Do Overweight and Obese Pediatric Stone Formers Have Differences in Metabolic Abnormalities Compared With Normal-weight Stone Formers?

Symptomatic recurrence rate of upper urinary tract calculi in children after endourological procedures

INTRODUCTION

The recurrence rate of paediatric urolithiasis was less reported, especially in Asians. Our aim was to verify the symptomatic recurrence rate of Chinese paediatric urolithiasis and to determine the predictive factors for stone recurrence.

MATERIALS AND METHODS

We performed a retrospective review of children who presented with first upper urinary tract calculi from June 2014 to September 2019. For the follow-up, we generated Kaplan-Meier plots with time to stone recurrence and Cox proportional hazard regression analyses were applied. The recurrence was defined as a new symptomatic stone on ultrasound and/or computerized tomography.

RESULTS

A total of 230 children with a median age of 5 yr (IQR 4-8) were included. Calcium oxalate was found in 72% of stones, and calcium apatite was found in 32% of stones. After a median follow-up of 39.5 months, 34 (14.8%) children had stone recurrence. Median time to stone recurrence was 31 months. Among them, 31 (91.2%) required surgical intervention. Older children (P < 0.01), higher BMI (HBM) (P < 0.01) and higher stone burden (P < 0.01) were shown to be associated with stone recurrence in the univariate analysis. The multivariate Cox regression analysis showed that children with stone burden > 2 cm³ had a higher risk of recurrence (HR 4.84, 95%CI 2.28-10.3). Children with HBM had an increased recurrence rate compared to normal BMI children (HR 2.99, 95%CI 1.36-6.56).

CONCLUSIONS

The symptomatic recurrence rate of paediatric urolithiasis in Chinese is not as high as that reported in Caucasians. HBM and higher stone burden are associated with higher recurrence rates.

The current status of preventive measures for urinary calculi in children

Urological calculus is a common disease in urology. Urological calculi are generally more common in adults but have become more common in children in recent years. Most existing studies focus on the prevention of urinary calculi in adults; there are relatively few articles on calculi in children. Reported preventive measures are not comprehensive enough, while the latest research progress has not been updated. The pathogenesis and preventive measures associated with urinary calculi have been the focus of research, but many preventive measures still need further clarification. This article reviews the progress on preventive measures for urinary calculi in children.

Effect of age, BMI, and gender on urinary risk factors in pediatric idiopathic stone formers

INTRODUCTION

The incidence of pediatric urolithiasis has been increasing over the years; however, the etiology of this increase is not well understood. Age, body mass index, and gender have been examined as possible risk factors for stone disease, but with inconsistent and variable associations.

OBJECTIVE

We aim to investigate the urine chemistry factors, as assessed by 24-h urinary parameters, in pediatric stone formers at a large volume tertiary referral center in the highest areas in the United States, the Southeast, based on age, body mass index, and gender.

STUDY DESIGN

We retrospectively reviewed all pediatric stone formers who completed a 24-h study between 2005 and 2016. Patients were stratified by age (3-10 versus 11-18 years of age), overweight status (above versus below the 85th percentile for body mass index), and gender (male versus female) (Summary Figure). Statistical analysis included analysis of variance and logistic regression.

RESULTS

243 patients were included in our analysis. Patients in the first decade of life were found to have greater numbers of urinary risk factors than those in the second decade. Non-overweight patients were more likely to have hyperoxaluria and hyperuricosuria, while overweight patients were more likely to have hypocitraturia. Female patients were more likely to have higher hyperoxaluria, while male patients were more likely to have hypercalciuria.

DISCUSSION

In contrast to prior publications, obesity is not linked to increased risk of urolithiasis with non-overweight individuals having a greater number of risk factors than the overweight cohort. Despite stone disease being more prevalent in adolescents, the greatest number of risk factors were present in the first decade of life. Lastly, female children had more urinary risk factors than males. Further understanding of the underlying causes of stone disease in various pediatric populations is warranted.

CONCLUSION

While more urinary risk factors were identified in younger, non-overweight, and female patients, there remains no consensus on the urinary risk factors for pediatric urolithiasis. Further study is needed to elucidate the risk factors and pathophysiology of pediatric stone disease.

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.

Dietary risk factors for urinary stones in children

PURPOSE OF REVIEW

As the incidence of urinary stone disease in children is increasing, identifying dietary risk factors becomes vitally important, especially in the context of targeting interventions to reduce risk for stone formation. Indiscriminant dietary restrictions are not appropriate for paediatric patients.

RECENT FINDINGS

Although large, prospective studies are still needed to better quantify dietary risk factors for paediatric stone formers, a number of smaller studies provide data to identify common risk factors to help prevent stone formation, while minimizing inappropriate dietary restrictions.

SUMMARY

Interpretation of 24-h urine samples to identify individualized dietary risk factors is crucial for implementing a strategy for prevention of further urinary stone formation in children. Clinicians should avoid generalized dietary restrictions in stone-forming children uninformed by laboratory data.

Risk factors for recurrent urolithiasis in children

PURPOSE

To identify risk factors associated with recurrent kidney stones in a paediatric cohort in a Belgian tertiary centre.

STUDY DESIGN AND METHODS

Medical records of children with the first episode of urolithiasis between 1998 and 2016, followed at Ghent University Hospital initially and at least one-year follow-up were retrospectively reviewed. Patient characteristics, past medical history, presenting symptoms, the results of laboratory investigations and the applied management strategy were analysed. The significant variables from the univariate analysis were integrated into a backward conditional multivariate model.

RESULTS

Ninety-seven children were included in the analysis, of which 33 (34%) presented with at least one episode of stone recurrence. In the univariate analysis, body mass index (BMI) > 85th percentile and asymptomatic stones at initial presentation were associated with 1.8 and 0.1 times lower risk of recurrent stones, respectively (p = 0.020, 95% confidence interval (CI):0.368-8.749 and p = 0.017, 95% CI:0.014-0.921). In contrast, immobilization resulted in a 10-times higher risk (p = 0.002, 95% CI:1.968-50.005) and the need for technical intervention was associated with a 3.2- times higher risk (p = 0.017, 95% CI:1.297-8.084) of developing recurrent stones. On multivariate analysis only BMI >85th percentile was associated with a 15 times lower risk of stone recurrence (p = 0.030, 95% CI:0.006-0.739).

DISCUSSION

A possible explanation of reduced risk in patients with a BMI > 85th percentile may lie in a different metabolic profile. Immobilization as a risk factor can be explained by calcium metabolism, which is influenced by immobilization due to fractures, paralysis or motor disability because it causes resorption of the skeleton resulting in elevated blood calcium levels. This study showed that patients who presented without symptoms when the stones first occurred were less likely to have recurring kidney stones compared with patients with symptoms at initial presentation. When technical intervention was needed, we believe this is partly due to a larger stone burden, however we could not find an evidence-based explanation. The institutional protocol, which allowed to create a database with a limited number of patients, was lost to follow-up. Despite the retrospective setting some data were missing. There might also be a bias because the patients were followed-up at a tertiary centre. Possibly, our conclusions cannot be generalized toward the entire paediatric population.

CONCLUSION

Of all the factors investigated in our cohort, BMI >85 th percentile and asymptomatic stones are associated with a lower risk of stone recurrence. Conversely, immobilized patients and those who require technical intervention at initial presentation may benefit from an intense follow-up after the first episode of urolithiasis.

Pediatric calculi: cause, prevention and medical management

PURPOSE OF REVIEW

The incidence of pediatric nephrolithiasis is on the rise, with a significant related morbidity and a concomitant relevant increase in healthcare costs. The purpose of this review is to portray the current epidemiology and cause of renal stones in children, to provide a framework for appropriate clinical evaluation on an individual basis, and a guidance regarding treatment and prevention for the significant risk of lifelong recurrence and deriving complications.

RECENT FINDINGS

The early identification of modifiable risk factors and other abnormalities is essential, to prevent related morbidity, the onset of chronic kidney disease, and the associated increased risk of developing other diseases. The implementation of risk reduction strategies, including dietary modifications and targeted pharmacological therapies, will significantly influence stone recurrences and preserve renal function.

SUMMARY

Future research is desirable, with the aim to strengthen personalized conservative management of pediatric nephrolithiasis as first-line treatment.

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.

Pediatric Stone Disease

Once considered rare, pediatric nephrolithiasis has become a critical field of study in the last decade due to the rapid increase in incidence. Understanding the changing epidemiology and lifelong implications of pediatric stone disease is critically important to effectively manage the individual patient as well as identify risk factors for childhood onset that could be modified. Determining the role of diagnostic imaging in children is a unique challenge as limiting radiation and imaging stewardship should be priorities. Approaches to management have also changed, as technology continues to evolve and both medical and surgical options expand.

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.

24 Hour urine metabolic differences between solitary and multiple stone formers: Results of the Collaboration on Urolithiasis in Pediatrics (CUP) working group

INTRODUCTION

Specific factors associated with the risk of developing pediatric urinary stone disease remain unclear, especially those that may be associated with recurrent stone disease.

OBJECTIVE

We compared the results of 24-h urine collections in children with a solitary stone episode to those with multiple stone episodes to determine if there is a difference that may be associated with multiple stone formation in children.

STUDY DESIGN

A multi-institutional retrospective analysis was completed to assess 24-h urinary metabolic profiles in children with urolithiasis aged 2-18 years old. Differences in mean urine collections between the two groups were assessed using chi-square tests to test the associations among gender, stone type, and multiple stone status, as well as multivariate analyses using general linear models.

RESULTS

We analyzed 142 solitary stone patients and 136 multiple stone patients from four centers were included. Multiple stone patients were older than solitary stone patients (mean 13.4 ± 3.6 years vs. 12 ± 3.9 years, p = 0.002). Females were more likely to have multiple stones (58% vs. 39%, p = 0.002). BMI was not associated with multiple stones (p = 0.8467). Multiple stone formers had lower urine volumes, although this did not reach statistical significance when compared with solitary stone formation (20.4 mL/kg/day ± 11.5 vs. 22.9 ± 13.0, p = 0.0880). Higher values for super-saturation of calcium oxalate were associated with multiple stone disease in univariate (p = 0.0485) and multivariate analysis (p = 0.0469) (Figure). Centers located in the Southeast of the United States saw a higher proportion of children with multiple stones (Tennessee 62.7%, Virginia 44.4%, Oregon 31.6%, Michigan 27.3%, p < 0.0001).

DISCUSSION

In a large multi-institutional retrospective analysis we found that multiple stone disease was associated with higher super-saturations of calcium oxalate. Many urinary parameters changed with patient age, highlighting that the values should be interpreted with respect to patient age. The inability to comment on follow-up because of the nature of our dataset is a limitation of this study.

CONCLUSION

Multiple stone disease in children is associated with higher super-saturation calcium oxalate, while lower urinary volume may also be associated with multiple stones; however, further study is required. Early metabolic evaluation may help risk stratify children likely to form multiple stones.