Stesura Seveso Archivio Italiano di Urologia e Andrologia 2024; 96(4):13295 1 ORIGINAL PAPER INTRODUCTION Percutaneous nephrolithotomy (PCNL) is the gold standard procedure to treat relatively large renal stones (> 2 cm) with a high success rate but still with significant morbidity despite technical advances. There is no consensus on an ideal predictive model of morbidity outcomes following PCNL. Available predictive tools aim at assessing the kidney stone complexity to predict the stone-free rate. They include the Guy’s Stone Score, the CROES nomogram, S.T.O.N.E. nephrolithometry, Seoul National University Renal Stone Complexity (S-ReSC) score, and the Simple Stone Score (SSS) (1-5). In our opinion, the risk of surgical complications is an important variable that should guide clinical decision-mak- ing. In comparative studies, none of the available scoring systems was fully satisfactory in predicting surgical compli- cations (6). Considering the deficient literature in assessing post-PCNL morbidity, this study was conducted to develop a widely applicable, simple disease stratification tool that will greatly improve patient counseling, surgical planning, evaluation of outcomes, and academic reporting. METHODS Patient data A total of 631 patients who underwent PCNL at the col- laborating centers were retrospectively analyzed. The pro- Introduction: A model to predict the risk of surgical complications following percuta- neous nephrolithotomy (PCNL) could be a useful tool to guide clinical decision-making. The aim of this study was to develop a simple and widely applicable stratification tool to be used for patient counseling, surgical planning, evaluation of outcomes, and academic reporting. Methods: Data of patients who underwent PCNL were retrieved from the database of the collaborating centers including demo- graphics of patients, characteristics of their stones and urinary tracts, and perioperative data. The primary outcome was the development of postoperative complications. Data were random- ly split into a training dataset (85%) and a validation dataset (15%). A univariate and multivariate logistic regression analysis of the training dataset was performed to identify independent predictors of postoperative complications. Model variables were used to construct a nomogram that was internally validated on the testing dataset by measuring calibration, discrimination, and plotting the decision curve. Results: Six hundred thirty one patients (245 Males) with a median (IQR) age of 49 (37-56) years were included. Post-oper- ative complications occurred in 147 (23.3%) patients. Significant predictors of complications included preoperative urine culture (p < 0.001), largest stone diameter (p = 0.02), and intraopera- tive blood loss (p = 0.002). A nomogram was developed from the predictors and applied to the validation dataset showing an area under the curve (95%CI) of 66.4% (52.2;80.6). Conclusions: This new scoring system emphasized patient char- acteristics and operative details rather than stone characters to predict the morbidity of PCNL. Furthermore, it should facilitate risk adjustment, enabling physicians to better define the nephrolithiasis disease continuum and identify patients who should be referred to tertiary care centers. Development and internal validation of El-Shazly-Buchholz’s nomogram to predict postoperative complications after PCNL: A multicenter study Rawa Bapir 1, 2, Kamran Bhatti 3, Mohamed El-Shazly 4, Juan Antonio Galan 5, Ahmed M. Harraz 6, 7, Sarwar Noori Mahmood 8, Renato N. Pedro 9, Pablo Vargas 10, Athanasios Papatsoris 11, 12, Alberto Trinchieri 12, Noor Buchholz 12 1 Department of Urology, Sulaymaniyah Surgical Teaching Hospital, Sulaymaniyah, Iraq; 2 Smart Health Tower, Madam Mitterrand Street, Sulaymaniyah, Iraq; 3 HMC Medical Corporation, Al Khor, Qatar; 4 Menoufia University, Shebin Elkom 32714, Egypt; 5 Department of Urology, Dr. Balmis General University Hospital, Alicante Institute for Health and Biomedical Research (ISABIAL), Alicante, Spain; 6 Mansoura University Urology and Nephrology Center, Mansoura, Egypt; 7 Farwaniya Hospital and Sabah Al Ahmad Urology Center, Kuwait City, Kuwait; 8 Department of Surgery, College of Medicine, University of Sulaymaniyah, Sulaymaniyah, Iraq; 9 Division of Urology, Faculdade de Medicina São Leopoldo Mandic de Campinas, Sao Paulo, Brazil; 10 Marina Baixa Hospital. La Vila Joiosa. Alicante. Spain; 11 2nd Department of Urology, School of Medicine, Sismanoglio Hospital, National and Kapodistrian University of Athens; 12 U-merge Scientific Office. DOI: 10.4081/aiua.2024.13295 Summary KEY WORDS: Percutaneous nephrolithotomy; Complications; Urine culture; Stone diameter; Intraoperative blood loss. Submitted 24 October 2024; Accepted 28 October 2024 Archivio Italiano di Urologia e Andrologia 2024; 96(4):13295 R. Bapir, K. Bhatti, M. El-Shazly, et al. 2 cedures used in this study adhere to the tenets of the Declaration of Helsinki (as revised in 2013). Approval was obtained from the Research Ethics Committees of Medical Research Center HMC (MRC-01-20-385). Because of its retrospective nature, the consent was waived from the par- ticipants. All the information collected during the research project remained confidential to the extent required and provided by law. Patient data were anonymized, coded, and kept by the principal investigator. The preoperative clinical data included age, gender, body mass index (BMI), recurrent stone status, previous renal surgery in the ipsilateral kidney, associated comorbidities, the American Society of Anesthesia (ASA) score, preopera- tive urine culture, and diagnostic imaging (modality). Stone characteristics were the stone diameter, burden, density (Hounsfield Unit), and the number of involved calyces. Intraoperative documented data included PCNL position, operative time, number of tracts, size of the tract, intra- operative blood loss (Hb loss > 2 gr/dl), pus on the punc- ture, residual fragments size and number, exit strategy, combination with retrograde intrarenal surgery (RIRS), and the caseload of surgeon per year. Postoperatively, collected data were fever, urine culture, sepsis, bleeding, postoperative transfusion, length of hospital stay, and stone-free status/residual fragments. Study outcome The primary outcome was the development of postoper- ative complications by Clavien-Dindo system (7). A sec- ondary outcome was the development of postoperative infectious complications. Statistical analysis The data were randomly split into a training dataset (85%) and a validation dataset (15%). In the training dataset, a univariate and multivariate logistic regression analysis was performed to identify independent predic- tors of the occurrence of any postoperative complication. Statistical significance was determined using the Chi- square or Fischer's exact tests for categorical variables whenever appropriate. Mann-Whitney U or Student t- tests were used for non-parametric and parametric vari- ables, respectively. Model variables were used to con- struct a nomogram. The nomogram was internally vali- dated by measuring calibration, discrimination, and plot- ting the decision curve. A calibration plot was generated to identify how much predicted nomogram probabilities match the actual post-operative complications values. The discrimination was evaluated by calculating the area under the curve (desired when more than 50%). Decision curve analysis reveals the net benefit of using the model to detect postoperative complications. The decision curve compares the ability of the nomogram to distinguish the occurrence or absence of complications according to a range of threshold probabilities. If the decision curve shows a higher net benefit, it is clinically beneficial. Statistical analysis was performed using R programming language version 4.1.2. with p-value less than 0.05 was considered statistically significant. RESULTS Patients’ demographics A total of 631 patients with a median (IQR) age of 49 (37:56) years were included. Female patients constituted 38.83% while obese patients (> 30 BMI) accounted for 43.26%. Four institutions contributed to the current study [J: 100 (15.85%), M: 99 (15.69%), R: 332 (52.61%), and U: 100 (15.85%) patients]. Postoperative complications occurred in 147 (23.3%) patients. After random splitting, there was no significant difference between both groups. The difference between both groups is shown in Table 1. Table 1. Comparison between training and validating datasets for patients who underwent percutaneous nephrolithotomy in 4 institutions. Parameter Train Validate p-value Institutions 0.3 J 79 (14.74%) 21 (22.11%) M 83 (15.49%) 16 (16.84%) R 287 (53.54%) 45 (47.37%) U 87 (16.23%) 13 (13.68%) Age median (IQR) 50 (38:56) 47 (34.5:55) 0.09 Gender 0.6 Female 205 (38.25%) 40 (42.11%) Male 331 (61.75%) 55 (57.89%) BMI, median (IQR) 29.31(26.1:32.1) 28.5 (26.7:32.8) 0.9 Obesity 0.2 Non-obese 298 (55.6%) 60 (63.16%) Obese 238 (44.4%) 35 (36.84%) Recurrent one 0.7 No 375 (69.96%) 64 (67.37%) Yes 161 (30.04%) 31 (32.63%) Previous one surgery 0.6 No 380 (70.9%) 64 (67.37%) Yes 156 (29.1%) 31 (32.63%) Diabetes Mellitus 0.7 No 474 (88.43%) 86 (90.53%) Yes 62 (11.57%) 9 (9.47%) Hypertension 0.3 No 444 (82.84%) 83 (87.37%) Yes 92 (17.16%) 12 (12.63%) ASA score 0.5 I 310 (57.84%) 54 (56.84%) II 194 (36.19%) 38 (40%) III 32 (5.97%) 3 (3.16%) Preoperative urine culture 0.7 Negative 490 (91.42%) 85 (89.47%) Positive 46 (8.58%) 10 (10.53%) LSD, mm, median (IQR) 30 (20:41) 32 (25:40) 0.2 Number of involved calyces 0.5 0 103 (19.22%) 16 (16.84%) 1 196 (36.57%) 31 (32.63%) 2 102 (19.03%) 24 (25.26%) 3 135 (25.19%) 24 (25.26%) HU, mean (SD) 1037 (312.9) 971.2 (325.5) 0.07 Sheath size 0.1 Mini 164 (30.6%) 21 (22.11%) Standard 372 (69.4%) 74 (77.89%) OR time, min, median (IQR) 70 (35:120) 80 (45:130) 0.07 Intraoperative blood loss 0.5 No 494 (92.16%) 90 (94.74%) Yes 42 (7.84%) 5 (5.26%) Residual fragment 0.1 No 424 (79.1%) 68 (71.58%) Yes 112 (20.9%) 27 (28.42%) LOS, days, median (IQR) 1 (1:2) 1 (1:3) 0.2 Archivio Italiano di Urologia e Andrologia 2024; 96(4):13295 3 Development and internal validation of El-Shazly-Buchholz’s nomogram to predict postoperative complications after PCNL... Predictors of complications in the training dataset Significant variables include preoperative urine culture [positive: 24 (5.78%) versus 22 (18.18%), p < 0.001], median (IQR) largest stone diameter [30 (20:40) versus 35 (22:48), p = 0.02], intraoperative blood loss [24 (5.78%) versus 18 (14.88%), p = 0.002]. Data are dis- played in Table 2. On multivariate logistic regression analysis, independent predictors were intra-operative blood loss [odds ratio (OR) and 95% confidence interval (CI): 2.5 (1.2:4.9), p = 0.007], preoperative urine culture [OR (95%CI): 3.2 (1.6:6), p < 0.001] (Table 3). Nomogram development and validation A nomogram was developed from the predictors and is dis- played in Figure 1. The nomogram is applied to the vali- dation dataset. The area under the curve (95%CI) was 66.4 (52.2; 80.6). Regarding calibration, the nomogram's pre- dicted probabilities slightly overestimated the post-opera- tive complications' actual occurrence. The Calibration plot is displayed in Figure 2A. The decision curve shows a high- er net benefit of the model in a wide range of thresholds (25%-75%). Therefore, the model is performing better in this range of thresholds than if treatment of complications is considered in all patients or in none of the patients. Results are displayed in Figure 2B. Table 2. Univariate and logistic regression analysis for predictors of post-PCNL complications. Parameter Complications P-value No Yes Age median (IQR) 49 (38:56) 51 (37:62) 0.2 Gender 1 Female 158 (38.07%) 47 (38.84%) Male 257 (61.93%) 74 (61.16%) BMI median (IQR) 29.3 (26.1:32.1) 29.3 (25.3:31.9) 0.5 Recurrent stone 0.5 No 294 (70.84%) 81 (66.94%) Yes 121 (29.16%) 40 (33.06%) Diabetes Mellitus 0.3 No 363 (87.47%) 111 (91.74%) Yes 52 (12.53%) 10 (8.26%) Hypertension 0.05 No 336 (80.96%) 108 (89.26%) Yes 79 (19.04%) 13 (10.74%) Preoperative urine culture < 0.001 Negative 391 (94.22%) 99 (81.82%) UTI 24 (5.78%) 22 (18.18%) LSD, mm, median (IQR) 30 (20:40) 35 (22:48) 0.02 Number of involved calyces 0.07 0 89 (21.45%) 14 (11.57%) 1 150 (36.14%) 46 (38.02%) 2 73 (17.59%) 29 (23.97%) 3 103 (24.82%) 32 (26.45%) HU, mean (SD) 1038.7 (319.3) 1031(291) 0.8 Sheath size 1 Mini 127 (30.6%) 37 (30.58%) Standard 288 (69.4%) 84 (69.42%) Intraoperative blood loss 0.002 No 391 (94.22%) 103 (85.12%) Yes 24 (5.78%) 18 (14.88%) No. of punctures 0.5 Single 362 (87.23%) 102 (84.3%) Multiple 53 (12.77%) 19 (15.7%) RF number, median (IQR) 1 (1:2) 1 (1:2) 0.3 Drainage 0.08 JJ 11 (2.65%) 9 (7.44%) JJ and PCN 304 (73.25%) 81 (66.94%) PCN 60 (14.46%) 16 (13.22%) Tubeless 40 (9.64%) 15 (12.4%) BMI: Body mass index; LSD: Largest stone diameter; HU: Hounsfield units; OR: Operation; LOS: Length of stay. * Mode of drainage after the procedures. Table 3. Multivariate logistic regression analysis for predictors of postoperative complications after percutaneous nephrolithotomy. B OR (95% CI) p-value (Intercept) -1.807 0.164 (0.09:0.2) < 0.001 Intraoperative blood loss (yes) 0.925 2.521 (1.2:4.9) 0.007 Preoperative urine culture (positive) 1.168 3.215 (1.6:6.1) < 0.001 Largest stone diameter, mm 0.01 1.01 (0.9:1.02) 0.1 B: Regression coefficient; OR: Odds ratio; CI: Confidence interval. Figure 1. Nomogram for the evaluation of the risk of complications after PCNL. Parameter Train Validate P-value Stone free status 0.2 No 106 (19.78%) 25 (26.32%) Yes 430 (80.22%) 70 (73.68%) No. of punctures 0.07 Single 464 (86.57%) 75 (78.95%) Multiple 72 (13.43%) 20 (21.05%) RF number, median (IQR) 1 (1:2) 1 (1:2) 0.9 PCN only * 0.3 F No 21 (4.36%) 1 (1.32%) Yes 461 (95.64%) 75 (98.68%) JJ only * 0.6 Yes 405 (84.02%) 66 (86.84%) No 77 (15.98%) 10 (13.16%) PCN and JJ * 0.3 No 97 (20.12%) 11 (14.47%) Yes 385 (79.88%) 65 (85.53%) Postoperative Complications 0.4 No 415 (77.43%) 69 (72.63%) Yes 121 (22.57%) 26 (27.37%) Infectious Complications 0.3 No 432 (80.6%) 72 (75.79%) Yes 104 (19.4%) 23 (24.21%) BMI: Body mass index; ASA: American society of anesthesiology; LSD: Largest stone diameter; HU: Hounsfield units; OR: Operation; LOS: Length of stay. * Mode of drainage after the procedures. Archivio Italiano di Urologia e Andrologia 2024; 96(4):13295 R. Bapir, K. Bhatti, M. El-Shazly, et al. 4 DISCUSSION Literature exhibits multiple stone scoring systems for evaluating outcomes of percutaneous nephrolithotomy including the Guy’s stone score, the Clinical Research Office of the Endourological Society (CROES) nomogram, the S.T.O.N.E. score, and the S-ReSC score (1-5). The pivotal variables in all the scoring systems are stone loca- tion, stone number, and the presence of staghorn calculi. The Guy’s stone score stratifies patients into four grades, where grade I indicates a solitary stone with simple anato- my (mid-lower pole or renal pelvis), grade II a solitary stone in the upper pole or multiple stones with simple anatomy or a solitary stone with abnormal anatomy, grade III multiple stones with abnormal anatomy or stones in a calyceal diverticulum or partial staghorn stone, and grade IV staghorn stone or any stone in a patient with spina bifida or spinal injury. The S.T.O.N.E. score classifies patients into low-, moderate-, and high- risk groups according to stone size (S), tract length (T), obstruction (O), number of involved calyces (N), and essence (E) (composition or stone density). The CROES nomogram grades risk across a continuous scale consid- ering the stone burden, location, number, and surgical volume. The S-ReSC scoring system subdivides the pelvi- caliceal system in nine locations and the score is the cumulative sum of the locations involved by the stone. Several studies evaluated the efficacy of these stone-scor- ing systems in predicting the stone-free status and the incidence of complications after percutaneous nephrolithotomy. A systematic review (6) of ten studies (8-17) with metanalysis compared the efficacy of the stone scoring systems in predicting stone-free rate after PCNL most of them confirming their equal predictive efficacy of the stone-free rate. Stone free status was negatively related to Guy’s (WMD = -0.64, p < 0.0001) and S.T.O.N.E. score (WMD = -1.23, p < 0.0001) and positively to the score of CROES nomo- gram (WMD = 29.48, p = 0.003). No significant differ- ence between the three stone scoring nomogram was found at comparison of area under curves (AUC) of pre- dicting stone free rate. A secondary outcome of the systematic review of Jiang et al. (6) was the comparison of the efficacy of the stone score systems in predicting complications after PCNL. Tailly et al. (16) and Sfoungaristos et al. (15) did not find correlation between stone scores and complication rates. Similarly, Noureldin et al. (14) and Kocaaslan et al. (12) observed no significant correlation of Guy score and S.T.O.N.E. score with complications after PCNL. Only Bozkurt et al. (8) observed a correlation of Guy’s score and the CROES nomogram with complication rates after PCNL. In addi- tion, Choi et al. (10) compared the predictability of the out- comes of tubeless PCNL using the Guy score, CROES nomogram, and S.T.O.N.E. score showing that only the Guy score was able to predict the complication rate after PCNL. The metanalysis showed that only the Guy’s score was able to predict complications after PCNL (WMD = - 0.29, 95% CI: -0.57 to -0.02, p = 0.03). A systematic review (18) specifically focused on the corre- lation between stone scoring systems and postoperative complications after PCNL in adult patients adding six stud- ies (19-24) to the 5 studies (9, 10, 13, 16, 17) previously considered by the systematic review of Jiang et al. (6). A sig- nificant correlation with complications was obtained with Guy’s stone score in 6 out 9 studies, with S.T.O.N.E. nephrolithometry score in 4 out 11 studies, with CROES score in 3 out 9 studies and with S-ReSC score in one of two studies, respectively. Other studies (16, 19-21) showed no correlation between nomograms and post-sur- gical complications graded using the Clavien-Dindo (CD) classification system modified for PCNL (8). Biswas et al. (22) found significative correlations between GSS, S.T.O.N.E. nephrolithometry score, and CROES score with post-operative complications including EBL. Labadie et al. (13) reported no significant correlation at logistic regres- sion analysis of GSS, S.T.O.N.E. nephrolithometry score and CROES score with most post-operative complications, although GSS and S.T.O.N.E. nephrolithometry were cor- Figure 2. Calibration plot (A) and Range of Threshold. Archivio Italiano di Urologia e Andrologia 2024; 96(4):13295 5 Development and internal validation of El-Shazly-Buchholz’s nomogram to predict postoperative complications after PCNL... related with EBL. Choi et al. (9) found a correlation between GSS and post-operative complications, while S.T.O.N.E. nephrolithometry score and CROES score were not corre- lated. Similar results were obtained by the same authors in a cohort of tubeless PCNL (10). Al Adl et al. (23) evaluated the correlation between all four nomograms and complica- tions observing a modest correlation of S.T.O.N.E. nephrolithometry score, GSS, S-ReSC score, and CROES score with complications according to CD, although only GSS, S-ReSC score and CROES score correlated with EBL. Khan et al. (24) reported significant correlation between both S.T.O.N.E. nephrolithometry score and GSS with overall complication rates at multivariate analysis. Overall results demonstrated that stone morphology, as accurately described by the stone scoring systems, seemed to be not sufficient by itself to accurately predict the risk of compli- cations after PCNL. Our nomogram adds to a measure of stone size, as stone diameter, other two easily obtained measures as positivi- ty of preoperative urine culture and intraoperative blood loss. Preoperative urine culture is mandatory before PCNL although it was well demonstrated that a negative midstream urine culture cannot exclude the presence of infection in the stone or the urinary tract upstream of the stone (25). A systematic review of 19 studies demonstrated that pos- itivity of stone culture was associated with higher odds of developing a Systemic Inflammatory Response Syndrome (SIRS) after PCNL in comparison with preoperative mid- stream urine culture (PMUC), although the odds of devel- oping sepsis were not significantly different between pos- itivity of stone culture or PMUC (26). In another study, high procalcitonin (PCT) values, IL-6 (> 264 pg/ml), SIRS score (> 2.5), National Early Warning Score (NEWS) (> 2.5), quick Sequential Organ Failure Assessment (qSOFA) (> 0.50) and surgical time were inde- pendent risk factors for septic shock (27). Finally, at mul- tivariate analysis, renal pelvic pressure ≥ 30 mmHg dur- ing PCNL procedure was included among the more rele- vant risk factors for urosepsis together with operative time, bladder urine culture and hydronephrosis (28). Intraoperative blood loss is a parameter that can be only obtained at the end of the procedure therefore it cannot be used in the choice and the planning of the treatment although it can be useful to identify those patients that are at higher risk of complications requiring a strict follow- up for prevention and early treatment of complication. The strength of this study is the homogeneity of the series that was analyzed, which comes from only 4 centres that contributed at least 100 cases each. The number of cases studied is relatively high although for the prediction of less frequent and more serious complications it could be even too small. Furthermore, the retrospective design constitutes another limitation. Finally, for the prediction of infectious complications, some microbiological parameters were not available (cul- ture of the pelvic urine and of the stone) as well as some laboratory tests (C-reactive protein, procalcitonin) and symptomatic scores predictive of the systemic inflamma- tory response or sepsis. For these reasons, the efficacy of the nomogram will have to be confirmed by prospective studies of larger series. CONCLUSIONS This new scoring system (the El-Shazly-Buchholz’s nomo- gram) emphasized on patient characteristics and opera- tive details rather than stone features as in previous scores. It should allow reliable and accurate comparisons of treatment efficacy and quality of surgical care by pre- dicting the morbidity of PCNL. Furthermore, it should facilitate risk adjustment, enabling physicians to better define the nephrolithiasis disease continuum and identify patients who should be referred to tertiary care centers. ACKNOWLEDGMENTS This study was designed by Noor Buchholz who organized its initial phase and contributed an important surgical case series. After he passed away on February 13, 2024, his col- laborators and friends wanted to complete his work so that the memory of his enthusiastic activity in the study and treatment of kidney stones is maintained over time. REFERENCES 1. Thomas K, Smith NC, Hegarty N, Glass JM. The Guy's stone score—grading the complexity of percutaneous nephrolithotomy pro- cedures. Urology. 2011; 78:277-81. 2. Okhunov Z, Friedlander JI, George AK, et al. S.T.O.N.E. nephrolithometry: novel surgical classification system for kidney cal- culi. Urology. 2013; 81:1154-9. 3. Smith A, Averch TD, Shahrour K, et al. A nephrolithometric nomogram to predict treatment success of percutaneous nephrolitho- tomy. J Urol. 2013; 190:149-56. 4. Jeong CW, Jung JW, Cha WH, et al. Seoul National University renal stone complexity score for predicting stone-free rate after per- cutaneous nephrolithotomy. PLoS One 2013; 8:e65888 5. Harraz AM, El-Nahas AR, Nabeeh MA, et al. Development and validation of a simple stone score to estimate the probability of resid- ual stones prior to percutaneous nephrolithotomy. Minerva Urol Nephrol. 2021; 73:525-531. 6. Jiang K, Sun F, Zhu J, et al. Evaluation of three stone-scoring sys- tems for predicting SFR and complications after percutaneous nephrolithotomy: a systematic review and meta-analysis. BMC Urol. 2019; 19:57. 7. de la Rosette JJ, Opondo D, Daels FP, et al. Categorisation of com- plications and validation of the Clavien score for percutaneous nephrolithotomy. Eur Urol. 2012; 62:246-55. 8. Bozkurt IH, Aydogdu O, Yonguc T, et al. Comparison of guy and clinical research Office of the Endourological Society Nephrolithometry Scoring Systems for predicting stone-free status and complication rates after percutaneous Nephrolithotomy: a single centerstudy with 437 cases. J Endourol. 2015; 29:1006-10. 9. Choi SW, BaeWJ, Ha US, et al. Prognostic impact of stone-scoring systems after percutaneous Nephrolithotomy for staghorn calculi: a single Center's experience over 10 years. J Endourol. 2016; 30:975- 81. 10. Choi SW, Bae WJ, Ha US, et al. 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. World J Urol. 2017; 35:449-457. 11. Jaipuria J, Suryavanshi M, Sen TK. Comparative testing of reliability and audit utility of ordinal objective calculus complexity Archivio Italiano di Urologia e Andrologia 2024; 96(4):13295 R. Bapir, K. Bhatti, M. El-Shazly, et al. 6 scores. Can we make an informed choice yet? BJU Int. 2016; 118:958-68. 12. Kocaaslan R, Tepeler A, Buldu I, et al. Do the urolithiasis scor- ing systemspredict the success of percutaneous nephrolithotomy in cases with anatomical abnormalities? Urolithiasis. 2016; 45:305-10. 13. Labadie K, Okhunov Z, Akhavein A, et al. Evaluation and com- parison of urolithiasis scoring systems used in percutaneous kidney stone surgery. J Urol. 2015; 193:154-9. 14. Noureldin YA, Elkoushy MA, Andonian S. Which is better? Guy's versus S.T.O.N.E. nephrolithometry scoring systems in predicting stone-free status postpercutaneous nephrolithotomy. World J Urol. 2015; 33:1821-5. 15. Sfoungaristos S, Gofrit ON, Pode D, et al. Percutaneous nephrolithotomy for staghorn stones: which nomogram can better predict postoperative outcomes? World J Urol. 2016; 34:1163-8. 16. Tailly TO, Okhunov Z, Nadeau BR, et al. Multicenter external validation and comparison of stone scoring Systems in Predicting Outcomes after Percutaneous Nephrolithotomy. J Endourol. 2016; 30:594-601. 17. Yarimoglu S, Polat S, Bozkurt IH, et al. Comparison of S.T.O.N.E and CROES nephrolithometry scoring systems for pre- dicting stone-free status and complication rates after percutaneous nephrolithotomy: a single center study with 262 cases. Urolithiasis. 2017; 45:489-494. 18. Mazzon G, Choong S, Celia A. Stone-scoring systems for pre- dicting complications in percutaneous nephrolithotomy: A systematic review of the literature. Asian J Urol. 2023; 10:226-238. 19. Ozgor F, Yanaral F, Savun M, et al. Comparison of STONE, CROES and Guy’s nephrolithometry scoring systems for predicting stone-free status and complication rates after percutaneous nephrolithotomy in obese patients. Urolithiasis 2018; 46:471-7. 20. Farhan M, Nazim SM, Salam B, Ather MH. Prospective evalua- tion of outcome of percutaneous nephrolithotomy using the ‘STONE’ nephrolithometry score: a single-centre experience. Arab J Urol 2015; 13:264-9. 21. Yarimoglu S, Bozkurt IH, Aydogdu O, et al. External validation and comparisons of the scoring systems for predicting percutaneous nephrolithotomy outcomes: a single center experience with 506 cases. J Laparoendosc Adv Surg Tech 2017; 27:1284-9. 22. Biswas K, Gupta SK, Tak GR, et al. Comparison of STONE score, Guy’s stone score and Clinical Research Office of the Endourological Society (CROES) score as predictive tools for percu- taneous nephrolithotomy outcome: a prospective study. BJU Int 2020; 126:494-501. 23. Al Adl AM, Mohey A, Abdel Aal A, et al. Percutaneous nephrolithotomy outcomes based on S.T.O.N.E., GUY, CROES, and S-ReSC scoring systems: the first prospective study. J Endourol 2020; 34:1223e8. 24. Khan N, Nazim SM, Farhan M, et al. Validation of S.T.O.N.E nephrolithometry and Guy’s stone score for predicting surgical outcome after percutaneous nephrolithotomy. Urol Ann 2020; 12:324e30. 25. Mariappan P, Smith G, Bariol SV, et al. Stone and pelvic urine culture and sensitivity are better than bladder urine as predictors of urosepsis following percutaneous nephrolithotomy: a prospective clin- ical study. J Urol. 2005; 173:1610-4. 26. Li Y, Xie L, Liu C. Prediction of systemic inflammatory response syndrome and urosepsis after percutaneous nephrolithotomy by urine culture, stone culture, and renal pelvis urine culture: Systematic review and meta-analysis. Heliyon 2024; 10:e33155. 27. Yuxin Liu Y, Sun Q, Long H, et al. The value of IL-6, PCT, qSOFA, NEWS, and SIRS to predict septic shock after Percutaneous nephrolithotomy. BMC Urology 2024; 24:116. 28. Haoxiang Xu H, Wang K, Cao Z, et al. Nomogram including renal pelvic pressure to predict the occurrence of urosepsis following percutaneous nephrolithotomy: a dual center retrospective study of 1,448 patients. Transl Androl Urol 2024; 13:667-678. Correspondence Rawa Bapir, MD dr.rawa@yahoo.com Department of Urology, Sulaymaniyah Surgical Teaching Hospital, Sulaymaniyah, Iraq Smart Health Tower, Madam Mitterrand Street, Sulaymaniyah, Iraq Kamran Bhatti, MD, MS, FACS kamibhatti92@gmail.com HMC Medical Corporation, Al Khor, Qatar Assistant Professor of Urology, Qatar University, Qatar Specialist Urology, HMC Medical Corporation, Al Khor, Qatar Mohamed El-Shazly, MD mshazly2001@yahoo.com Assistant Professor of Urology, Menoufia University, Shebin Elkom 32714, Egypt Juan Antonio Galan, MD jagalanllopis@gmail.com Department of Urology, Dr. Balmis General University Hospital, Alicante Institute for Health and Biomedical Research (ISABIAL), Alicante, Spain Ahmed M. Harraz, MD, MS, FRCS, EBU ahmed.harraz@hotmail.com Professor, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt Consultant, Farwaniya Hospital and Sabah Al Ahmad Urology Center, Kuwait City, Kuwait Sarwar Noori Mahmood, MD sarwarchalabi@yahoo.com Department of Surgery, College of Medicine, University of Sulaymaniyah, Sulaymaniyah, Iraq Renato N. Pedro, MD rnpedro@gmail.com Division of Urology, Faculdade de Medicina São Leopoldo Mandic de Campinas, Sao Paulo, Brazil Pablo Vargas, MD pavaran5@gmail.com Marina Baixa Hospital, La Vila Joiosa, Alicante, Spain Athanasios Papatsoris, MD agpapatsoris@yahoo.gr 2nd Department of Urology, School of Medicine, Sismanoglio Hospital, National and Kapodistrian University of Athens, U-merge Scientific Office Alberto Trinchieri, MD alberto.trinchieri@gmail.com Noor Buchholz, MD U-merge, Scientific Office Conflict of interest: The authors declare no potential conflict of interest.