Kidney Stone Recurrence among Children and Adolescents.

PURPOSE: Kidney stone disease has become increasingly common during childhood and adolescence. However, the rate of symptomatic kidney stone recurrence for pediatric patients is uncertain. We sought to determine the recurrence rate of symptomatic kidney stones in a cohort of children with incident symptomatic nephrolithiasis. MATERIALS AND METHODS: We performed a retrospective cohort study of patients 3 to 18 years old without anatomical abnormalities or genetic causes of nephrolithiasis who presented with a first symptomatic kidney stone between 2008 and 2014. We determined recurrence rates of symptomatic nephrolithiasis, defined as a new kidney stone on ultrasound and/or computerized tomogram associated with pain and/or vomiting. We also estimated associations between completing 24-hour urinalysis and symptomatic kidney stone recurrence using Kaplan-Meier curves and multivariable Cox regression models. RESULTS: A total of 285 children with a median age of 14.8 years (IQR 11.3-16.6) at nephrolithiasis diagnosis were followed for 492 person-years. A total of 86 symptomatic recurrent stones developed in 68 patients (24%) during the followup period. The probability of symptomatic stone recurrence was 50% at 3 years after the index kidney stone. Median time to stone recurrence was 3 years at the first recurrence and 5 years at the second. Adjusting for confounders including adherence to followup, completing a 24-hour urinalysis after a kidney stone episode was associated with a 60% decreased risk of recurrence (hazard ratio 0.40, 95% CI 0.18-0.91). CONCLUSIONS: The risk of kidney stone recurrence is high during childhood, with approximately 50% of children presenting with symptomatic recurrence within 3 years of the first stone. The role and usefulness of analyzing 24-hour urine chemistries in decreasing kidney stone recurrence should be explored in future prospective studies.

Patient and institutional characteristics associated with initial computerized tomography in children presenting to the emergency department with kidney stones.

PURPOSE: Professional associations recommend ultrasound as the initial imaging study in children with suspected nephrolithiasis but computerized tomography remains frequently used. We identified patient and institutional characteristics associated with computerized tomography as the first imaging study in children with nephrolithiasis diagnosed in the emergency department. MATERIALS AND METHODS: We performed a cross-sectional study of children 2 to 18 years old with nephrolithiasis who were referred to a freestanding pediatric hospital from 2003 to 2012. We identified the imaging modality first used to evaluate the child. Medical directors at the emergency department where children were first evaluated were sent a questionnaire to ascertain emergency department characteristics. Multivariate hierarchical logistic regression models were used to determine patient and institutional characteristics associated with initial computerized tomography. RESULTS: Of 536 eligible children 323 (60.2%) were evaluated at emergency departments from which surveys were returned. Of the 323 children 238 (71%) underwent computerized tomography as initial imaging. Ultrasound was available at all emergency departments. Older patient age was associated with higher initial computerized tomography use (OR 1.09, 95% CI 1.04-1.16). A more recent year of diagnosis (OR 0.80, 95% CI 0.72-0.88) and a clinical care pathway that used ultrasound as initial imaging (OR 0.29, 95% CI 0.01-0.38) were associated with lower initial computerized tomography use. CONCLUSIONS: A clinical care pathway in the emergency department was the only institutional characteristic associated with lower computerized tomography use. Future studies are needed to determine whether care pathways using ultrasound for initial imaging in children with suspected nephrolithiasis would decrease inappropriate computerized tomography and improve adherence to national guidelines.

Morbidity and efficacy of ureteroscopic stone treatment in patients with neurogenic bladder.

PURPOSE: There is a lack of information on the safety and efficacy of ureteroscopy in the neurogenic bladder population. We hypothesized that ureteroscopy in patients with neurogenic bladder would be associated with an increased risk of complications and a lower stone clearance rate than in patients without neurological impairment. MATERIALS AND METHODS: We reviewed a local registry of patients with ICD-9 codes for urolithiasis between 2004 and 2012. The study cohort was assembled from all eligible patients with neurogenic bladder and a randomly selected control group that had undergone ureteroscopy. Statistical analysis of demographic variables and surgical outcomes was performed. Complications were classified according to the Clavien system. Clearance was defined by computerized tomography, renal/bladder ultrasound or direct ureterorenoscopy. RESULTS: Ureteroscopy was performed a total of 173 times in 127 controls and a total of 45 times in 20 patients with neurogenic bladder. There was no difference between presenting episodes by gender (p = 1.0), race (p = 0.654) or body mass index (p = 0.519). Bacteriuria was associated with the stone episode in 16.4% of controls and 67% of neurogenic bladder cases (p <0.001). Median operative time was significantly longer in those with neurogenic bladder (80.5 minutes, IQR 50-110.5 vs 52, IQR 33-78, p = 0.0003). The proportion of complications was significantly different (p = 0.013). Stones cleared in 86.6% of controls compared to 63% of neurogenic bladder cases (p = 0.004). CONCLUSIONS: Patients with neurogenic bladder have increased morbidity after ureteroscopy for upper tract calculi compared to neurologically unaffected controls. Infection has a role in this morbidity. The clearance rate is lower but the stone burden is more significant in those with neurogenic bladder.