Nomogram and scoring system for predicting stone-free status after extracorporeal shock wave lithotripsy in children with urolithiasis

Quadruple-D score in the success rate of extracorporeal shock wave lithotripsy of renal stones in pediatric population

OBJECTIVES

Evaluation of the validity of the Quadruple-D score in the prediction of success in pediatric stone disease.

MATERIALS AND METHODS

Of the 292 children treated with SWL between 2007 and 2023, a total of 158 children who had adequate follow-up data and evaluated with non-contrast computed tomography before SWL, were included in the study. Parameters were calculated for each of the stone volume (SV), skin-to-stone distance (SSD), stone density (SD) and stone location (SL) variables. Receiver operator characteristic analysis was used to set cut-off values. Quadruple-D scores were calculated, and success rates were determined for each score. Stone-free status was determined as complete clearance after three months of final SWL.

RESULTS

The median age of the study group was 8 (range 1 to 16). One hundred and one of the 158 (64%) children had stone-free status. Mean SV, SSD and SD values were significantly higher in SWL failed group than stone-free group after detecting cutoff values of 150 mm3, 6.7 cm, and 540 HU, respectively. Stone-free rates were detected as 19.6%, 24.7%, 37.2%, 76.2%, and 90.2% with the Quadruple-D scores of 0, 1, 2, 3 and 4 points.

CONCLUSIONS

Quadruple-D scoring system can further improve Triple-D scoring system by adding stone position parameter to clarify SFR with a simple and easy calculation. We believe that the Quadruple-D score will have better clinical significance than the Triple-D scoring system in predicting the success of SWL in children.

Using ensemble learning and hierarchical strategy to predict the outcomes of ESWL for upper ureteral stone treatment

Urinary tract stones are a common and frequently recurring medical issue. Accurately predicting the success rate after surgery can help avoid ineffective medical procedures and reduce unnecessary healthcare costs. This study collected data from patients with upper ureter stones who underwent extracorporeal shock wave lithotripsy, including cases of successful as well as unsuccessful stone removal after the first and second lithotripsy procedures, and constructed prediction systems for the outcomes of the first and second lithotripsy procedures. Features were extracted from three categories of information: patient characteristics, stone characteristics, and extracorporeal shock wave lithotripsy machine data, and additional features were created using Feature Creation. Finally, the impact of features on the models was analyzed using six methods to calculate feature importance. Our prediction model for the first lithotripsy, selected from among 43 methods and seven ensemble learning techniques, achieves an AUC of 0.91. For the second lithotripsy, the AUC reaches 0.76. The results indicate that the detailed and binary information provided by patients regarding their history of stone experiences contributes differently to the predictive accuracy of the first and second lithotripsy procedures. The prediction tool is available at https://predictor.isu.edu.tw/ks.

Stone decision engine accurately predicts stone removal and treatment complications for shock wave lithotripsy and laser ureterorenoscopy patients

Kidney stones form when mineral salts crystallize in the urinary tract. While most stones exit the body in the urine stream, some can block the ureteropelvic junction or ureters, leading to severe lower back pain, blood in the urine, vomiting, and painful urination. Imaging technologies, such as X-rays or ureterorenoscopy (URS), are typically used to detect kidney stones. Subsequently, these stones are fragmented into smaller pieces using shock wave lithotripsy (SWL) or laser URS. Both treatments yield subtly different patient outcomes. To predict successful stone removal and complication outcomes, Artificial Neural Network models were trained on 15,126 SWL and 2,116 URS patient records. These records include patient metrics like Body Mass Index and age, as well as treatment outcomes obtained using various medical instruments and healthcare professionals. Due to the low number of outcome failures in the data (e.g., treatment complications), Nearest Neighbor and Synthetic Minority Oversampling Technique (SMOTE) models were implemented to improve prediction accuracies. To reduce noise in the predictions, ensemble modeling was employed. The average prediction accuracies based on Confusion Matrices for SWL stone removal and treatment complications were 84.8% and 95.0%, respectively, while those for URS were 89.0% and 92.2%, respectively. The average prediction accuracies for SWL based on Area-Under-the-Curve were 74.7% and 62.9%, respectively, while those for URS were 77.2% and 78.9%, respectively. Taken together, the approach yielded moderate to high accurate predictions, regardless of treatment or outcome. These models were incorporated into a Stone Decision Engine web application (http://peteranoble.com/webapps.html) that suggests the best interventions to healthcare providers based on individual patient metrics.

Pediatric Stone Disease: Current Trends and Future Directions

Pediatric nephrolithiasis is less common in children than in adults but the incidence has been rising rapidly, and it is now a public health and economic burden in the United States. There are challenges unique to children that should be taken into consideration when evaluating and managing pediatric stone disease. In this review, we present the current research on risk factors, emerging new technologies for treatment of stones and recent investigations on prevention of stones in this population.

Which frequency is better for pediatric shock wave lithotripsy? Low intermediate or high: A systematic review and meta-analysis

Background

To explore the optimal frequency for pediatric extracorporeal shock wave lithotripsy (ESWL) in the treatment of upper urinary stones.

Methods

A systematic literature search was undertaken using PubMed, Embase, Web of Science and Cochrane Central Register of Controlled Trials databases to identify eligible studies published before January 2023. Primary outcomes were perioperative efficacy parameters, including ESWL time, anesthesia time for ESWL sessions, success rates after each session, additional interventions needed, and treatment sessions per patient. Secondary outcomes were postoperative complications and efficiency quotient.

Results

Four controlled studies involving 263 pediatric patients were enrolled in our meta-analysis. In the comparison between the low-frequency and intermediate-frequency groups, we observed no significant difference as regards anesthesia time for ESWL session (WMD = −4.98, 95% CI −21.55∼11.58, p = 0.56), success rates after ESWL sessions (first session: OR = 0.02 95%CI −0.12∼0.17, p = 0.74; second session: OR = 1.04 95%CI 0.56∼1.90, p = 0.91; third session: OR = 1.62 95%CI 0.73∼3.60, p = 0.24), treatment sessions needed (WMD = 0.08 95%CI −0.21∼0.36, p = 0.60), additional interventions after ESWL (OR=0.99 95%CI 0.40∼2.47, p = 0.99) and rates of Clavien grade 2 complications (OR = 0.92 95%CI 0.18∼4.69, p = 0.92). However, the intermediate-frequency group may exhibit potential benefits in Clavien grade 1 complications. In the comparison between intermediate-frequency and high-frequency, the eligible studies exhibited higher success rates in the intermediate-frequency group after the first session, the second session and the third session. More sessions may be required in the high-frequency group. With respect to other perioperative, postoperative parameters and major complications, the results were similar.

Conclusions

Intermediate-frequency and low-frequency had similar success rates and seemed to be the optimal frequency for pediatric ESWL. Nevertheless, future large-volume, well-designed RCTs are awaited to confirm and update the findings of this analysis.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022333646.

Is Triple D Score Effective to Predict the Stone-Free Rate After Shockwave Lithotripsy in Pediatric Population?

Introduction: Triple D score was developed using skin-to-stone distance (SSD), stone density (SD), and stone volume (SV) for prediction of extracorporeal shockwave lithotripsy (SWL) outcomes in adults. SWL is the first-line treatment method for kidney stones <2 cm in children, however, it was not validated in the pediatric population. This article aims to validate Triple D score in pediatric patients. Materials and Methods: Of the 269 children treated with SWL between 2007 and 2021, a total of 147 children who had adequate follow-up data and evaluated with noncontrast CT before SWL were included in the study. Parameters were calculated for each of the SV, SSD, and SD variables. Receiver operator characteristic analysis was used to set cutoff values. Triple D scores were calculated, and success rates were determined for each score. Stone-free status was determined as complete clearance after 3 months of final SWL. Results: The median age of the study group was 7 years (range 1-16). Ninety-three of the 147 (63%) children had stone-free status. Mean SV, SSD, and SD values were significantly higher in the SWL-failed group than in the stone-free group after detecting cutoff values of 155 mm³, 6.5 cm, and 550 HU, respectively. Stone-free rates were detected as 23.8%, 35.1%, 74.0%, and 92.0% with the Triple D scores of 0, 1, 2, and 3 points. Conclusions: Our study confirms that Triple D scores support the SWL outcomes in the pediatric population. We believe that our research on Triple D score validation in children is of great clinical importance although various factors may affect to predict the success of SWL. IRB Approval: 2021/514/194/14.

Complication rate after pediatric shock wave lithotripsy according to Clavien-Dindo grading system: results from a systematic review and meta-analysis of the existing literature

PURPOSE

Shockwave lithotripsy (SWL) is a minimally invasive technique utilized for renal and ureteric stones in children. Despite being considered safe, certain complications have been recorded. We performed this systematic review and meta-analysis to provide a pooled analysis of Clavien-Dindo graded complications after SWL in children.

METHODS

MEDLINE/PubMed, Scopus and Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews, were screened from inception to 12/02/2022 by two authors independently. Only randomized controlled trials providing Clavien-Dindo classification or relevant clinical information were considered eligible. Overall complications were calculated using the aggregate number of each complication divided by the total number of patients in studies with data.

RESULTS

Pooled analysis revealed that from children treated with SWL, 27.7% [95% CI 13.1-49.4] suffered Clavien I complications, 4.9% [95% CI 3.1-7.6] Clavien II complications, 2.7% [95% CI 1.6-4.7] Clavien III complications, 2.3% [95% CI 1.3-4] Clavien IV complications, while no Clavien V complications were recorded. In total, 28.1% [95% CI 15.6-45.3] of children suffered minor complications (Clavien-Dindo I-II), while 3% [95% CI 1.8-5] major complications (Clavien-Dindo III-V). Pooled analysis revealed that 10.7% [95% CI 3.2-30.1] of patients suffered macroscopic hematuria, 7.3% [95% CI 2.1-22.7] pain, 5.5% [95% CI 3.3-9] steinstrasse, 5.3% [95% CI 3-9.3] fever, 2.2% [95% CI 0.8-5.6] sepsis, 1.1% [95% CI 0.3-3.7] urinoma, 1% [95% CI 0.4-2.7] symptomatic hematoma and 1% [95% CI 0.3-2.7] asymptomatic hematoma. Need for re-treatment was 42.6% [95% CI 31.4-54.7] and need for auxiliary procedures was 11.8% [95% CI 8.5-16.1].

CONCLUSION

SWL is an irreplaceable tool for treating urolithiasis in children. Although a minimally invasive technique, parents and children should be adequately informed about the risk of minor/major complications.

Complication rate after pediatric shock wave lithotripsy according to Clavien-Dindo grading system: results from a systematic review and meta-analysis of the existing literature

PURPOSE

Shockwave lithotripsy (SWL) is a minimally invasive technique utilized for renal and ureteric stones in children. Despite being considered safe, certain complications have been recorded. We performed this systematic review and meta-analysis to provide a pooled analysis of Clavien-Dindo graded complications after SWL in children.

METHODS

MEDLINE/PubMed, Scopus and Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews, were screened from inception to 12/02/2022 by two authors independently. Only randomized controlled trials providing Clavien-Dindo classification or relevant clinical information were considered eligible. Overall complications were calculated using the aggregate number of each complication divided by the total number of patients in studies with data.

RESULTS

Pooled analysis revealed that from children treated with SWL, 27.7% [95% CI 13.1-49.4] suffered Clavien I complications, 4.9% [95% CI 3.1-7.6] Clavien II complications, 2.7% [95% CI 1.6-4.7] Clavien III complications, 2.3% [95% CI 1.3-4] Clavien IV complications, while no Clavien V complications were recorded. In total, 28.1% [95% CI 15.6-45.3] of children suffered minor complications (Clavien-Dindo I-II), while 3% [95% CI 1.8-5] major complications (Clavien-Dindo III-V). Pooled analysis revealed that 10.7% [95% CI 3.2-30.1] of patients suffered macroscopic hematuria, 7.3% [95% CI 2.1-22.7] pain, 5.5% [95% CI 3.3-9] steinstrasse, 5.3% [95% CI 3-9.3] fever, 2.2% [95% CI 0.8-5.6] sepsis, 1.1% [95% CI 0.3-3.7] urinoma, 1% [95% CI 0.4-2.7] symptomatic hematoma and 1% [95% CI 0.3-2.7] asymptomatic hematoma. Need for re-treatment was 42.6% [95% CI 31.4-54.7] and need for auxiliary procedures was 11.8% [95% CI 8.5-16.1].

CONCLUSION

SWL is an irreplaceable tool for treating urolithiasis in children. Although a minimally invasive technique, parents and children should be adequately informed about the risk of minor/major complications.

Diagnosis and Management of Nephrolithiasis in Children

The incidence of kidney stones in children is increasing. Approximately two-thirds of pediatric cases have a predisposing cause. Children with recurrent kidney stones have an increased higher risk of developing chronic kidney. A complete metabolic workup should be performed. Ultrasound examination is the initial imaging modality recommended for all children with suspected nephrolithiasis. A general dietary recommendation includes high fluid consumption, dietary salt restriction, and increased intake of vegetables and fruits. Depending on size and location of the stone, surgical intervention may be necessary. Multidisciplinary management is key to successful treatment and prevention.

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.

How well do ESWL nomograms predict treatment success in pediatric patients?

Objective:

To study was to identify the variables that influence the outcomes of pediatric SWL patients in our clinic and to compare our findings to previously published nomograms.

Methods:

All children who underwent SWL at a single center between 2005 and 2020 were included in this retrospective study. Depending upon the age and mental state of the children, SWL procedures were performed with or without anesthesia. Data from the hospital information system were obtained on patient characteristics, metabolic evaluation, imaging, SWL details, and post-procedure results, and their correlation with the Onal and Dogan nomograms was evaluated.

Results:

The present study included 112 pediatric patients in total. The average age was 8.22 ± 4.9 (83.3 ± 58.1 months, 4 months–16 years), and the median stone size was 9.5 ± 3.2 mm (4–20 mm). Even though there was quite a significant positive correlation between age and the number of shots and the intensity of shots (intensity and number of shots increased with increasing age), there was no statistical difference in the number of sessions and stone-free rates. The number of shots and sessions was significantly lower in patients with hydronephrosis ( N = 70) than in those without ( N = 42) ( p < 0.001). When the stone-free rates of patients without and with hydronephrosis were compared, it was discovered that they were 69.05% and 92.86%, respectively, which was statistically significant ( p < 0.01).

Conclusions:

It is believed that the nomograms developed for SWL in pediatric patients should be reviewed, and larger, prospective studies should be conducted.

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.

Predicting ESWL success by determination of Hounsfield unit on non-contrast CT is clinically irrelevant in children

The necessity of determining stone density by non-contrast computerized tomography (NCCT) before extracorporeal shock wave lithotripsy (ESWL) is a controversial topic due to the radiation exposure. We aimed to investigate whether stone density is helpful in predicting the success of ESWL in pediatric patients or not. In this retrospective study, database of a single center was used to identify 232 children aged between 2 and 16 years. Patients with abnormal renal anatomy, distal obstruction, a known cystine stone disease, a previous history of an intervention regarding stone, and an insufficient follow-up period (< 3 months) were excluded from the study. A total of 209 patients were included in the study (94 with NCCT, 115 without NCCT). Groups were compared in terms of stone size, stone location, and stone-free rate at 3 months after a single ESWL session. The mean age was 6.17 ± 3.27 years and 120 (57.4%) of the patients were male and 89 (42.6%) were female. Mean stone size was 11.7 mm in NCCT group and 12.3 mm in non-NCCT group (p 0.128). The complete stone clearance rate in NCCT and non-NCCT group at 3 months after ESWL was 57.4% (54/94) and 54.7% (63/115), respectively, and there was no statistically significant difference (p 0.316). In conclusion, unnecessary NCCT use should be avoided before ESWL considering the similar success rates after ESWL and the risk of exposure to radiation.

Ability of ESWL nomograms to predict stone-free rate in children

INTRODUCTION

We aimed to evaluate whether the pediatric extracorporeal shock wave lithotripsy (ESWL) nomograms can predict stone-free status in children effectively and whether they are applicable to our series. We hypothesize that two current nomograms predicting successful treatment with ESWL in pediatric patients are valid.

STUDY DESIGN

We evaluated 415 renal units (children <18 years) with eligible data who received ESWL treatment for upper urinary tract stones. Children's age, gender, stone size, stone surface area, stone location and history of previous intervention were recorded. Children with no residual fragments after ESWL treatment were designated as stone-free. The nomograms described by Dogan and Onal were implemented to our series for the prediction of stone-free status.

RESULTS

Mean age of children was 64.7 ± 57.2 months. Male to female ratio was 219:196.78.8% (327) of children had single stone. Mean stone size was 10.0 ± 3.7 mm and mean stone surface area was 380.0 ± 72.2 mm². Our stone-free rate after single ESWL session was 52.5% (218/415). Mean residual stone size and stone surface area after single session was 6.4 ± 3.3 mm and 36.0 ± 44.2 mm² respectively. There were no significant difference between stone-free children and children with residual fragments regarding gender, age and history of previous intervention. Mean stone size and stone surface area in stone-free children were lower and lower pole stones had the lowest stone-free rate (p < 0.05). Area under curve for Dogan and Onal nomogram were 0.628 and 0.580 respectively in ROC analysis (0.05). The agreement between Dogan and Onal score was moderate in our series. In multivariate analysis only stone surface area and Dogan score found to be independent predictors of stone-free status (p < 0.05).

DISCUSSION

Only one study has assessed both nomograms in the literature. Both nomograms are reported to be independent predictors of stone free status. ROC analysis in our study revealed fair accuracy for both nomograms with higher area under curve for Dogan nomogram. Higher accuracy for both nomograms were reported by other authors. These nomograms offer practical data but more effective tools are needed to be developed for the prediction of stone-free status in pediatric ESWL.

CONCLUSIONS

Stone size and stone surface area are associated with stone clearance. Dogan and Onal nomograms can be useful in prediction of stone-free status in children. Dogan nomogram is superior to Onal nomogram.

Ureteral wall thickness is an independent parameter affecting the success of extracorporeal shock wave lithotripsy treatment in ureteral stones above the iliac crest

BACKGROUND

To investigate the relationship between ureteral wall thickness (UWT) and other variables of patients who underwent extracorporeal shock wave lithotripsy (SWL) in the primary treatment of the ureteral stone above the iliac crest level.

MATERIAL AND METHODS

A total of 147 patients aged 18 years and older, who underwent SWL in our clinic between December 2016 and December 2019 for the treatment of ureteral stones above the iliac crest level and had non-contrast enhanced abdominal computed tomography scans before the procedure were included in the clinical study. The results were evaluated at 3 months after SWL. The absence of residual fragments was considered as stone-free status, and the existence of any size residual fragment was considered as treatment failure.

RESULTS

In our study, the mean age of the patients was 42.4 ± 12.8 years, and the stone-free rate was 92.5%. The median transverse stone size was 7.5 mm (min 2.8-max 15), and the median UWT was 4.2 mm (1-8.7). In the multivariate analysis, UWT (P = .002) and multiple stone presence (P = .027) were found to be independent factors affecting stone-free status. In the receiver operating characteristic curve analysis, the optimal threshold value for UWT was determined as 5.25 mm.

CONCLUSIONS

We found that UWT was the most important independent variable associated with increased failure in SWL treatment. The presence of multiple stones was another independent factor that increased the failure rates. Using SWL technology through experience accumulated with the mechanical hardware of the machine, we can select patients who are more suitable for this treatment and improve treatment outcomes.

European Association of Urology and European Society for Paediatric Urology Guidelines on Paediatric Urinary Stone Disease

CONTEXT

Paediatric stone disease is an important clinically entity and management is often challenging. Although it is known that the condition is endemic in some geographic regions of the world, the global incidence is also increasing. Patient age and sex; the number, size, location, and composition of the stone; and the anatomy of the urinary tract are factors that need to be taken into consideration when choosing a treatment modality.

OBJECTIVE

To provide a general insight into the evaluation and management of urolithiasis in the paediatric population in the era of minimally invasive surgery.

EVIDENCE ACQUISITION

A nonsystematic review of the literature on management of paediatric urolithiasis was conducted with the aim of presenting the most suitable treatment modality for different scenarios.

EVIDENCE SYNTHESIS

Because of high recurrence rates, open surgical intervention is not the first option for paediatric stone disease, except for very young patients with very large stones in association with congenital abnormalities. Minimally invasive surgeries have become the first option with the availability of appropriately sized instruments and accumulating experience. Extracorporeal shockwave lithotripsy (SWL) is noninvasive and can be carried out as an outpatient procedure under sedation, and is the initial choice for management of smaller stones. However, for larger stones, SWL has lower stone-free rates and higher retreatment rates, so minimally invasive endourology procedures such as percutaneous nephrolithotomy and retrograde intrarenal surgery are preferred treatment options.

CONCLUSIONS

Contemporary surgical treatment for paediatric urolithiasis typically uses minimally invasive modalities. Open surgery is very rarely indicated.

PATIENT SUMMARY

Cases of urinary stones in children are increasing. Minimally invasive surgery can achieve high stone-free rates with low complication rates. After stone removal, metabolic evaluation is strongly recommended so that medical treatment for any underlying metabolic abnormality can be given. Regular follow-up with imaging such as ultrasound is required because of the high recurrence rates.

What is the optimal frequency in shock wave lithotripsy for pediatric renal stones? A prospective randomized study

The aim of the study is to compare the effects of varying frequency rates (60, 90, and 120 SWs/min) on the stone free rate and complication rates of pediatric SWL. 75 children with renal stones were divided into 3 groups depending on the SW frequency applied. Group 1. low (60 SWs/min), Group 2. intermediate (90 SWs/min) and Group 3. high (120 SWs/min) frequency. Patient demographics (age, gender, BMI), stone (location, size, laterality), and SWL (total number of sessions, shock waves, anesthesia time) related parameters were documented. Postoperative success, complication rates, and the need for additional interventions were comparatively evaluated. There was no significant difference regarding the patient demographics, stone characteristics, SWL parameters, postoperative complication rates, need for additional interventions as well as efficacy quotient between all (p > 0.05). The stone free rates were significantly lower in cases with high frequency, whereas there was no statistically significant difference between the intermediate and low frequency groups (p > 0.05). Although not statistically significant; low frequency application may be more advantageous than intermediate as lower number of high energy shock waves required which may cause less tissue damage. On the other hand, despite lack of a statistically significant difference, relatively longer anesthesia time may constitute a disadvantage for lower frequency. We believe that considering the growing nature of the child kidney application of low frequency (60 SWs/min) will be advantageous. However, we believe that further studies with larger series of cases are needed to make a clear-cut differentiation between low and intermediate SW applications.

Factors to predict shock-wave lithotripsy results in pediatric patients and external validation of a nomogram

OBJECTIVE

To evaluate the accuracy of the Dogan nomogram in predicting stone-free (SF) rate after a single shock wave lithotripsy (SWL) session and evaluate factors that predict SWL results in children.

PATIENTS AND METHODS

The study included 68 patients under 18 years of age who had been treated with SWL for radiopaque upper urinary tract stones in our tertiary centre from January 2010 to December 2016. The median age is 50 (6-207) months and median follow-up period is 9 (4-50) months. Patients with known cystine stone disease, abnormal renal anatomy, urinary diversion and multiple stones located in different calyces were excluded like in the original nomogram study. SF status was evaluated by performing plain abdominal radiography and urinary ultrasonography 2 weeks after each SWL session. Patients who were completely free of stones were considered to be SF. Multiple logistic regression analyses were performed to determine the variables affecting SF status. The bootstrap method with 1,000 replicates was used for the external validity of a nomogram developed by Dogan.

RESULTS

SF rates for each SWL session were determined as 54.4% (37/68) for the first session, 33.3% (7/21) for the second session and 55.6% (5/9) for the third session. Overall, the SF rate was 72.1% (49/68). Multiple logistic regression analysis showed positive and significant correlations of age and stone size with risk of SWL failure. The external calibration plot showed a nearly good validation with Dogan nomogram to predict SWL failure in first session.

CONCLUSION

Our study demonstrates that the Dogan nomogram can be used to predict the SF status after one session of SWL in pediatric patients.

Pediatric stone disease: Current management and future concepts

Treatment of pediatric urolithiasis consists of medical and surgical approaches. The main goal of the treatment is to prevent stone recurrence by avoiding multiple surgical interventions. In recent years, many innovations have been reported in the medical diagnostic evaluation protocol and in surgical treatment. According to recent reports, single mutations could be responsible for a larger proportion of renal stones. This etiologic feature holds the potential to change the management in stone prevention from metabolically directed therapy to more specific approaches. In addition, miniaturized instruments have been adopted in clinical practice. In recent years, minimally invasive endoscopic surgery is the treatment of choice in pediatric urolithiasis. This review aims to assess the current literature on medical and surgical treatment options for pediatric urolithiasis. We also aim to provide an overview of potential future advances.

Extracorporeal shock wave lithotripsy in Indian children: Predictors of outcome and validation of pre-treatment nomograms

BACKGROUND

Although multiple variables have been shown to affect outcomes in pediatric lithotripsy (ESWL), there is no consensus on the same. Nomograms combine multiple variables and provide an objective prediction of outcomes. Two nomograms have been previously described and validated in two studies from the same geographical area. External validation in multiple settings is needed, as a nomogram's performance may vary with time, geographical area and clinical scenario.

OBJECTIVES

This study aimed to identify variables influencing pediatric ESWL outcomes, validate published nomograms and describe the clinical and metabolic profile of Indian children treated with ESWL.

DESIGN

This retrospective cohort study included all children who underwent ESWL from 2002 to 2019 at a single centre. ESWL was performed under general anaesthesia. Mid and lower ureteric calculi were treated in prone and the rest in supine position. 1500-2000 shocks were delivered at a voltage of 12-16 kV. Data pertaining to patient characteristics, metabolic evaluation, imaging, ESWL details and post-procedure outcomes were obtained from the hospital information system and these variables, along with Onal and Doğan scores, were correlated with stone clearance. Cut-offs for Onal and Doğan scores were determined using receiver operator characteristic (ROC) curve analysis and compared with area under the curve (AUC). Complications, ancillary procedures and metabolic abnormalities were recorded.

RESULTS

A total of 66 children (76 renal units) were included. Mean age was 5.5 years (Range 6 months-14 years) and median stone size, 12 mm (IQR 9, 15.25). Average treatment sessions were 1.8 ± 0.99. Median shocks in the stone-free group and those who failed treatment were 1750 (IQR 1500, 3000) and 3250 (IQR 1750, 4750) respectively. The remaining variables are depicted in Table 1. The stone free rate was 63.2%. Fragments <4 mm were seen in 19 (25%). Efficacy Quotient was 40. The AUC for Doğan nomogram (cut-off <199.5) was 0.761 while that for Onal nomogram (cut-off <2.5) was 0.762 and 0.771 after one and three shocks respectively. On multivariate analysis, age, multiple calculi, Onal and Doğan scores were predictive of clearance. Doğan score had higher specificity. Complications were seen in 16 (21%) and ancillary procedures needed in 7 (9.2%). Metabolic abnormalities were seen in 84.8%, the commonest being hyperoxaluria. Mixed stones were most frequent.

CONCLUSIONS

Lithotripsy in children is safe and effective. Older age, presence of multiple calculi, higher Onal and Doğan scores are predictive of treatment failure.

Effectiveness of ultrasound-guided shockwave lithotripsy and predictors of its success rate in pediatric population: A report from a national reference center

OBJECTIVE

Shockwave lithotripsy (SWL) remains a well-established treatment modality for many of the pediatric renal and ureteral stones. Repeated SWL sessions carry limitations due to the use of general anesthesia and X-ray radiation. The objective of our study was to evaluate stone-free rate (SFR) of 1-session of SWL for the management of pediatric renal and ureteral stones less than 2 cm performed exclusively under ultrasound guidance and identify factors influencing its success.

METHODS

The study utilized a retrospective cohort design including 124 consecutive pediatric patients with 133 renal and ureteral stones less than 2 cm whom SWL was performed in the period of January 2008 to December 2019. SWL procedures were performed by one expert surgeon in a single, national reference center, exclusively under ultrasound guidance using Modulith® SLK lithotripter. Follow-up was performed in post-SWL 2nd, 4th, 12th weeks and 6 months.

RESULTS

The mean age of the children was 10 years (SD = 6.0) and the mean stone size was 10.4 mm (SD = 3.6 mm). Sedation type of anesthesia was used in 80 patients (64.5%). No major complication was developed, and no ureteral stenting was required in any of the patient following SWL. The SFR following 1-session of SWL was 88.0% at 12-week. Younger age (P = 0.002), sedation type of anesthesia (P = 0.001) and presence of radiolucent stones (P = 0.033) significantly improved post-SWL early stone clearance on univariate analysis, the latter being the only significant factor according to final model (P = 0.031).

CONCLUSIONS

Ultrasound-guided SWL represents a safe and effective method for the management of both renal and ureteral stones in children. The SFR following 1-session of SWL at 12-weeks was achieved in 88.0%, the overall success rate after all SWL sessions reaching 91.7%. A higher success rate was observed in children harboring radiolucent stones.

Does Previous Open Stone Surgery Affect the Outcome of Shock Wave Lithotripsy Treatment in Children?

INTRODUCTION

The aim of the study was to evaluate the efficiency of shock wave lithotripsy (SWL) in children who previously underwent ipsilateral open renal stone surgery (ORSS).

METHODS

A total of 315 renal units (RUs) with renal stones underwent SWL treatment in our department over a period of 18 years. A total of 274 RUs (87%) with no history of ORSS were categorized as group 1 and 41 RUs (13%) with a history of ORSS were categorized as group 2. The characteristics of the patients and renal stones, as well as the treatment modalities, were reviewed retrospectively, and the results were compared in terms of the rates of stone-free patients and complications.

RESULTS

The stone-free rates were statistically lower in patients with an existing history of ORSS (p = 0.002), especially for stones located at the lower calyx (p = 0.006). However, there were no differences between groups in the rate of complications (p = 0.75). History of ipsilateral ORSS, age, and stone burden were independent risk factors that predicted a stone-free status in the regression analysis (p = 0.016, p = 0.045, and p = 0.001, respectively).

CONCLUSION

The overall stone-free rate after SWL was found to be significantly lower in children with a history of ORSS than in those without, and this finding was significantly prominent for lower calyx stones. In spite of the possible difficulties in achieving surgical access due to anatomical changes in retrograde intrarenal surgery or mini-/micro-percutaneous nephrolithotomy, we believe that these techniques might be good alternatives for SWL in future cases.

Hounsfield units-a significant predictor of lasering time and energy in the management of upper urinary tract stones using Holmium: Yttrium-Aluminum Garnet lasers

PURPOSE

To study the impact of stone density as assessed by Hounsfield units (HU) on total laser energy (TLE) used and total laser time (TLT) spent in complete fragmentation of upper urinary tract stones. In addition, we also studied the impact of stone composition on the laser energy and time required for fragmentation.

METHODS

Thirty consecutive patients fulfilling inclusion and exclusion criteria were included in the study. Patients with renal or proximal ureteral stones with a size of 5-20 mm were included. Stone fragmentation was performed using Ho:YAG 100 W laser and TLT and TLE were correlated with the HU and stone composition.

RESULTS

The mean stone diameter was 10.83 ± 3.5 mm and the mean HU was 893 ± 315. The mean TLE and TLT were 8.86 ± 3.12 kJ and 18.46 ± 6.9 min, respectively. We observed a strong positive correlation between HU and TLE (r = 0.84, p value < 0.001) and between HU and TLT (r = 0.58, p value = 0.001). However, the stone composition did not influence the lasering energy (p value = 0.36) and lasering time (p value = 0.30). Stone diameter also had significant positive correlation with TLE (r = 0.41; p = 0.02) and TLT (r = 0.54; p- 0.002). When controlling for stone size the correlation of HU with TLE (r = 0.83; p < 0.001) and TLT (r = 0.52; p = 0.004) remained significant.

CONCLUSIONS

HU and stone diameter are significant predictors of TLE and TLT when using Ho:YAG laser for stone fragmentation. However, stone composition and stone location failed to show any significant effect on either of these parameters.

Shockwave lithotripsy for kidney stones as a first-line therapy in children younger than 2 years

BACKGROUND

The incidence of urolithiasis in children has risen worldwide over the last decades with geographical varieties. As pediatric patients begin forming stones earlier in life, they have high risk of recurrence. Extracorporeal shockwave lithotripsy (SWL) is a non-invasive treatment modality that is preferred in the management of pediatric stones. Reports about the safety and efficacy of SWL in patients younger than 24 months are scarce in the literature.

OBJECTIVE

The aim of the study was to evaluate the effectiveness and safety of SWL in patients younger than 24 months. The authors also aimed to assess the validity of the Dogan nomogram in predicting stone-free rates.

STUDY DESIGN

Between January 2009 and March 2019, data of 247 patients younger than 24 months at the time of SWL were retrospectively collected. Analysis was performed on 260 renal units. Success was considered in patients who were completely free of stones after the first session.

RESULTS AND DISCUSSION

The female/male ratio was 103/157, with a median age of 15 (5-24) months, a median stone size of 8 (3-30) mm and a median follow-up period of 7 (3-20) months. Multiple stones and lower calyx stones were observed in 19.6% (51/260) and 23.4% (61/260) of patients, respectively. Complications were detected in 5.8% (15/260) of patients (9 with steinstrasse, 3 with UTI, 2 with vomiting, 1 with hematuria). After the first session, 56.9% (148/260) of patients were stone-free. Forty-six of the failed 112 first sessions underwent second session. A total of 5 patients had a third session. The efficacy quotient was 57%. On univariate analysis, younger age (≤16 months), single stone, small stone size (<10 mm), and non-lower pole location were significant predictors of stone clearance. On multivariate analysis, younger age (=<16 months) and single stone remained significant. The Dogan nomogram score lower than 150 was found to be a good cutoff point to predict better stone clearance (Table).

CONCLUSION

Shockwave lithotripsy is a safe and effective treatment modality in patients younger than 24 months and could be the first option in this particular age-group in whom the other endourological modalities are not always applicable. The Dogan nomogram is reliable in predicting the stone-free rate in this age-group.

Update on Surgical Management of Pediatric Urolithiasis

Urolithiasis has always been a fascinating disease, even more so in children. There are many intriguing facets to this pathology. This article is a nonsystematic review to provide an update on the surgical management of pediatric urolithiasis. It highlights the pros and cons of various minimally invasive surgical options such as extracorporeal shockwave lithotripsy (ESWL), retrograde intrarenal surgery (RIRS), percutaneous nephrolithotomy (PCNL), laparoscopy, and robotics. This article also describes the various intracorporeal disintegration technologies available to fragment the stone, including the newer advancements in laser technology. It also emphasizes the cost considerations especially with reference to the emerging economies. Thus, this manuscript guides how to select the least-invasive option for an individual patient, considering age and gender; stone size, location, and composition; and facilities and expertise available.

Factors that affect outcome of pediatric shock waves lithotripsy with sedoanalgesia

INTRODUCTION

Performing shock wave lithotripsy (SWL) under intravenous sedoanalgesia and the ability to predict the effectiveness of SWL is essential in determining the most appropriate treatment for patients.

PATIENTS AND METHODS

This study consisted of 56 children aged between 1 and 16 years mean age 6.7 ± 4.3 years with renal and ureteric stones who underwent SWL. Incomplete child data were excluded from the study, leaving 47 patients. The procedure was performed under sedoanalgesia with diazepam and ketamine was given intravenously during SWL session. We study the effect of the following factors (age, site, size, opacity of stone, degree of pelvicalyceal dilation, previous urological surgery, number of shock waves, and number of sessions) on stone clearance after SWL.

RESULTS

Forty-seven children range from 1 to 16 years, mean age 6.7 ± 4.3 years. There were 39 (83%) with renal stone and 8 (17%) with ureteric stone. The mean size of stone was 12.2 ± 4.4 mm ranging 6-25 mm. Of 47 children, 36 (76.6%) were stone-free. Age below 6 years, pelvic stones, children without surgery, number of shock waves, and number of sessions were significant factors that affect the stone-free rate after SWL, while the stone size, opacity, and calyceal system dilatation were not statistically significant factors.

CONCLUSIONS

The present analysis shows that stone-free status for children with urolithiasis depends on the age of presentation, previous history of ipsilateral stone treatment, stone location, and number of sessions. Pediatric lithotripsy under intravenous sedoanalgesia is feasible, general anesthesia is not mandatory, and any anesthetic complications were not encountered.

Stones in pregnancy and pediatrics

Urinary stone disease is a highly prevalent condition affecting approximately 10% of the population, and has increased in incidence significantly over the past 20 years. Along with this, the rate of stone disease among women and children is also on the rise. The management of stone disease in specific populations, such as in children and during pregnancy can present unique challenges to the urologist. In both populations, a multi-disciplinary approach is strongly recommended given the complexities of the patients. Prompt and accurate diagnosis requires a high degree of suspicion and judicious use of diagnostic imaging given the higher risks of radiation exposure. In general, management proceeds from conservative to more invasive approaches and must be individualized to the patient with careful consideration of the potential adverse effects. However, innovations in endourologic equipment and techniques have allowed for the wider application of surgical stone treatment in these patients, and significant advancement in the field. This review covers the history and current advances in the diagnosis and management of stone disease in pregnant and pediatric populations. It is paramount for the urologist to understand the complexities of properly managing stones in these patients in order to maximize treatment efficacy, while minimizing complications and morbidity.

Extracorporeal shock wave lithotripsy (ESWL) monotherapy in children: Predictors of successful outcome

INTRODUCTION AND OBJECTIVES

Although extracorporeal shock wave lithotripsy (ESWL) is the first choice for pediatric renal calculi <2 cm, the success rate after the first session is low. This is in contrast to other minimally invasive procedures like percutanous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS), which have higher rates of success. Therefore, the present study sought to identify predictors of success after one session of ESWL.

PATIENTS AND METHODS

A prospective study including 100 children with renal stone burden <2 cm who underwent ESWL at the present institution. The success rate after the first session was analyzed, and the predictors of success were investigated. The success of ESWL monotherapy was defined by absence of any residual fragments after 3 months, on non-contrast spiral computerized tomography (NCCT) scan, without need of any additional intervention.

RESULTS

Between January 2013 and October 2015, 100 children were treated with a Dornier Gemini lithotripter at the present institution. The mean patients age and stone size were 6 years (range: 1.8-14) and 13.1 mm (range: 6-20), respectively. After one session, 47% of patients showed complete clearance 3 months postoperative, those patients versus those who required an additional session or auxiliary procedures were younger in age, with smaller stone size and lower density. On multivariate analysis, only patient age was an independent predictor of success (odds ratio (OR) 0.9; P < 0.001).

CONCLUSION

Patient's age was an important predictor for response after ESWL monotherapy: not only did children respond better than adults, but age was also an independent predictor within the pediatric group.

Does Previous Open Renal Stone Surgery Affect the Outcome of Extracorporeal Shockwave Lithotripsy Treatment in Adults with Renal Stones?

PURPOSE

To evaluate the effects of previous ipsilateral open renal stone surgery (ORSS) on outcomes of extracorporeal shockwave lithotripsy (SWL) in adults with renal stones.

MATERIALS AND METHODS

A total of 2097 renal units with renal stones underwent SWL treatment at our institution between March 1997 and February 2013. One thousand eight hundred thirty-nine (87.7%) of these had no history of ORSS and were categorized as group 1, and 258 (12.3%) patients having history of ipsilateral ORSS were categorized as group 2. Characteristics of patients, stone and treatment, stone-free, and complications rates were documented in detail and compared in each group. These groups were also subclassified into four subgroups according to the stone location.

RESULTS

The stone-free rates were statistically higher in group 1 than group 2 (73.2% and 61.6%, respectively). There were no differences between groups regarding the complications and steinstrasse. The stone-free rate of SWL for stones located at lower calix has significant difference according to groups 1 and 2 (64% vs 48.4%, p = 0.001). Logistic regression analysis showed that history of ORSS increased SWL failure rate 1.39 times.

CONCLUSION

Overall stone-free rates after SWL treatment was found to be significantly lower in patients with the history of ORSS than in patients without, and this finding was significantly prominent for lower calix stones. We believe that retrograde intrarenal surgery or mini- /micro-percutaneous nephrolithotripsy, despite its possible difficulties in accessing due to anatomical changes, might be a good alternative for SWL.

Comparison of intermediate- and low-frequency shock wave lithotripsy for pediatric kidney stones

The aim of the study to compare low and intermediate shock wave frequency rates in terms of success and complications for treating pediatric kidney stones. This retrospective study was performed on 58 consecutive pediatric patients (24 girls, 34 boys) who underwent shock wave lithotripsy (SWL) for kidney stones with an electrohydraulic lithotripter between April 2014 and March 2016. In the first year, all children underwent SWL with a frequency of 90 SWs/min as an intermediate frequency (Group 90), and in the second year all children were treated by SWL using 60 SWs/min as a low frequency (Group 60). The mean age of the patients was 5.87 ± 4.5 years. There were no significant differences in age, gender, stone characteristics and SWL energy level between the groups. Stone-free status was achieved in 14, 6 and 4 children in group 60; and in 10, 6 and 4 children in group 90 after one, two and three sessions, respectively. The stone-free rates were 80 and 74.1% after SWL and 90 and 88.9% after additional treatment in groups 60 and 90, respectively. The total median shock pulses were 2000 and 3600 in groups 60 and 90, respectively (p = 0.115). Efficiency quotients were 51.93 and 44.47 in groups 60 and 90, respectively. The mean total anesthesia times and complication rates did not differ between the groups. The low and intermediate frequency of SWL provided similar stone clearance in pediatric renal stones with similar anesthesia times. However, low SWL tended to need fewer shock pulses (2000/3600) for stone clearance, but the trend was not significant.

Stones in special situations

There are several special situations in which urinary lithiasis presents management challenges to the urologist. An in-depth knowledge of the pathophysiology, unique anatomy, and treatment options is crucial in order to maintain good health in these patients. In this review, we summarize the current literature on the management of the following scenarios: bladder stones, stones in bowel disease, during pregnancy, in association with renal anomalies, with skeletal deformities, in urinary diversions, and in children.

Clinical Nomograms to Predict Stone-Free Rates after Shock-Wave Lithotripsy: Development and Internal-Validation

PURPOSE

Shock-wave lithotripsy (SWL) is accepted as the first line treatment modality for uncomplicated upper urinary tract stones; however, validated prediction models with regards to stone-free rates (SFRs) are still needed. We aimed to develop nomograms predicting SFRs after the first and within the third session of SWL. Computed tomography (CT) information was also modeled for constructing nomograms.

MATERIALS AND METHODS

From March 2006 to December 2013, 3028 patients were treated with SWL for ureter and renal stones at our three tertiary institutions. Four cohorts were constructed: Total-development, Total-validation, CT-development, and CT-validation cohorts. The nomograms were developed using multivariate logistic regression models with selected significant variables in a univariate logistic regression model. A C-index was used to assess the discrimination accuracy of nomograms and calibration plots were used to analyze the consistency of prediction.

RESULTS

The SFR, after the first and within the third session, was 48.3% and 68.8%, respectively. Significant variables were sex, stone location, stone number, and maximal stone diameter in the Total-development cohort, and mean Hounsfield unit (HU) and grade of hydronephrosis (HN) were additional parameters in the CT-development cohort. The C-indices were 0.712 and 0.723 for after the first and within the third session of SWL in the Total-development cohort, and 0.755 and 0.756, in the CT-development cohort, respectively. The calibration plots showed good correspondences.

CONCLUSIONS

We constructed and validated nomograms to predict SFR after SWL. To the best of our knowledge, these are the first graphical nomograms to be modeled with CT information. These may be useful for patient counseling and treatment decision-making.

Extracorporeal shock wave lithotripsy in infants less than 12-month old

There is a lack of literature on children compared to adults regarding the long-term effects of extracorporeal shock wave lithotripsy (SWL), specifically in infants. The aim of the present study was to analyze the efficacy and safety of SWL in infants and also evaluate its potential adverse effects in the mid-term. Between May 1999 and December 2013, 36 infants with 39 renal units underwent SWL treatment for kidney stones with an electrohydraulic lithotripter (Dornier MPL 9000/ELMED Multimed Classic). All children were less than 12-month old. The mid-term effects of SWL were examined at the last follow-up by measuring arterial blood pressure, random blood glucose level and ipsilateral kidney size. Evaluation of treatment and its consequences was based on clinical examination, blood tests and conventional imaging (plain abdominal radiography and ultrasound). Overall stone-free rate was 84.6 % after 3-month follow-up without any major complications. Mid-term follow-up was available in 20 of 36 children with a mean follow-up of 3.2 ± 2.8 years (range 0.5-15.3). None of the infants were found to develop new onset of hypertension or diabetes. All treated infant kidneys' sizes were in the normal percentile range. SWL for management of infant kidney stones is effective and safe in the mid-term.

A new nomogram for prediction of outcome of pediatric shock-wave lithotripsy

INTRODUCTION

Despite the fact that shock-wave lithotripsy (SWL) remains a very good treatment option for smaller stones, it is being challenged by endourologic treatment modalities, which offer similar or even higher success rates in a shorter time, with minimal morbidity and invasiveness. The present study aimed to bring a new and practical insight in order to predict the outcomes of pediatric SWL and to provide objective information about pediatric SWL outcomes.

OBJECTIVE

To design a nomogram for predicting the outcomes of pediatric shock-wave lithotripsy.

STUDY DESIGN

The study was conducted with a retrospective design and included 402 renal units who underwent SWL between January 2009 and August 2013. Patients with known cystine stone disease and cystinuria, with internal or external urinary diversion, were excluded. Analysis was performed on 383 renal units. Postoperative imaging was performed by plain abdominal graphy and ultrasonography with 3-month intervals. Patients who were completely free of stones were considered to be a success and statistical analysis was done regardingly Multivariate analysis was conducted by logistic regression analysis and a nomogram was developed.

RESULTS

The male/female distribution was 216/167, with a mean age of 48 ± 40 months and a mean stone size of 9 ± 3.5 mm. The overall stone-free rate was 70% (270/383) and efficacy quotient was 0.57. Mean follow-up was 11 ± 11 months (3-54 months). The number of shock waves and amplitude of energy were higher in failed cases. Multivariate analysis showed that gender, stone size, number of stones, age, location of the stone, and history of previous intervention were found to be the independent prognostic factors for assessing the stone clearance rates. A nomogram was developed using these parameters. In this nomogram, the points achieved from each parameter are summed and total points correspond to the risk of failure in percent.

DISCUSSION

A previous nomogram study by Onal et al. showed that younger age (<5 years), smaller stone burden (<1 cm), absence of previous stone treatment history, single stone, pelvis or upper ureter location (in girls) were favorable prognostic factors for successful outcome. As being the first pediatric study, it had some shortcomings. The study included 381 patients within a time period of 16 years. The present study included a similar number of cases within a 4-year period, which may reflect more homogeneity of data collection. Another issue is concern about the practical use of that nomogram. It constitutes two pages, which is a limiting factor for daily use. From a statistical point of view, they performed 200 bootstrapings with the aim of internal validation, which is less than the ideal number of 1000 bootstrapings, which was performed in the present nomogram. The presented nomogram is more practical, in that the pre-operative factors can be placed on the nomogram, the points can be added up and the parents can be given the approximate percentage of predicted stone-free rate after a single session. The expected treatment modality shown to the parents and patients ought to be the least minimally invasive, have the highest success rate, the least complication rate, and show the efficacy in one procedure at a time within the shortest period. However, SWL does not completely meet these criteria. The results gained from the present critical analysis of SWL in children, which was based on a strict definition of success, showed that outcome after a single session is not that good. Therefore, defining the patients who will benefit the most became one of the main issues. A more objective and skeptical look at SWL data enabled a nomogram to be developed that brings a new and practical insight in order to predict the outcomes of pediatric SWL.

CONCLUSION

In most of the pediatric stone cases, SWL is the first-line treatment option. However, it is wise to define the patients who will benefit the most. Therefore, nomograms can be useful for this purpose. The nomogram in the present study revealed that gender, stone size, number of stones, age, location of the stone, and history of previous intervention were found to be the independent prognostic factors for assessing the stone clearance rates. This nomogram can practically be used to inform the parents, and for proper patient selection for SWL.