Trends in Imaging and Surgical Management of Pediatric Urolithiasis at American Pediatric Hospitals

Imaging trends and surgical outcomes for nephrolithiasis in the pediatric emergency department

OBJECTIVES

There has been a marked rise in the incidence of pediatric nephrolithiasis over the past two decades. Although computed tomography (CT) is the gold standard for the diagnosis of nephrolithiasis, efforts to reduce minimize childhood exposure to ionizing radiation remain important. This study aims to assess current imaging trends and rates of surgical intervention for nephrolithiasis at the hospital level.

METHODS

A multicenter, cross-sectional analysis was conducted using the Pediatric Health Information System, which included children treated in the emergency department (ED) and diagnosed with nephrolithiasis using ICD 9/10 codes from 2010 to 2021. The analysis involved a hospital-level examination where hospitals were grouped into quartiles based on their rates of CT use. Logistic regression was employed to evaluate the association between hospital-level CT utilization and rates of surgery, while accounting for demographic characteristics and treatments administered including opioids, intravenous fluids, and antibiotics.

RESULTS

We analyzed 15,979 ED visits (median age 15 years, 59 % female) across 29 hospitals. There was significant variation in CT utilizations across hospitals (range 13-91 %). Surgery rates at the index visit ranged from 5.3 to 7.5 % and rates of surgery within 6 months ranged from 15.1 to 19.1 % across hospital CT quartiles. After adjusting for demographic characteristics and treatment administered, odds of surgery occurring during the index hospitalization or within 180 days did not differ based upon hospital-level CT utilization (p-trend = 0.19 and 0.26, respectively).

CONCLUSIONS

In this hospital-level study of imaging and surgical intervention for pediatric nephrolithiasis, we found no significant association between CT utilization and rates of surgery either during the index visit or within 180 days of the ED visit. These findings suggest there are opportunities to further reduce CT usage in children presenting with nephrolithiasis.

A population-based retrospective cohort study of surgical trends and outcomes of pediatric urolithiasis in Ontario, Canada (2002-2019)

INTRODUCTION

The worldwide incidence of pediatric urinary stone disease (PUSD) is increasing. However, there is no commensurate data on whether this translates to an increasing need for surgical intervention for PUSD, given the role of conservative management.

OBJECTIVE

We aimed to evaluate the trends and outcomes of clinically significant PUSD, using administrative databases to identify patients surgically treated for PUSD.

STUDY DESIGN

This retrospective population-based cohort study assessed the incidence and trends of surgically treated PUSD and outcomes in Ontario, Canada in patients <18 years of age who underwent their first PUSD procedure between 2002 and 2019 utilizing administrative databases held at the Institute of Clinical Evaluative Sciences (ICES). We assessed the incidence of surgically treated PUSD, demographics, initial surgical treatment and imaging modality, and risk factors for repeat intervention within 5 years. Statistical analyses summarized demographics, surgical trends, and logistic regression was used to identify risk factors for repeat surgical intervention.

RESULTS

We identified 1149 patients (mean age 11.3 years), with 59.6% older than 12 years. There was a decrease in the number of PUSD procedures performed per year that was close to statistical significance (p = 0.059) and a trend towards increased utilization of ureteroscopy (URS) compared with Shockwave Lithotripsy (SWL). In addition, there was a significant increase in the proportion of females surgically treated with PUSD (p = 0.001). In the 706 patients followed for 5 years, 17.7% underwent a repeat procedure within 6 months, while 20.4% underwent a repeat procedure from 6-months to 5 years. Renal stone location (OR 2.79, 95% confidence interval (CI) 1.62-4.80, p = 0.0002) and index SWL (OR 1.66, 95% CI 1.20-2.31, p = 0.0025) were risk factors for repeat surgical intervention within the first 6-months. There was an increasing utilization of ultrasound (US) compared to computerized tomography (CT) (p = 0.0008).

DISCUSSION

Despite the literature reporting increasing PUSD incidence, we observed a non-significant decrease in the number of surgical PUSD procedures performed. Exclusion of those treated conservatively may explain our results. The increase in the proportion of females treated reflects the narrowing gender gap in stone disease. A trend towards increased URS utilization was observed and re-intervention rates were similar to previous studies.

CONCLUSION

The overall rate of surgically treated PUSD did not show an increasing trend in Ontario, Canada from 2002 to 2019. URS was the most common surgical treatment modality, with a corresponding decline in SWL rates. PUSD was associated with a high surgical re-intervention rate within 6 months.

Imaging urolithiasis: complications and interventions in children

Urolithiasis affects people in all age groups, but over the last decades there has been an increasing incidence in children. Typical symptoms include abdominal or flank pain with haematuria; in acute cases dysuria, fever or vomiting also occur. Ultrasound is considered the modality of choice in paediatric urolithiasis because it can be used to identify most clinically relevant stones. Complementary imaging modalities such as conventional radiographs or non-contrast computed tomography should be limited to specific clinical situations. Management of kidney stones includes dietary, pharmacological and urological interventions, depending on stone size, location or type, and the child's condition. With a very high incidence of underlying metabolic abnormalities and significant recurrence rates in paediatric urolithiasis, thorough metabolic evaluation and follow-up examination studies are of utmost importance.

Pediatric urolithiasis: what can pediatricians expect from radiologists?

The incidence of urolithiasis in children has increased over the two last decades. Urolithiasis formation results from urine oversaturation following insufficient water intake, urinary obstruction (notably in cases of congenital uropathies), excess production of an insoluble compound, or imbalance between crystallization promoters and inhibitors. Whereas most urolithiases in adults occur secondary to environmental factors, in children, secondary causes are far more frequent, and 15% are related to genetic causes, most often monogenic. This is especially true in recurrent forms, with early and rapid progression and bilateral stones, and in cases of familial history or consanguinity. Because of differing clinical management, one should rule out cystinuria, primary hyperoxaluria and renal tubular acidosis, among other causes of urolithiasis. As such, a complete biochemical evaluation must be performed in all cases of pediatric urolithiasis, even in cases of an underlying uropathy. Ultrasound examination is the first-line modality for imaging pediatric urolithiasis, allowing both diagnosis (urolithiasis and its complications) and follow-up. US examination should also explore clues to an underlying cause of urolithiasis. This review is focused on the role of imaging in the management and etiological assessment of pediatric urolithiasis. Radiologists play an important role in pediatric urolithiasis, facilitating diagnosis, follow-up and surgical management. A trio of clinicians (pediatric nephrologist, pediatric surgeon, pediatric radiologist) is thus necessary in the care of these pediatric patients.

Pediatric Nephrolithiasis

The prevalence of pediatric nephrolithiasis has increased dramatically in the past two decades for reasons that have yet to be fully elucidated. Workup of pediatric kidney stones should include metabolic assessment to identify and address any risk factors predisposing patients to recurrent stone formation, and treatment should aim to facilitate stone clearance while minimizing complications, radiation and anesthetic exposure, and other risks. Treatment methods include observation and supportive therapy, medical expulsive therapy, and surgical intervention, with choice of treatment method determined by clinicians' assessments of stone size, location, anatomic factors, comorbidities, other risk factors, and preferences and goals of patients and their families. Much of the current research into nephrolithiasis is restricted to adult populations, and more data are needed to better understand many aspects of the epidemiology and treatment of pediatric kidney stones.

Guideline Adherence of Paediatric Urolithiasis: An EAU Members' Survey and Expert Panel Roundtable Discussion

Background: Paediatric nephrolithiasis has increased globally, requiring standardized recommendations. This study aims to assess the paediatric urolithiasis care between EAU members along with the statements of three experts in this field. Methods: The results of an electronic survey among EAU members comparing the guideline recommendations to their current practice managing paediatric nephrolithiasis in 74 centres are contrasted with insights from an expert-panel. The survey consisted of 20 questions in four main sections: demographics, instrument availability, surgical preferences and follow-up preferences. Experts were asked to give insights on the same topics. Results: A total of 74 responses were received. Computerised Tomography was predominantly used as the main imaging modality over ultrasound. Lack of gonadal protection during operations was identified as an issue. Adult instruments were used frequently instead of paediatric instruments. Stone and metabolic analysis were performed by 83% and 63% of the respondents respectively. Conclusions: Percutaneous Nephrolithotomy is the recommended standard treatment for stones > 20 mm, 12% of respondents were still performing shockwave lithotripsy despite PNL, mini and micro-PNL being available. Children have a high risk for recurrence yet stone and metabolic analysis was not performed in all patients. Expert recommendations may guide clinicians towards best practice.

Evaluation of Preoperative Tamsulosin Role in Facilitating Ureteral Orifice Navigation for School-Age Pediatric Ureteroscopy

Purpose

To address whether preoperative tamsulosin increases the rate of successful ureteral orifice navigation for ureteroscopy (URS) without prestenting in school-age pediatric patients.

Methods

We retrospectively reviewed all pediatric patients who had undergone ureteroscopy (URS) at our institution from 2013 to 2020. Patients were divided into two groups: those who had received tamsulosin 0.4 mg daily ≥48 hours preoperatively and those who had not. Statistical analysis was done using independent-sample t-tests and Mann–Whitney U tests for continuous variables, and χ² and Fisher’s exact tests were used for categorical variables. Multivariate analysis was done using binary logistic regression test.

Results

Overall, successful ureteral orifice navigation occurred in 44 of 50 patients (88%) who had received tamsulosin and 17 of 26 (65.4%) who had not (p=0.019). On further subanalysis based on stone location and instrumentation used, successful ureteral orifice navigation had occurred in 21 of 24 patients (87.5%) in the tamsulosin group and one of five (20%) in the no-tamsulosin group for semirigid ureteroscopy for mid–distal ureterolithiasis (p=0.007). For proximal ureteral and renal stones, successful ureteral orifice navigation with a flexible ureteroscope or ureteral access sheath had occurred in 23 of 26 patients (88.5%) in the tamsulosin group and 16 of 21 (76.2%) in the no-tamsulosin group (p=0.437). Multivariate analysis showed no significant difference between success rates in the two groups after controlling for patient weight, height, BMI, and stone location. We did not observe any adverse effects from tamsulosin.

Conclusion

This is the first study to evaluate preoperative tamsulosin on successful ureteral orifice navigation in school-age pediatric patients. Although not reaching statistical significance, further evaluation should be done on larger cohorts. Patient height was found to be an independent predictor of successful ureteral orifice navigation.

Imaging modalities and treatment of paediatric upper tract urolithiasis: A systematic review and update on behalf of the EAU urolithiasis guidelines panel

BACKGROUND

Prompt diagnosis and treatment of paediatric urolithiasis are required to avoid long term sequelae of renal damage.

OBJECTIVE

To systematically review the literature regarding the diagnostic imaging modalities and treatment approaches for paediatric urolithiasis.

STUDY DESIGN

PubMed, Science Direct, Scopus and Web of Science were systematically searched from January 1980-January 2019. 76 full-text articles were included.

RESULTS

Ultrasound and Kidney-Ureter-Bladder radiography are the baseline diagnostic examinations. Non-contrast Computed Tomography (CT) is the second line choice with high sensitivity (97-100%) and specificity (96-100%). Magnetic Resonance Urography accounts only for 2% of pediatric stone imaging studies. Expectant management for single, asymptomatic lower pole renal stones is an acceptable initial approach, especially in patients with non-struvite, non-cystine stones<7 mm. Limited studies exist on medical expulsive therapy as off-label treatment. Extracorporeal shock wave lithotripsy (SWL) is the first-line treatment with overall stone free rates (SFRs) of 70-90%, retreatment rates 4-50% and complication rates up to 15%. Semi-rigid ureteroscopy is effective with SFRs of 81-98%, re-treatment rates of 6.3-10% and complication rates of 1.9-23%. Flexible ureteroscopy has shown SFRs of 76-100%, retreatment rates of 0-19% and complication rates of 0-28%. SFRs after first and second-look percutaneous nephrolithotomy (PNL) are 70.1-97.3% and 84.6-97.5%, respectively with an overall complication rate of 20%. Open surgery is seldom used, while laparoscopy is effective for stones refractory to SWL and PNL. Limited data exist for robot-assisted management.

CONCLUSIONS

In the initial assessment of paediatric urolithiasis, US is recommended as first imaging modality, while non-contrast CT is the second option. SWL is recommended as first line treatment for renal stones <20 mm and for ureteral stones<10 mm. Ureteroscopy is a feasible alternative both for ureteral stones not amenable to SWL as well as for renal stones <20 mm (using flexible). PNL is recommended for renal stones >20 mm.

Nephrolithiasis: Approach to Diagnosis and Management

Although kidney stones are less common in children than in adults, incidence in children is rising. Kidney stones may lead to significant morbidity in addition to escalating medical costs. Clinical presentation is variable. Bilateral kidney stones in a younger child should prompt work-up for primary hyperoxaluria. Metabolic abnormalities are more frequent in children and can result in frequent stone recurrence. Whole exome sequencing data shows genetic defects in about 30% of stone formers. 24 h urine collection should be conducted when patient receives his usual diet and fluid intake with normal activity. Infrared spectroscopy and X-ray diffraction are used for stone analysis. Urine studies should be delayed by 4-6 wk after stone fragmentation or treatment of any stone related complications. The goal of evaluation is to identify modifiable risk factors for which targeted therapy may be instituted. Primary indications for surgical intervention include pain, infection and obstruction. Extracorporeal shockwave lithotripsy (ESWL), ureteroscopy, and percutaneous nephrolithotomy (PCNL) are most commonly used, and selection is based on stone size, anatomy, composition and anatomy. Advances in technology have allowed a shift to minimally invasive surgeries. Comprehensive management requires multidisciplinary team. Children with kidney stones require long term follow-up with periodic assessment of stone forming activity and ascertaining stone burden. High index of suspicion should be there to diagnose diseases like primary hyperoxaluria, Dent's disease, renal tubular acidosis (RTA) etc. as these diseases have ramifications on kidney function and growth.

What predicts spontaneous passage of ≤1 cm ureteral stones in children?

PURPOSE

The aim of this study is to determine what factors predict spontaneous passage of ≤1 cm ureteral stones in children.

METHODS

Files of the patients diagnosed with a single ureteral stone on a given side between 2008 and 2017 were retrospectively reviewed. Patients with congenital obstructive uropathy, neurogenic bladder, vesicoureteral reflux and those with a stone diameter of >1 cm were excluded. Detection of ureteral stones was done using ultrasonography (US) primarily, and computed tomography when US findings were inconclusive. Patients were treated either conservatively or surgically. Conservative treatment included adequate hydration and pain management whereas surgical treatment included ureteroscopic intervention. Apart from those who required urgent intervention, patients were referred for surgical treatment after 2-4 weeks of follow-up with no spontaneous passage. Factors analyzed for association of spontaneous passage included age, gender, type of hematuria, stone localization, laterality, presence of concomitant kidney stone, degree of hydronephrosis, stone size and stone composition.

RESULTS

A total of 70 patients (38 males, 32 females); median age 4.7 years had a ≤ 1 cm ureteral stone (median diameter 7 mm). US was able to diagnose the ureteric stone in 47 patients while computed tomography was required in 23 patients. Spontaneous passage was observed in 40 patients (57.1%). Median time for stone passage was 8 days (3-34 days). Stone size and presence of hematuria (macroscopic and microscopic combined) were factors associated with spontaneous passage and 6.7 mm was found to be the cut-off (AUC = 0.953; 95% CI 0.905-1.000; sensitivity 96.7%, specificity 82.5%, p < 0.001). Moreover, age, degree of hydronephrosis or stone location were not associated with spontaneous passage.

CONCLUSION

Patients with a ureteric stone size <6.7 mm can safely be followed conservatively, with a spontaneous passage rate of 82.5%. Type of Study Case series with no comparison group. Level of Evidence IV.

Pediatric Nephrolithiasis: Risk Factors, Evaluation, and Prevention

Pediatric nephrolithiasis is a disease of increasing prevalence and economic burden, with data showing a rising trend among girls and adolescents. Kidney stones in children tend to have a high recurrence rate related to underlying risk factors, and the aim of evaluation should be to understand such causes so that targeted therapy can be provided to decrease recurrence and complications. Metabolic, anatomic, and genetic abnormalities as well as environmental risk factors have all been implicated in the pathogenesis of nephrolithiasis. Recent studies have focused on identifying monogenic causes of nephrolithiasis and/or nephrocalcinosis in young patients that would result in personalization of treatment as well as future diagnostic implications for family members. Treatment aims to decrease stone burden and recurrence as well as minimize complications and is guided by stone size and location as well as surgical expertise. Multidisciplinary care for these patients has been on the rise to provide a more comprehensive medical and surgical support. [Pediatr Ann. 2020;49(6):e262-e267.].

A clinical pathway to minimize computed tomography for suspected nephrolithiasis in children

INTRODUCTION

Ultrasound (US) imaging is preferred in the initial evaluation for children with suspected nephrolithiasis; however, computed tomography (CT) continues to be used in this setting with resultant unnecessary ionizing radiation exposure. The study institution implemented a standardized clinical pathway to reduce rates of CT utilization for children with nephrolithiasis.

OBJECTIVE

The aim of this study was to evaluate the impact of this pathway on initial imaging strategies for children with suspected nephrolithiasis.

STUDY DESIGN

A standardized pathway was designed and implemented using a systematic quality improvement process. A suspected cohort was created using 'reason for study' search terms consistent with a nephrolithiasis diagnosis. A confirmed cohort of children with a final diagnosis of nephrolithiasis was derived from this suspected cohort. The primary outcome was CT use as the initial imaging study in children with suspected or confirmed nephrolithiasis presenting to the emergency department (ED) between October 2013 and February 2018. Comparisons were made before and after pathway implementation (October 2015). Secondary outcomes included rates of CT scan within 30 days, while balancing measures included rates of admission, ED length of stay, and return visits.

RESULTS

A total of 534 children with suspected (220 prepathway; 314 postpathway) and 90 children with confirmed (37 prepathway; 53 postpathway) nephrolithiasis were included. For the suspected cohort, CT scans performed as the initial imaging evaluation (9.2% vs 2.5%, P = 0.001) and at any time during the index visit (15.7% vs 5.7%, P = 0.001) decreased after pathway implementation. Within the confirmed cohort, a non-significant decrease in initial CT rates was observed after implementation. No differences were observed in admission rates or ED length of stay after implementation. A trend toward lower return visits to the ED was seen after pathway implementation (5.5% vs 2.2%, P = 0.058).

DISCUSSION

Within a tertiary care pediatric ED associated with a strong institutional experience with clinical pathways, initial CT rates were decreased after pathway implementation for children with suspected nephrolithiasis. While retrospective assessment of suspected disease is limited, this is one of the first studies to address imaging patterns for nephrolithiasis beyond the final discharge diagnosis, thus capturing a broader cohort of children. Children with suspected nephrolithiasis can be safely managed with an US-first approach, and postvisit CT scans are rarely necessary for management.

CONCLUSIONS

A standardized clinical pathway for suspected nephrolithiasis can reduce rates of initial and overall CT utilization without adversely impacting downstream care.

Impact of the Image Gently® Campaign on Computerized Tomography Use for Evaluation of Pediatric Nephrolithiasis

PURPOSE

The Image Gently® campaign was launched by several radiological societies in 2007 to promote safe imaging in children. A goal of the campaign was to reduce ionizing radiation exposure in children. Given the recurrent nature of kidney stones, affected children are at risk for unnecessary ionizing radiation exposure from computerized tomography. We sought to determine whether the Image Gently campaign led to a decrease in the use of computerized tomography for evaluating children with nephrolithiasis. We hypothesized that the campaign was the primary cause of a reduction in the use of computerized tomography.

MATERIALS AND METHODS

We analyzed medical claims data from 2001 to 2015 identifying children with nephrolithiasis covered by the same commercial insurance provider. Using a difference in differences design, we estimated changes in computerized tomography use after the campaign started among patients less than 18 years old compared to a control group age 18 years or older with nephrolithiasis.

RESULTS

We identified 12,734 children and 787,720 adults diagnosed with nephrolithiasis. Before 2007 quarterly rates of computerized tomography use during a stone episode (per 1,000 patients) were increasing at a parallel rate in children and adults (5.1 in children vs 7.2 in adults, p = 0.123). After the Image Gently campaign started the use of computerized tomography decreased in both groups but at a slightly higher rate in adults (difference in differences 2.96, 95% CI 0.00 to 5.91, p = 0.050).

CONCLUSIONS

Although there has been a reduction in the use of computerized tomography among children with nephrolithiasis, given a similar trend seen in adults this change cannot be primarily attributed to the Image Gently campaign.

Pediatric Urinary Stone Disease in the United States: The Urologic Diseases in America Project

OBJECTIVE

To examine the recent epidemiology of pediatric urinary stone disease (USD) in the United States.

METHODS

We utilized the 2004-2016 Optum^© Clinformatics® Data Mart database, a de-identified adjudicated administrative health claims database that includes 15-18 million individuals covered annually by commercial insurance in all 50 US states. The analysis included 12,739,125 children aged 0-18 years. We calculated annual rates of USD, ambulatory visits, and procedures, and the prevalence of prescription fills.

RESULTS

The 2005-2016 USD rate was 59.5 cases per 100,000 person-years. The annual rate rose gradually from 2005 to a peak of 65.2 cases per 100,000 person-years in 2011. The USD rate increased with increasing age, and was highest among females compared to males, non-Hispanic Whites compared to other race/ethnic groups, and those residing in the South compared to other geographic regions. The overall 2005-2016 rate in the 120 days following a USD episode was 1.9 for ambulatory visits, 0.24 for surgical procedures, and 1.1 for imaging procedures. Ureteroscopy was the most common surgical procedure and CT scan was the most common imaging procedures, although ultrasound utilization increased over time. Medications were filled in 46.9% of cases, and use was lowest among males (43.1%), Asians (34.8%), and in the Northeast (34.3%). Opiate agonists were the most prevalent prescription (39.9%).

CONCLUSION

Our study provides one of the most comprehensive examinations of pediatric USD to date, demonstrating shifting rates and treatment patterns over time, as well as differences by age, gender, race/ethnicity, and geographic region.

Approaches to Eliminate Radiation Exposure in the Management of Pediatric Urolithiasis

PURPOSE OF REVIEW

Traditional management of pediatric urolithiasis has been associated with a significant amount of radiation exposure. The steady increase in pediatric urolithiasis in recent years has raised concerns of long-term consequences in this special population. This review seeks to highlight the newer insights towards eliminating radiation exposure in pediatric urolithiasis from contemporary literature.

RECENT FINDINGS

Establishing a clinical care pathway restricting usage of computed tomography in emergency rooms in suspected pediatric urolithiasis can eliminate unnecessary radiation exposure. Ultrasound can successfully replace fluoroscopy at ureteroscopy and percutaneous nephrolithotomy. Accredited technicians who use optimized settings combined with dose monitoring can significantly reduce fluoroscopic radiation. Radiation exposure in pediatric urolithiasis can be significantly reduced and potentially eliminated by employing standard protocols during workup, intervention, and follow-ups. Larger studies can support the feasibility of routinely performing ultrasound-guided surgeries instead of fluoroscopy. There is a need for development of consensus towards standardization of the management of pediatric urolithiasis.

Influence of BMI in nephrolithiasis in an Appalachian pediatric population: A single-center experience

INTRODUCTION

The prevalence of pediatric nephrolithiasis has increased significantly in the past 20 years. Metabolic abnormalities predisposing adults to nephrolithiasis in obese patients include increased urinary sodium and uric acid excretion as well as low urine pH; however, limited data are available in the pediatric population.

OBJECTIVE

The aim was to investigate whether obese pediatric patients presenting with nephrolithiasis have a unique metabolic profile similar to reported findings in obese adults with nephrolithiasis.

STUDY DESIGN

A retrospective chart review was performed in children aged 1-18 years seen at Kentucky Children's Hospital between 2010 and 2016. Inclusion criteria included all patients with documented stones confirmed by ultrasonography or computed tomography.

RESULTS

A total of 111 patient charts were reviewed in the study with a mean age of 11.8 ± 4.2 years. Seventy patients (63%) had a normal BMI and 41 patients (37%) were considered overweight/obese. There was no statistically significant relationship between BMI and stone recurrence. Obese patients had significantly decreased levels of urinary citrate, oxalate, magnesium, and potassium with significant elevations of urinary urea nitrogen, ammonia, and low urine pH compared with normal weight patients (Summary Figure).

DISCUSSION

Several groups have reported on metabolic findings within obese and non-obese pediatric patients. A Turkish study reported increased oxalate excretion and hypocitraturia in obese patients while a Korean study also reported increased rates of hypocitraturia in recurrent stone formers. Similar to these studies, we did find significant differences in citrate within our study population; however, we found significantly lower levels of urinary oxalate in obese patients. The majority of these studies do not report an association with BMI and urine pH although this has been reported in the adult population and our findings support an inverse relationship between body mass index (BMI) and pH. Our group found a higher level of calcium phosphate stones, supporting of Eisner's findings that high BMI is associated with increased supersaturation of calcium phosphate. Limitations of our study include being a single center and retrospective in nature.

CONCLUSION

Our study demonstrates differences in types of stones and urinary metabolites in an obese pediatric population suggestive of different metabolic profiles contributing to stone disease. We report similar association between BMI and urine pH, urinary potassium, and citrate. This study confirmed our primary hypothesis that obese pediatric patients would have a different urinary mineral profile as evidenced by lower levels of citrate and potassium and low urine pH; however, obese patients did not exhibit significantly elevated urinary sodium and uric acid when normalized to weight, as described in the adult population. Our study did not confirm our secondary hypothesis that stone composition would be associated with BMI status or stone recurrence.

Comparison of ultrasound versus computed tomography for the detection of kidney stones in the pediatric population: a clinical effectiveness study

BACKGROUND

The incidence of pediatric nephrolithiasis in the United States is increasing. There is a paucity of literature comparing the diagnostic performance of computed ultrasound (US) to tomography (CT) in the pediatric population.

OBJECTIVE

To determine the diagnostic performance of renal US for nephrolithiasis in children using a clinical effectiveness approach.

MATERIALS AND METHODS

Institutional review board approval with a waiver of informed consent was obtained for this retrospective, HIPAA-complaint investigation. Billing records and imaging reports were used to identify children (≤18 years old) evaluated for nephrolithiasis by both US and unenhanced CT within 24 h between March 2012 and March 2017. Imaging reports were reviewed for presence, number, size and location of kidney stones. Diagnostic performance of US (reference standard=CT) was calculated per renal unit (left/right kidney) and per renal sector (four sectors per kidney). For sector analysis, US was considered truly positive if a stone was identified at CT in the same or an adjacent sector.

RESULTS

There were 68 renal stones identified by CT in 30/69 patients (43%). Mean patient age was 14.7±3.6 years, and 35 were boys. For detecting nephrolithiasis in any kidney, US was 66.7% (48.8-80.8%) sensitive and 97.4% (86.8-99.9%) specific (positive predictive value=95.2% [77.3-99.8%], negative predictive value=79.2% [65.7-88.3%], positive likelihood ratio=26.0). Per renal sector, US was 59.7% (46.7-71.4%) sensitive and 97.4% (95.5-98.5%) specific (positive predictive value=72.3% [58.2-83.1%], negative predictive value=95.4% [93.2-96.9%], positive likelihood ratio=22.5). Of the 30 stones not detected by US, only 3 were >3 mm at CT.

CONCLUSION

In clinical practice, US has high specificity for detecting nephrolithiasis in children but only moderate sensitivity and false negatives are common.

Urology Consultation and Emergency Department Revisits for Children with Urinary Stone Disease

PURPOSE

We determined the association between urology consultation and emergency department revisits for children with urinary stones.

MATERIALS AND METHODS

This retrospective cohort study included patients 18 years old or younger who presented to an emergency department in South Carolina with a urinary stone from 1997 to 2015. The primary exposure was urology consultation during the index emergency department visit. The primary outcome was a stone related emergency department revisit occurring within 180 days of discharge from an index emergency department visit. Secondary outcomes included computerized tomography use, inpatient admission and emergent surgery.

RESULTS

Of 5,642 index emergency department visits for acute urinary stones 11% resulted in at least 1 stone related emergency department revisit within 180 days. Of revisits 59% occurred within 30 days of discharge and 39% were due to pain. The odds of emergency department revisit were highest within the first 48 hours of discharge home (OR 22.6, 95% CI 18.0 to 28.5) and rapidly decreased thereafter. Urology consultation was associated with a 37% lower adjusted odds of emergency department revisit (OR 0.63, 95% CI 0.44 to 0.90) and 68% lower odds of computerized tomography use across all emergency department visits (OR 0.32, 95% CI 0.15 to 0.69). Among patients who revisited the emergency department the frequency of pain complaints was 27% in those with a urological consultation at the index visit and 39% in those without.

CONCLUSIONS

Urology consultation was associated with decreased emergency department revisits and computerized tomography use in pediatric patients with urinary stones. Future studies should identify patients who benefit most from urology consultation and ascertain processes of care that decrease emergency department revisits among high risk patients.

Risk factors for repeat surgical intervention in pediatric nephrolithiasis: A Pediatric Health Information System database study

INTRODUCTION

Successful surgical therapy for pediatric upper urinary tract calculi (UUTC) minimizes the need for repeat surgical interventions. However, staged procedures, whether planned or unplanned, are sometimes necessary. We assessed predictors of repeat intervention for children with UUTC using a nationwide administrative dataset.

METHODS

Using the Pediatric Health Information System (PHIS) dataset, we assessed children with UUTC undergoing shock wave lithotripsy (SWL) or ureteroscopy (URS) for an index stone from January 2010 to June 2015. Primary outcome was additional treatment for nephrolithiasis within 90 days. Patient and procedural variables were assessed as potential risks for retreatment. Multivariable logistic regression models were used to compare the risk of retreatment adjusting for potential confounding factors.

RESULTS

A total of 2788 patients undergoing URS (2,216, 79.5%) and SWL (572, 20.5%) were identified. SWL, stenting at the index operation without pre-index stenting, chronic comorbidities, renal calculi, and age <5 years were independent risk factors for retreatment. Use of ureteral stenting, most commonly employed in URS, was also a strong predictor of retreatment. Odds for reintervention, adjusted by multivariate modeling, are shown in the Figure.

CONCLUSIONS

Adjusting for measured confounders, SWL is associated with a 2.6-fold higher risk of repeat stone-related interventions. Additional patient-related factors also increase likelihood of retreatment. Intra-operative stent placement is a strong predictor of retreatment, perhaps serving as a marker for complex cases or planned staged procedures. Prospective studies are needed to assess comparative effectiveness of SWL and URS and improve mono-therapeutic success for children with UUTC.

Pediatric hospitalizations for upper urinary tract calculi: Epidemiological and treatment trends in the United States, 2001-2014

INTRODUCTION

The incidence of urolithiasis in the pediatric population in the United States has steadily been increasing over the past few decades. Few studies to date have examined trends in the hospitalization and inpatient surgical treatment of urolithiasis in the pediatric population using nationally representative data.

OBJECTIVE

The aim was to evaluate nationwide trends in the rates of pediatric hospitalization and inpatient surgical activity for upper urinary tract calculi (UUTC) in the United States from 2001 to 2014.

PATIENTS AND METHODS

The National Inpatient Sample (NIS) databases for 2001-2014 were queried. Hospitalizations for patients younger than age 18 (excluding newborns), with principal discharge diagnoses of kidney or ureteral calculi were selected. Surgical procedures during hospitalization were identified. Hospitalization and surgical activity data were analyzed using trends tests, chi-square statistics, and multivariable logistic regression as appropriate.

RESULTS

Of an estimated 30.2 million pediatric hospitalizations during the study period, 44,369 overall (147 per 100,000) were for UUTC. The total number and proportion of UUTC hospitalizations per 100,000 all-cause admissions significantly decreased between 2001 and 2014 (p < 0.0001) (figure). Surgical intervention was undertaken in 19,946 (45%) of UUTC hospitalizations, with significantly increasing frequency over the study interval (p < 0.0001). Urinary tract drainage was the most frequently performed surgical intervention. On multivariable analysis, significant predictors of a higher likelihood of undergoing inpatient surgical intervention during hospitalization for UUTC included older age, female gender, deficiency anemias, hypertension, neurologic disorders, paralysis, and hospitalization after 2001.

DISCUSSION

The declining trend in hospitalization for UUTC likely reflects a shift toward outpatient care for routine cases, reserving hospitalization for sicker patients or those with complications of urolithiasis. Similar to previous studies, we also observed that girls were significantly more likely than boys to be hospitalized for stone disease, and that majority of the stone activity in the pediatric population was in children aged 15-17 years. We also observed a sharp increase in the proportion of hospitalized patients who underwent surgical intervention between 2001 and 2014, but the primary driver of this trend remains uncertain.

CONCLUSION

Pediatric hospitalizations for UUTC in US children significantly decreased between 2001 and 2014, while of those hospitalized the proportion who underwent stone-related surgical intervention significantly increased over the same period. A shift towards outpatient care, reserving hospitalization and inpatient surgical care for sicker patients, those with urolithiasis-related complications, or those who fail conservative management, is a possible explanation for these observed trends.

Increasing Prevalence of Nephrolithiasis in Association with Increased Body Mass Index in Children: A Population Based Study

PURPOSE

Epidemiological studies demonstrate an association of increased body mass index and risk of kidney stone formation in adults. We conducted a population based pediatric study to examine the epidemiology of nephrolithiasis in Israeli children during a 30-year period, and to determine body mass index distribution during the same period.

MATERIALS AND METHODS

We accessed data from the compulsory medical evaluations of 17-year-old military service candidates in Israel before their enlistment during 1980 to 2013. Candidates for the army with a history of stone disease were compared to those without such a history.

RESULTS

Of 1,908,893 candidates 1,691 reported a history of nephrolithiasis, yielding an average prevalence rate of 88.6 per 100,000. During 1980 to 1995 the average reported prevalence of nephrolithiasis was 69 cases per 100,000. From 1995 onward the reported prevalence increased by an average of 6% yearly, reaching 120 per 100,000 during 2010 to 2012. This increased prevalence was observed for males and females but was more prominent among males. Mean ± SD body mass index of stone formers was higher than that of controls (22.7 ± 3.5 vs 22.1 ± 3.9 kg/m², p <0.001). The trend of increasing body mass index among male candidates during 1995 to 2012 parallels the trend of increasing nephrolithiasis during these years. The odds ratio for nephrolithiasis in candidates with body mass index 30 or greater kg/m² was 1.7 (range 1.4 to 2.1) compared to candidates with a body mass index of 18.5 to 24.9 kg/m².

CONCLUSIONS

This large, population based study documents an increasing prevalence of nephrolithiasis in children. The possible association of this finding with the increase in body mass index during the same period warrants further investigation.

Use of medical expulsive therapy in children: An assessment of nationwide practice patterns and outcomes

INTRODUCTION

Early data support the use of medical expulsive therapy (MET) in children. However, little is known regarding use or outcomes associated with MET outside of pediatric-specific practices. Using a national administrative dataset, we sought to characterize utilization patterns of MET as well as assess outcomes associated with MET exposure.

STUDY DESIGN

We interrogated the MarketScan Commercial Claims and Encounters database to identify children under the age of 18 presenting to the emergency department (ED) with any diagnosis of upper urinary tract calculi (UUTC, including renal and ureteral calculi). MET exposure was defined as having a prescription filled for a MET agent within 1 week of the ED encounter. Characteristics of children receiving MET were defined and outcomes compared between children with and without MET exposure.

RESULTS

Of 1325 children included in the study, 13.2% received MET, including 15.4% of children with a diagnosis of "calculus of the ureter." MET use increased significantly throughout the study period (p = 0.004), although only 30.4% of children considered potential MET candidates received MET in the final year of the study (2013). Among all patients, receipt of MET was associated with male gender, presence of comorbidity, provider-type (urologist), and year of diagnosis, although among those with a specific diagnosis of "calculus of the ureter," only year of diagnosis remained a significant factor. Rates of unplanned physician visits and surgical interventions were similar between groups. Children receiving MET were more likely to receive follow-up imaging, although only 46% of children with ureteral calculi had appropriate follow-up imaging within 90 days, regardless of MET exposure. Odds ratios of factors and outcomes associated with MET exposure are shown in the Table.

DISCUSSION

Although early data support safety and efficacy MET in children, nationwide use in children is low among potential candidates for MET. For children with ureteral calculi, only year of diagnosis was a significant factor associated with MET use. No difference in unplanned physician visits or surgical interventions was noted. Most notable, however, was the low rate of follow-up imaging within 90 days for children presenting acutely with UUTC.

CONCLUSIONS

Use of MET for children with ureteral calculi is increasing, although still fewer than a third of children considered potential candidates receive this treatment. Follow-up imaging is not obtained for many children with ureteral calculi. Future work is needed to standardize management and follow-up protocols for children with acute renal colic.

Infant nephrolithiasis and nephrocalcinosis: Natural history and predictors of surgical intervention

INTRODUCTION

Renal stone disease diagnosed in the first year of life is relatively uncommon. While risk factors such as low birth weight, furosemide exposure, and metabolic disorders are well established, there exists little information regarding resolution rates and need for surgical intervention. Our study objective was to evaluate urolithiasis and renal calcification resolution rates, time to resolution, and need for surgical intervention in children diagnosed in their first year of life.

MATERIAL AND METHODS

REB approved retrospective chart review of children younger than 12 months of age (corrected for prematurity) diagnosed with nephrolithiasis and/or nephrocalcinosis in a tertiary pediatric hospital between April 2000 and August 2015 with a minimum 1-year follow-up period. Exact logistic regression was performed to assess the relationship between size of the largest stone (on either side) and the need for surgical intervention. Kaplan-Meier curves were constructed to examine time to stone resolution among those not requiring surgical intervention.

RESULTS

62 patients (61% male) were diagnosed with stones or nephrocalcinosis by ultrasound at a median age of 2.9 months. Of these, 37% had been admitted to the NICU because of prematurity, low birth weight or comorbidities. A total of 45 patients were found to have stones (Table); 35 of these had a stone at initial ultrasound and 10 initially diagnosed as nephrocalcinosis were later confirmed to have a stone. 67% of all stones were asymptomatic on presentation. Metabolic anomalies were present in 56% (35/62), and 16% (10/62) required medical treatment. Seven patients ultimately required surgical intervention. Stone size was found to predict the eventual need for surgical intervention (OR 3.52, 95% CI 1.47-12.78) for each 0.1 mm increase in diameter). Among patients not requiring surgical intervention (n = 38), the estimated median time to spontaneous resolution of urolithiasis was 1.1 years (95% CI 0.89-1.53, range 2 months-6 years) and 1.2 years for nephrocalcinosis (95% CI 0.59-2.13).

CONCLUSIONS

Spontaneous resolution was a common outcome for newborns and infants diagnosed with urolithiasis in the first year of life, but high variability in time-to-resolution was observed. Only a small proportion who had confirmed stones on ultrasound required surgical intervention (15%), and large stone size was a predictive factor for surgery.

Silodosin in the treatment of distal ureteric stones in children: A prospective, randomised, placebo-controlled study

Objectives

To evaluate the possible role of silodosin (a highly selective α_1A-adrenoceptor antagonist) in facilitating the passage of distal ureteric stones (DUS) in children, as the role of α-blockers as medical expulsive therapy is well known in adults.

Patients and methods

In all, 40 paediatric patients (27 boys and 13 girls) diagnosed with unilateral, single, radiopaque DUS of <10 mm were included in the study. Their mean (SD, range) age was 8.1 (2.7, 5–17) years. The patients were randomly divided into two groups: Group A, received silodosin 4 mg as a single bedtime dose; and Group B, received placebo as a single bedtime dose. Ibuprofen was prescribed to both groups on-demand for pain episode relief. Patients were followed up biweekly for 4 weeks. The stone expulsion time and rate, pain episodes, analgesic use, and any adverse effects were recorded.

Results

The mean (SD) stone size in Group A was 6.6 (1.7) mm and in Group B was 6.7 (1.4) mm (P = 0.4). Two patients were lost to follow-up (one from each group), and one patient in Group A refused to complete the study. The stone-free rate at end of the 4-week treatment period was 88.8% in Group A vs 73.6% in Group B (P = 0.4). The mean (SD) stone expulsion time was 7.0 (4.3) vs 10.4 (4.7) days in groups A and B, respectively (P = 0.02). The mean (SD) number of pain episodes requiring ibuprofen was 2.3 (1.4) vs 4.7 (2.6) episodes in groups A and B, respectively (P < 0.001). Adverse effects (headache and dizziness) were recorded in three patients (16.7%) in Group A, which were mild and none of them discontinued treatment, whilst no adverse effects were recorded in Group B.

Conclusions

The data in the present study show that silodosin can be safely used in the treatment of DUS in children for decreasing time to stone expulsion, pain episodes, and analgesic requirement.

Pediatric Nephrolithiasis: A Review

The incidence of pediatric nephrolithiasis is on the rise. The composition of kidney stones in children is different than in adults, as most stones in children have a composition of calcium oxalate and calcium phosphate mixed with a small amount of uric acid. The symptoms of pediatric nephrolithiasis are nonspecific. Computed tomography (CT) is the gold standard for diagnosis; however, because of radiation exposure associated with a CT scan, ultrasonography is also an accepted modality for the diagnosis. Extensive metabolic evaluation is important to rule out an underlying metabolic disorder. Urinary decompression, medical expulsion therapy, and surgical interventions such as ureteroscopy and extracorporeal shockwave lithotripsy are some of the options available for treating pediatric nephrolithiasis. [Pediatr Ann. 2017;46(6):e242-e244.].

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.

Imaging in the diagnosis of pediatric urolithiasis

Pediatric urolithiasis is an important and increasingly prevalent cause of pediatric morbidity and hospital admission. Ultrasound (US) is the recommended primary imaging modality for suspected urolithiasis in children. There is, however, widespread use of CT as a first-line study for abdominal pain in many institutions involved in pediatric care. The objective of this review is to outline state-of-the-art imaging modalities and methods for diagnosing urolithiasis in children. The pediatric radiologist plays a key role in ensuring that the appropriate imaging modality is performed in the setting of suspected pediatric urolithiasis. Our proposed imaging algorithm starts with US, and describes the optimal technique and indications for the use of CT. We emphasize the importance of improved communication with a greater collaborative approach between pediatric and general radiology departments so children undergo the appropriate imaging evaluation.

Clinical effectiveness in the diagnosis and acute management of pediatric nephrolithiasis

The incidence of pediatric nephrolithiasis has risen over the past few decades leading to a growing public health burden. Children and adolescents represent a unique patient population secondary to their higher risks from radiation exposure as compared to adults, high risk of recurrence, and longer follow up time given their longer life expectancies. Ultrasound imaging is the first-line modality for diagnosing suspected nephrolithiasis in children. Although data is limited, the best evidence based medicine supports the use of alpha-blockers as first-line MET in children, especially when stones are small and in a more distal ureteral location. Surgical management of pediatric nephrolithiasis is similar to that in adults with ESWL and URS first-line for smaller stones and PCNL reserved for larger renal stone burden. Clinical effectiveness in minimizing risks in children and adolescents with nephrolithiasis centers around ED pathways that limit CT imaging, strict guidance to ALARA principles or use of US during surgical procedures, and education of both patients and families on the risks of repeat ionizing radiation exposures during follow up and acute colic events.

Pediatric emergency medicine point-of-care ultrasound: summary of the evidence

The utility of point-of-care ultrasound is well supported by the medical literature. Consequently, pediatric emergency medicine providers have embraced this technology in everyday practice. Recently, the American Academy of Pediatrics published a policy statement endorsing the use of point-of-care ultrasound by pediatric emergency medicine providers.  To date, there is no standard guideline for the practice of point-of-care ultrasound for this specialty. This document serves as an initial step in the detailed "how to" and description of individual point-of-care ultrasound examinations.  Pediatric emergency medicine providers should refer to this paper as reference for published research, objectives for learners, and standardized reporting guidelines.

The Modern Metabolic Stone Evaluation in Children

OBJECTIVE

To evaluate metabolic abnormalities in a contemporary pediatric population after their first stone episode. The incidence of pediatric nephrolithiasis is increasing and therefore the etiologies contributing to today's pediatric stone formation may also be changing.

MATERIALS AND METHODS

A retrospective review of all consecutive children presenting after their first kidney stone between 2000 and 2014 was performed. We compared demographic data, serum chemistry results, and 24-hour urine results and treatments.

RESULTS

One hundred thirteen children with a mean age of 11 years (5 months to 18 years) who presented with their first kidney stone episode between 2000 and 2014 were evaluated. Sixteen patients (14%) were found to have an underlying genetic or systemic disease. Overall, there was a low rate of serum chemistry abnormalities. The most common abnormalities found within the 24-hour urine evaluation included low urine volume (89%) and hypocitraturia (68%). Hypercalciuria occurred rarely (11%).

CONCLUSION

We identified a low rate of underlying genetic or systemic diseases contributing to modern pediatric stone presentation and an increased proportion of idiopathic stones. Our study differs from historical findings by identifying a low rate of hypercalciuria and a high rate of low urine volume and hypocitraturia, suggestive of changing metabolic abnormalities contributing to modern pediatric stone disease.

Is the Economic Impact and Utilization of Imaging Studies for Pediatric Urolithiasis Across the United States Increasing?

OBJECTIVE

To identify longitudinal trends of economic impact and resource utilization for management of pediatric urolithiasis using national databases.

METHODS

We analyzed the 2006-2012 Nationwide Emergency Department Sample and Nationwide Inpatient Sample. We used ICD-9 (International Classification of Diseases) codes to identify patients (≤18 years) diagnosed with urolithiasis. Diagnostic imaging and surgeries were identified using ICD-9 and Current Procedural Technology codes. We abstracted demographic, imaging, procedure, and charge data. Weighted descriptive statistics were calculated to describe the population's demographics and economic expenditures by clinical setting and year.

RESULTS

In total, 45,333 inpatient admissions (68% females) and 234,559 emergency department encounters (63% females) were identified. Most patients (84%) were teenagers and the southern region of the United States was the most common geographic region for all encounters (44%). There was no significant trend in number of urolithiasis encounters over the period studied. Utilization of all imaging techniques increased; in particular, computed tomography was used in 23% of encounters in 2006 and 40% in 2012 (P < .0001). The mean charge per emergency department visit increased by 60% from $3645 in 2006 to $5827 in 2012 (P < .0001). The mean charge increased for inpatient admissions by 102%, from $16,399 in 2006 to $33,205 in 2012 (P < .0001). Total charges increased 72% over the study period from $230 million in 2006 to $395 million in 2012 (P < .0001), outpacing medical inflation over the same period.

CONCLUSION

Charges for pediatric urolithiasis management increased by 65% from 2006 to 2012 despite stable frequency of patient encounters. The utilization of computerized tomography in pediatric urolithiasis increased as well.

Imaging and surgical utilization for pediatric cystinuria patients: A single-institution cohort study

OBJECTIVE

Although cystinuria is rare, its clinical manifestations are life-long. Little is known about healthcare utilization in this population.

STUDY DESIGN

Through billing records and chart review, we identified pediatric patients with cystinuria treated at our institution. Variables included demographics, gender, race, comorbidities, location of presentation, presenting symptoms, initial laboratory data, and stone characteristics. Outcomes included the number and type of imaging tests and procedures performed. Descriptive statistics were performed. Median annual frequencies of procedures and imaging were calculated.

RESULTS

Twenty-three patients who presented between 1995 and 2011 were identified. The median age at presentation was 12 years, 48% of our patients were male, and 91% were Caucasian. Median follow-up was 4.6 years. Over half were diagnosed in clinic (13/23), while 30% (7/23) presented to the ED. Pain was the most common presenting symptom (13/23), followed by nausea/vomiting (6/23), gross hematuria (5/23), and fevers (5/23). Only one patient presented with acute renal failure. Five patients were discovered by sibling screening. The median number of stones at presentation was two and median size of the largest stone was 9 mm, with three staghorn calculi. During follow-up, a total of 110 stone procedures were performed in 15 patients. Five patients underwent 13 PCNLs, 11 patients underwent 44 ureteroscopy procedures, and nine underwent open or robotic surgery, including one nephrectomy. Among patients identified by sibling screening, most (4/5) were managed with medical therapy alone. A total of 390 imaging procedures were performed. Radiation-associated imaging comprised half of all imaging tests.

DISCUSSION

The high rates of imaging and surgical utilization among pediatric cystinuria patients reflect the morbidity of this condition and the need for preventative management. By practicing the ALARA principle during urologic procedures, urologists can reduce radiation exposure. Multiple procedures are often required to render patients stone-free. URS/LL and PCNL are likely to be more effective than ESWL. In complex cases, robotic-assist lithotomy provides the advantage of a minimally invasive approach. Both sibling screening and transitional care represent long-term strategies with the potential to reduce life-long morbidity. The limitations of this study include its small sample size, retrospective nature, and single-center experience.

CONCLUSIONS

Our study demonstrates that the clinical impact of disease among pediatric patients presenting with cystinuria at our institution is considerable, with most requiring surgery. Our population also generates heavy utilization of diagnostic imaging. Given the lifelong nature of this disease, research on improved preventive therapies is urgently needed.

Pediatric Kidney Stones - Avoidance and Treatment

Pediatric stone disease is increasing in incidence and healthcare costs. With more years at-risk for stone recurrence during their lifetimes, children with nephrolithiasis constitute a high-risk patient population that requires focused intervention through both medical and surgical means. Through high-quality future studies to compare methods of stone prevention and treatment, the burden of stone disease on the youngest members of society may be ameliorated.

Annual Incidence of Nephrolithiasis among Children and Adults in South Carolina from 1997 to 2012

BACKGROUND AND OBJECTIVES

The prevalence of nephrolithiasis in the United States has increased substantially, but recent changes in incidence with respect to age, sex, and race are not well characterized. This study examined temporal trends in the annual incidence and cumulative risk of nephrolithiasis among children and adults living in South Carolina over a 16-year period.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a population-based, repeated cross-sectional study using the US Census and South Carolina Medical Encounter data, which capture all emergency department visits, surgeries, and admissions in the state. The annual incidence of nephrolithiasis in South Carolina from 1997 to 2012 was estimated, and linear mixed models were used to estimate incidence rate ratios for age, sex, and racial groups. The cumulative risk of nephrolithiasis during childhood and over the lifetime was estimated for males and females in 1997 and 2012.

RESULTS

Among an at-risk population of 4,625,364 people, 152,925 unique patients received emergency, inpatient, or surgical care for nephrolithiasis. Between 1997 and 2012, the mean annual incidence of nephrolithiasis increased 1% annually from 206 to 239 per 100,000 persons. Among age groups, the greatest increase was observed among 15-19 year olds, in whom incidence increased 26% per 5 years (incidence rate ratio, 1.26; 95% confidence interval, 1.22 to 1.29). Adjusting for age and race, incidence increased 15% per 5 years among females (incidence rate ratio, 1.15; 95% confidence interval, 1.14 to 1.16) but remained stable for males. The incidence among blacks increased 15% more per 5 years compared with whites (incidence rate ratio, 1.15; 95% confidence interval, 1.14 to 1.17). These changes in incidence resulted in doubling of the risk of nephrolithiasis during childhood and a 45% increase in the lifetime risk of nephrolithiasis for women over the study period.

CONCLUSIONS

The incidence of kidney stones has increased among young patients, particularly women, and blacks.

Tracking of radiation exposure in pediatric stone patients: The time is now

BACKGROUND

Despite the increasing incidence of pediatric nephrolithiasis, there is little data quantifying the radiation exposure associated with treatment of this disease. In this study, pediatric patients with nephrolithiasis who were managed at a single institution were identified, and the average fluoroscopy time and estimated radiation exposure associated with their procedures were reported.

METHODS

Stone procedures performed on pediatric patients between 2005 and 2012 were retrospectively identified. Procedures were classified as primary ureteroscopy (URS), stent placement prior to ureteroscopy (SURS), percutaneous nephrolithotomy (PCNL), and bilateral ureteroscopy (BLURS). Patient demographic information, stone size, stone location, number of radiographic images, and fluoroscopy times were analyzed.

RESULTS

A total of 152 stone procedures were included in the final analysis (92 URS, 38 SURS, eight BLURS and 14 PCNL). Mean patient age at time of stone treatment was 15.94 ± 4.1 years. Median fluoroscopy times were 1.6 (IQR 0.8-2.4), 2.1 (IQR 1.6-3.0), 2.5 (IQR 2.0-2.9), and 11.7 (IQR 5.0-18.5) minutes for URS, SURS, BLURS and PCNL, respectively. There was a moderate correlation between stone size and fluoroscopy time (r = 0.33). When compared with ureteroscopic procedures, PCNL was associated with a significantly higher fluoroscopy time (11.7 vs 2.1 min, P < 0.001). The estimated median effective dose was 3 mSv for ureteroscopic procedures and 16.8 mSv for PCNL. In addition to radiation exposure during treatment, patients in this cohort were exposed to an average of one (IQR1-3) CT scan and three (IQR 1-8) abdominal X-rays. No new malignancies were identified during the limited follow-up period.

CONCLUSIONS

Radiation exposure during treatment of pediatric stone disease is not trivial, and is significantly greater when PCNL is performed. Given the recommended maximum effective dose of 50 mSv in any one year, urologists should closely monitor the amount of fluoroscopy used, and consider the potential for radiation exposure when choosing the operative approach. Prospective studies are currently underway to elucidate precise dose measurements and localize sites of radiation exposure in children during stone treatment.

Medical expulsive therapy for pediatric urolithiasis: Systematic review and meta-analysis

OBJECTIVE

Kidney stone disease has become more common among children and young adults. Despite its well-documented success in adults, published success rates of medical expulsive therapy (MET) for pediatric urolithiasis vary widely. Our objective was to determine whether the aggregated evidence supports the use of MET in children.

METHODS

We searched the Cochrane Controlled Trials Register, clinicaltrials.gov, MEDLINE, and EMBASE databases, and recently presented meeting abstracts for reports in any language. In addition, the bibliographies of included studies were then hand-searched. The protocol was prospectively registered at PROSPERO (CRD42013005960). Inclusion criteria were children (aged ≤ 18 years) with urolithiasis treated with medications with the specific goal of increasing spontaneous stone passage rate, including but not limited to alpha-adrenergic blockers (e.g., tamsulosin or doxazosin), calcium channel blockers (e.g., nifedipine), or other adjuvant medications (e.g., steroids or tolterodine). Manuscripts were then assessed and data abstracted in duplicate, with differences resolved by the senior author. Risk of bias was assessed using standardized instruments. Descriptive statistical analyses were performed as appropriate.

RESULTS

We identified 11,197 studies, five of which (3 randomized controlled trials, 2 retrospective cohorts) were included in the pooled meta-analysis. Although we found little evidence of significant publication bias, we were unable to assess the likelihood of other forms of bias (allocation, selection) for most included studies due to reporting limitations. The pooled results demonstrate that MET significantly increased the odds of spontaneous stone passage (OR 2.21, 95% CI 1.40-3.49). Between-study heterogeneity was not statistically significant (I(2) = 14%, p = 0.36). Bivariate meta-regression models revealed no significant association between the likelihood of stone passage and study COI (p = 0.9), study country (p = 0.7), patient age (p = 0.4), patient gender (p = 0.4), duration of follow-up (p = 0.3), or stone size (p = 0.7). Side effects of MET were reported to be minimal. Relatively few patients reported any adverse effects at all; the most commonly reported issue was somnolence. Concerns about biases affecting the published outcomes of the included studies exist due to the low quality of the randomized controlled trials reviewed for analysis. However, there was little visual evidence of publication bias noted on the funnel plot, as confirmed by the Begg test (p = 0.5).

CONCLUSIONS

Consistent with the adult literature, pediatric studies demonstrate that treatment with MET results in increased odds of spontaneous ureteral stone passage and a low rate of adverse events. Although the accumulated literature is limited by inconsistent and/or incomplete reporting, there is nonetheless a clear, cumulative positive effect of MET on stone passage among children. The available evidence thus supports a prominent role for MET in treatment algorithms for pediatric urolithiasis.

Ureteroscopy for Paediatric Renal Tract Stones - Outcomes from a Tertiary European Centre

Aims: The use of ureteroscopy in treating paediatric stone disease has risen in recent years. We retrospectively reviewed the results of ureteroscopic stone management for our regional paediatric stone service. Material and Methods: Between April 2010 and October 2013, consecutive patients undergoing ureteroscopy and stone fragmentation were identified. Data were recorded from electronic records for patient demographics, pre-operative assessment, stone characteristics, and intra- and post-operative complications. Results: Twenty-one patients (mean age 8.6 years; range: 1.4-16) had 32 procedures in our series (13 males and 8 females). Five (24%) had a metabolic abnormality and 8 (38%) had an anatomical abnormality. The mean initial stone size was 9.6 mm (range: 5-20) and 10 were left sided. Of the 32 procedures, 18 (56%) had a pre-operative stent. A positive pre-operative urine culture was seen in 4 (13%). CT was used in 6 (19%) with the rest having a combination of USS and/or plain KUB. Of these 21 patients, 13 (62%) were stone free after the first procedure, 17 (81%) after a second and 20 (95%) after a third (mean 1.5 procedures/patient). One patient with a 6-mm residual fragment chose to have surveillance. Eighteen (50%) had post-operative stent insertion. The mean length of stay was 1.5 days (range: 0-5). A minor complication (Clavien 1) was observed in 1 patient. No other complications were recorded. Conclusions: Ureteroscopy for stone disease in children is feasible with a low complication rate and high stone-free rate.

Use of and regional variation in initial CT imaging for kidney stones

OBJECTIVE

We sought to determine the prevalence of initial computed tomography (CT) utilization and to identify regions in the United States where CT is highly used as the first imaging study for children with nephrolithiasis.

METHODS

We performed a cross-sectional study in 9228 commercially insured children aged 1 to 17 years with nephrolithiasis who underwent diagnostic imaging in the United States between 2003 and 2011. Data were obtained from MarketScan, a commercial insurance claims database of 17,827,229 children in all 50 states. We determined the prevalence of initial CT use, defined as CT alone or CT performed before ultrasound in the emergency department, inpatient unit, or outpatient clinic, and identified regions of high CT utilization by using logistic regression.

RESULTS

Sixty-three percent of children underwent initial CT study and 24% had ultrasound performed first. By state, the proportion of children who underwent initial CT ranged from 41% to 79%. Regional variations persisted after adjusting for age, gender, year of presentation, and insurance type. Relative to children living in West South Central states, the highest odds of initial CT utilization were observed for children living in the East South Central US Census division (odds ratio: 1.27; 95% confidence interval: 1.06-1.54). The lowest odds of initial CT were observed for children in the New England states (odds ratio: 0.48; 95% confidence interval: 0.38-0.62).

CONCLUSIONS

Use of CT as the initial imaging study for children with nephrolithiasis is highly prevalent and shows extensive regional variability in the United States. Current imaging practices deviate substantially from recently published guidelines that recommend ultrasound as the initial imaging study.

Nationwide emergency department imaging practices for pediatric urolithiasis: room for improvement

PURPOSE

Children are particularly vulnerable to the harmful effects of medical radiation, and children with urolithiasis comprise a group that may undergo repeated radiation intensive imaging tests. We sought to characterize imaging practices for children presenting to the emergency department with suspected urolithiasis and to determine factors associated with the choice of imaging study.

MATERIALS AND METHODS

Using the 2006 to 2010 Nationwide Emergency Department Sample, we conducted a retrospective cohort study of patients younger than 18 years presenting with suspected urolithiasis. We determined imaging practices for visits to emergency departments where billing codes for computerized tomography and ultrasound were reliably reported. Logistic regression was used to delineate patient and hospital level factors associated with the use of computerized tomography vs ultrasound.

RESULTS

We identified 18,096 pediatric visits for suspected urolithiasis in the 1,191 Nationwide Emergency Department Sample emergency departments with reliable imaging codes. A total of 11,215 patients underwent computerized tomography alone, ultrasound alone or both. Of the patients 9,773 (87%) underwent computerized tomography alone. Computerized tomography use peaked in 2007 and declined thereafter. On multivariate analysis several factors were associated with the use of computerized tomography alone, including smaller proportion of pediatric patients treated at the emergency department, older age, location in the Midwest or South, evaluation at a nonteaching hospital and visit on a weekend.

CONCLUSIONS

Computerized tomography use is highly prevalent for children presenting with suspected urolithiasis. The lowest computerized tomography use is in emergency departments that care for more children. Ultrasound is used infrequently regardless of site. Awareness regarding risks of computerized tomography and consideration of alternatives including ultrasound are warranted in caring for these patients.

American and Brazilian Children With Primary Urolithiasis: Similarities and Disparities

Objectives. Considering the differences in location, socioeconomic background, and cultural background, the aim of this study was to try to identify possible factors associated with the increased incidence of urolithiasis by comparing American and Brazilian children with stones. Methods. Data of 222 American and 190 Brazilian children with urolithiasis were reviewed including age, gender, body mass index, imaging technique used (ultrasound and computed tomography), and 24-hour urine volume and chemistries. Results. There were no differences between age and gender at diagnosis. Brazilian children were leaner but in no population did obesity rate exceed that of the general population. Ultrasound was most commonly used to diagnose stones, even more so in Brazilians. Decreased urine flow was more common among Americans (P = .004), hypercalciuria among Brazilians (P = .001), and elevated Ca/citrate ratio among Americans (P = .009). There were no differences between the groups in the frequency of hypocitraturia, hyperuricosuria, absorptive hyperoxaluria, and cystinuria. Conclusions. Despite some differences between the populations, the leading causes of urolithiasis among both were “oliguria,” hypercalciuria, and high Ca/citrate ratio. In neither country was obesity the reason for the increase in incidence of urolithiasis, nor was the use of computed tomography. The similarities between the 2 populations call for combining efforts in addressing the leading causes of pediatric urolithiasis.

Pediatric primary urolithiasis: 12-year experience at a Midwestern Children's Hospital

PURPOSE

Due to environmental and social changes (and possibly obesity) as new risk factors for stone formation in adults and changes in imaging techniques, we assessed whether etiologies of primary pediatric urolithiasis have changed, and if relationships exist between the condition and obesity or imaging technique.

MATERIALS AND METHODS

All pediatric patients with documented primary urolithiasis who underwent serum and 24-hour urine analyses between 1999 and 2010 were evaluated. Age at diagnosis, gender, body mass index and imaging technique were recorded.

RESULTS

Of the 222 patients (48% male) all had normal serum creatinine, electrolytes and minerals. Primary pediatric urolithiasis was diagnosed by ultrasound in 73% of cases and computerized tomography in 27%. Mean ± SD annual incidence of urolithiasis per 1,000 clinic visits increased from 2.4 ± 1.5 in the first half of the study period to 6.2 ± 2.1 in the second half (p <0.005). Mean ± SD age at diagnosis was 11.8 ± 3.8 years and body mass index was 21.7 ± 5.7 (rate of overweight 15%). A total of 140 patients had urine output less than 1.0 ml/kg per hour, with this being the only abnormality in 54. Hypercalciuria was observed in 46% of patients, hypocitraturia in 10% and high calcium-to-citrate ratio in 51%. Mild absorptive hyperoxaluria was noted in 3 patients and hyperuricosuria in 11, with all 14 exhibiting at least 1 additional abnormality. Cystinuria was present in 1 patient. No etiology was identified in 20 patients (9.0%).

CONCLUSIONS

Oliguria and hypercalciuria continue to be the most common etiologies of pediatric primary urolithiasis, followed by hypocitraturia. The recent increase in stone incidence is unlikely due to increased use of computerized tomography. Incidence of obesity was not higher than in the general population. Hyperoxaluria and cystinuria are rare, and thus might not be indicated in the initial analysis.

Temporal trends in incidence of kidney stones among children: a 25-year population based study

PURPOSE

We conducted a population based pediatric study to determine the incidence of symptomatic kidney stones during a 25-year period and to identify factors related to variation in stone incidence during this period.

MATERIALS AND METHODS

The Rochester Epidemiology Project was used to identify all patients younger than 18 years who were diagnosed with kidney stones in Olmsted County, Minnesota from 1984 to 2008. Medical records were reviewed to validate first time symptomatic stone formers with identification of age appropriate symptoms plus stone confirmation by imaging or passage. The incidence of symptomatic stones by age, gender and study period was compared. Clinical characteristics of incident stone formers were described.

RESULTS

A total of 207 children received a diagnostic code for kidney stones, of whom 84 (41%) were validated as incident stone formers. The incidence rate increased 4% per calendar year (p = 0.01) throughout the 25-year period. This finding was due to a 6% yearly increased incidence in children 12 to 17 years old (p = 0.02 for age × calendar year interaction) with an increase from 13 per 100,000 person-years between 1984 and 1990 to 36 per 100,000 person-years between 2003 and 2008. Computerized tomography identified the stone in 6% of adolescent stone formers (1 of 18) from 1984 to 1996 vs 76% (34 of 45) from 1997 to 2008. The incidence of spontaneous stone passage in adolescents did not increase significantly between these 2 periods (16 vs 18 per 100,000 person-years, p = 0.30).

CONCLUSIONS

The incidence of kidney stones increased dramatically among adolescents in the general population during a 25-year period. The exact cause of this finding remains to be determined.