Predictive ability of Guy's stone score in pediatric patients undergoing percutaneous nephrolithotomy

Validation of stone-kidney size score to predict outcome and complications of pediatric percutaneous nephrolithotomy

INTRODUCTION

The prevelance of urinary system stone disease in children is emphasizing the need for minimally invasive treatments to decrease morbidity and recurrence risk. Percutaneous nephrolithotomy (PCNL) has emerged as a preferred approach for pediatric patients with complex stones due to its minimally invasive nature, including miniaturized and vacuum-assisted access sheaths, advanced laser technology and tubeless and outpatient procedures. However, adult scoring systems have proven ineffective in predicting success and complications in pediatric PCNL. This highlights the need for specialized scoring systems, such as the Stone-Kidney Size (SKS) scoring system, tailored to pediatric patients and will be evaluated in our study for its association with the stone-free rate (SFR) and complications.

MATERIALS AND METHODS

The data of 144 patients aged <17 years who had undergone PCNL between January 2008 and December 2019 were evaluated retrospectively. Demographics, stone characteristics, perioperative/postoperative outcomes were recorded for each patient. The SKS scoring system comprises the stone kidney index (SKI) and the number of stones, assigns one or two points based on single or multiple stones and an SKI value of <0.3 or ≥0.3, respectively. The SKI is computed by dividing the stone's longest axis by the kidney's longest axis. Residual stones less than 4 mm on non-contrast computed tomography are considered clinically insignificant residual fragments (CIRFs). Stone-free and CIRF patients were considered successful results. The relationship between the SKS scoring system and SFR, success, and complication rates after surgery was investigated. Statistical analyses were conducted using SPSS 22.0 software.

RESULTS

The SFR was 67.36% and 74.31% when CIRF patients were included, respectively, with a complication rate of 27%. In multivariate analysis, stone treatment history, stone burden, and SKS score were statistically significantly associated with SFR (p < 0.001, p = 0.032, p < 0.001, respectively). Furthermore, the SKS score was the only variable that showed a statistically significant relationship with success. No significant association was found between SKS score and complications (p = 0.342).

DISCUSSION

Our study demonstrates a relationship between the SKS scoring system and SFR in pediatric PCNL patients. However, shortcomings have been observed in its capacity to accurately predict post-PCNL complications. Despite being a retrospective analysis and having a single-center design, our study externally validates the relationship between the SKS scoring system and SFR after pediatric PCNL.

CONCLUSIONS

The SKS scoring system is associated with SFR in pediatric patients undergoing PCNL; however, this relationship has not been established for complications.

Current status of nomograms and scoring systems in paediatric endourology: A systematic review of literature

INTRODUCTION

The incidence of paediatric kidney stone disease is increasing worldwide, with the requirement for endourological interventions mirroring this. Multiple nomograms, grading tools and scoring systems now exist in the adult setting, which aim to enhance the pre-operative planning and decision-making associated with these surgeries. In recent years, there has been increasing interest in nomograms dedicated for use in the paediatric setting. This study provides an up-to-date review and assessment of available paediatric endourology nomograms and scoring systems.

METHODS

A comprehensive search of worldwide literature was conducted according PRISMA methodology. Studies describing paediatric-specific endourology nomograms, scoring systems or grading tools and studies externally validating these tools, or existing adult tools in a paediatric population, were evaluated and included in the narrative data synthesis.

RESULTS

A total of 7 endourology nomograms were identified. 4 were paediatric-specific, 2 for shockwave lithotripsy, 1 for percutaneous nephrolithotomy or ureteroscopy and 1 for percutaneous nephrolithotomy specifically. Only the 2 shockwave lithotripsy nomograms have been externally validated in 4 further studies and showed efficacy in predicting treatment success. 3 adult tools, all specific to PCNL have been investigated and validated in a paediatric setting in 11 studies. In general, they showed efficacy in the prediction of stone free rate but were poor at predicting likelihood of complications.

CONCLUSION

A limited number of paediatric-specific endourology predictive nomograms are available to aid in the management of kidney stone disease, with the strongest evidence supporting those designed for shockwave lithotripsy. Although 3 adult tools have been implemented, there are problems applying these to the paediatric setting and further development of paediatric-specific tools is necessary.

Comparison between prone and supine nephrolithotomy in pediatric population: a double center experience

PURPOSE

Stone disease in the pediatric age is an increasing issue. Percutaneous Nephrolithotomy (PNL) can be used for larger and complex stones. As in adults it can be performed in the supine or prone position.

METHODS

We retrospectively reviewed two centers' experience in prone and supine PNL in children to analyze its results and complications.

RESULTS

33 patients underwent prone and 19 supine procedures. Patients in the prone group were younger than in the supine, while no significant differences were found in stone burden, access size, operative time or complications. Complications were: 8 and 4 Clavien 1 for the prone and supine group, respectively, one case of urosepsis (4b) in the prone and 2 cases of Clavien 3 in the supine group (double J stent placement for renal colic and ureteroscopy for steinstrasse). Tubeless procedures and mean nephrostomy time were in favor of the supine group, whereas fluoroscopy time and ureteral drainage stay were in support of the prone group. Stone free rate was better in the supine group (83.3 vs 66.6%), possibly reflecting the capability to perform a combined approach in 12 patients (allowing to reach all the calyx with simultaneous anterograde and retrograde access) or younger age in the prone group (13 vs 2 patients ≤5 years), with no differences in stone burden.

CONCLUSIONS

Supine approach seems to guarantee higher stone-free rates. Larger series are necessary to determine what the best technique is in terms of X-ray exposure, operative time and complications.

A systematic review of nomograms used in urolithiasis practice to predict clinical outcomes in paediatric patients

INTRODUCTION

Nomograms, used to predict the risk and success of treatment of urinary tract stones, are being used in paediatric clinical practice. However, no studies have determined the best prediction model. This study aimed to identify the most robust nomogram(s) for predicting clinically relevant outcomes in urinary stone disease in paediatric patients.

METHODS

The EMBASE, MEDLINE, Cochrane Systematic Reviews, and Cochrane Central Register of Controlled Trials via Ovid were searched for publications on May 13, 2021. No study design and publication year limitations were applied. The risk of bias in the included studies was determined using PROBAST.

RESULTS

The review included fourteen studies, involving 3888 paediatric patients. We identified seven prognostic stone nomograms (Dogan, Onal, CMUN, SKS, Guy's stone score, S.T.O.N.E and CROES) that were validated for use in paediatric patients. Both Dogan and Onal scores were developed and internally and externally validated in different studies with similar AUC scores between 0.6 and 0.7. For PCNL practice, two nomograms were developed and internally validated (CMUN, SKS) but not externally validated. The Guy's stone score was found to have the lowest overall accuracy in predicting stone-free rates in the externally validated nomograms studies. Nine of the fourteen studies included were judged as having a high risk of bias in their overall judgement.

CONCLUSION

The systematic review findings should be interpreted with caution given the heterogeneity of included studies. There is no difference between the use of the Dogan or Onal score for predicting outcomes associated with ESWL. For predicting outcomes of PCNL, CROES had the greatest supportive evidence, whilst the SKS or CMUN scores lack external validation and require further evaluation to assess their utility in predicting PCNL outcomes.

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.

Critical Application of Adult Nephrolithometric Scoring Systems to Children Undergoing Mini-Percutaneous Nephrolithotomy

Objective: To evaluate and compare the ability of the Guy's stone score (GSS), the S.T.O.N.E. nephrolithometry, and the Clinical Research Office of the Endourology Society (CROES) nomogram to predict the outcome of mini-percutaneous nephrolithotomy (MPNL) in children, and to identify which of the predictors involved in these scoring systems can separately affect this outcome. Patients and Methods: All children younger than 14 years who had MPNL in our center over a period of 3 years were included prospectively. Bivariate analyses were done to evaluate the associations of the three scoring systems and the predictors composing them with single-session stone clearance and complications. Receiver operating characteristic (ROC) curve analyses of the three scoring systems were conducted to evaluate and compare their abilities to predict the outcomes. Decision curve analyses for the three scoring systems were conducted to evaluate the clinical benefit of using each of them to predict stone clearance. Results: We consecutively enrolled 92 renal units in 89 children with a median age of 9.5 years. Single-session stone clearance was achieved in 76 (82.6%) renal units. Complications occurred with 19 (20.7%) procedures. Stone multiplicity (p = 0.043), staghorn stone (p = 0.007), prior stone treatment (p < 0.001), number of calices involved (p = 0.006), stone burden (p = 0.003), GSS (p < 0.001), S.T.O.N.E. nephrolithometry (p = 0.012), and CROES nomogram (p < 0.001) had significant associations with stone clearance. Only stone attenuation was significantly associated with complications (p = 0.031). For prediction of stone clearance, CROES nomogram demonstrated the greatest area under the ROC curve and the greatest net benefit on decision curve analyses. Conclusions: For children undergoing MPNL, CROES nomogram is the best to predict stone clearance. However, none of the studied scoring systems predicted complications efficiently.

Comparison of Guy's Stone Score and clinical research of the endourological society nomogram for predicting surgical outcomes after pediatric percutaneous nephrolithotomy: a single center study

BACKGROUND

The aim of this study was to compare the efficacy of Guy's Stone Score (GSS) and Clinical Research of the Endourological Society (CROES) Nomogram in predicting PCNL outcomes in the pediatric patients with kidney stone.

METHODS

A retrospective review of the clinical data of 120 pediatric patients who underwent PCNL between August 2004 and February 2016 was performed. Patients were grouped according to stone-free (SF) status and complication status. The patients whose history, preoperative physical examination records, biochemical analysis, imaging records were available and who did not neglect the follow-up, were included in the study. The stone size measurement and the scoring system calculation were always performed by the same surgeon. Multivariate logistic regression analysis were performed to identify the factors associated with SF status and complication status.

RESULTS

CROES score was significantly higher in SF patients compared to the patients with residual stones (P=0.009), while stone burden and GSS were significantly lower (P=0.023 and P=0.025). Median hospitalization day of patients with complications was significantly higher compared to the patients without complication (P=0.005). To have stones located in multiple calyces was the only statistically significant condition when two groups were compared (P=0.014). In multivariate analysis, CROES score was the independent factor associated with SF status (OR:0.984 95% CI: 0.959-1.010 P=0.017) and to have stones located in multiple calyces was the independent factor associated with complication status (OR:0.265 95% CI:0.087-0.808 P=0.02).

CONCLUSIONS

CROES nomogram is associated with the SFR while GSS is not. Both scoring systems do not have predictive accuracy on complication status. Further studies are required to make modifications in the scoring systems in the pediatric population.