significantly predicted SFR on multivariate analysis. Charlson comorbidity index (CCI; p = 0.020) and staghorn calculus (p = 0.002) were independent predictors for complications on linear regression. SB and GSS independently predicted OT on multivariate analysis. SB and complications significantly predicted LOH, while GSS and CNN did not predict LOH. CNN offered better risk stratification for residual stones than GSS. CONCLUSION: CNN and GSS have good preoperative predictive accuracy for SFR. Number of implicated calices may affect SFR, and CCI affects complications. Studies should incorporate these factors in scoring systems and assess if predictability of PCNL outcomes improves.

Percutaneous nephrolithotomy for staghorn stones: Which nomogram can better predict postoperative outcomes?

PURPOSE: To identify independent predictors for postoperative stone-free status after percutaneous nephrolithotomy (PCNL) for staghorn stones and to compare Guy's, CROES and STONE nomograms regarding their predictive ability and accuracy specifically for staghorn stones. METHODS: Data of 286 patients who underwent PCNL in our department were collected and analyzed. Several parameters, including the three nomograms, were analyzed to reveal independent predictors for postoperative stone-free status. The area under the curve was used to assess the predictive ability of the independent predictors. RESULTS: A total of 73 staghorn calculi were identified with mean stone burden of 1253.5 mm(2). Mean Guy's, CROES and STONE score was 3.34, 125.8 and 9.95, respectively. Postoperative stone-free rate was 65.8 %. In univariate analysis, all three nomograms were significantly associated with stone-free status. However, STONE was the only significant independent predictor in multivariate analysis. STONE also revealed the highest predictive accuracy compared to Guy's and CROES nomogram. CONCLUSIONS: STONE nephrolithometry was found to be the only predictor for stone-free rate after PCNL for staghorn stones compared to Guy's and CROES nomograms.

Prospective evaluation of complications using the modified Clavien grading system, and of success rates of percutaneous nephrolithotomy using Guy's Stone Score: A single-center experience.

INTRODUCTION AND OBJECTIVES: To prospectively document the perioperative complications of percutaneous nephrolithotomy (PCNL) using the modified Clavien grading system. Evaluation of complications and clearance rates according to stone complexity using the validated Guy's Stone Score (GSS) was also done. MATERIALS AND METHODS: A total of 221 renal units underwent 278 PCNL procedures at a urology resident training center between September 2010 and September 2011 and data were recorded prospectively in our registry. Patients with co-morbidities like diabetes, renal failure, hypertension and cardiopulmonary diseases were excluded. Stone complexity was classified according to the GSS while peri-operative complications were recorded using the modified Clavien grading system. RESULTS: Two hundred and forty-five complications were encountered in 278 PCNL procedures involving 116 renal units (41.72%). Complications of Grades 1, 2, 3a, 3b, 4a, 4b and 5 were seen in 52 (18.7%), 122 (43.8%), 42 (15.1%), 18 (6.4%), 6 (2.1%), 4 (1.4%) and 1 (0.3%) renal units respectively. There were 68, 98, 50 and 5 renal units in GSS I, II, III and IV groups, respectively. All grades of complications were more common in GSS III and IV (P<0.05). For GSS I, II, III and IV 100%, 74%, 56% and 0% of renal units, respectively, were stone-free after one session and 0%, 24%, 44% and 60% respectively needed two sessions to be stone-free. CONCLUSION: Although the complication rates were higher most were of low grade and self-limiting. Complications were significantly more common with higher GSS and the GSS effectively predicted stone-free rates.