Using structured problem solving to promote fluid consumption in the prevention of urinary stones with hydration (PUSH) trial.

BACKGROUND: Structured Problem Solving (SPS) is a patient-centered approach to promoting behavior change that relies on productive collaboration between coaches and participants and reinforces participant autonomy. We aimed to describe the design, implementation, and assessment of SPS in the multicenter Prevention of Urinary Stones with Hydration (PUSH) randomized trial. METHODS: In the PUSH trial, individuals with a history of urinary stone disease and low urine output were randomized to control versus a multicomponent intervention including SPS that was designed to promote fluid consumption and thereby prevent recurrent stones. We provide details specifically about training and fidelity assessment of the SPS coaches. We report on implementation experiences related to SPS during the initial conduct of the trial. RESULTS: With training and fidelity assessment, coaches in the PUSH trial applied SPS to help participants overcome barriers to fluid consumption. In some cases, coaches faced implementation barriers such as variable participant engagement that required tailoring their work with specific participants. The coaches also faced challenges including balancing rapport with problem solving, and role clarity for the coaches. CONCLUSIONS: We adapted SPS to the setting of kidney stone prevention and overcame challenges in implementation, such as variable patient engagement. Tools from the PUSH trial may be useful to apply to other health behavior change settings in nephrology and other areas of clinical care. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT03244189.

Ureteral Stent Placement Prior to Definitive Stone Treatment Is Associated With Higher Postoperative Emergency Department Visits and Opioid Prescriptions for Youth Having Ureteroscopy or Shock Wave Lithotripsy.

PURPOSE: Little is known about the impact of ureteral stents on youth having stone surgery. We evaluated the association of ureteral stent placement before or concurrent with ureteroscopy and shock wave lithotripsy with emergency department visits and opioid prescriptions among pediatric patients. MATERIALS AND METHODS: We conducted a retrospective cohort study of individuals aged 0-24 years who underwent ureteroscopy or shock wave lithotripsy from 2009-2021 at 6 hospitals in PEDSnet, a research network that aggregates electronic health record data from children's health systems in the United States. The exposure, primary ureteral stent placement, was defined as a stent placed concurrent with or within 60 days before ureteroscopy or shock wave lithotripsy. Associations between primary stent placement and stone-related ED visits and opioid prescriptions within 120 days of the index procedure were evaluated with mixed-effects Poisson regression. RESULTS: Two-thousand ninety-three patients (60% female; median age 15 years, IQR 11-17) had 2,477 surgical episodes; 2,144 were ureteroscopy and 333 were shock wave lithotripsy. Primary stents were placed in 1,698 (79%) ureteroscopy episodes and 33 (10%) shock wave lithotripsy episodes. Ureteral stents were associated with a 33% higher rate of emergency department visits (IRR 1.33; 95% CI 1.02-1.73) and a 30% higher rate of opioid prescriptions (IRR 1.30; 95% CI 1.10-1.53). The magnitudes of both associations were greater for shock wave lithotripsy. Results were similar for age <18 and were lost when restricted to concurrent stent placement. CONCLUSIONS: Primary ureteral stent placement was associated with more frequent emergency department visits and opioid prescriptions, driven by pre-stenting. These results support elucidating situations where stents are not necessary for youth with nephrolithiasis.

Deep Learning of Videourodynamics to Classify Bladder Dysfunction Severity in Patients With Spina Bifida.

PURPOSE: Urologists rely heavily on videourodynamics to identify patients with neurogenic bladders who are at risk of upper tract injury, but their interpretation has high interobserver variability. Our objective was to develop deep learning models of videourodynamics studies to categorize severity of bladder dysfunction. MATERIALS AND METHODS: We performed a cross-sectional study of patients aged 2 months to 28 years with spina bifida who underwent videourodynamics at a single institution between 2019 and 2021. The outcome was degree of bladder dysfunction, defined as none/mild, moderate, and severe, defined by a panel of 5 expert reviewers. Reviewers considered factors that increase the risk of upper tract injury, such as poor compliance, elevated detrusor leak point pressure, and detrusor sphincter dyssynergia, in determining bladder dysfunction severity. We built 4 models to predict severity of bladder dysfunction: (1) a random forest clinical model using prospectively collected clinical data from videourodynamics studies, (2) a deep learning convolutional neural network of raw data from the volume-pressure recordings, (3) a deep learning imaging model of fluoroscopic images, (4) an ensemble model averaging the risk probabilities of the volume-pressure and fluoroscopic models. RESULTS: Among 306 videourodynamics studies, the accuracy and weighted kappa of the ensemble model classification of bladder dysfunction when at least 75% expected bladder capacity was reached were 70% (95% CI 66%,76%) and 0.54 (moderate agreement), respectively. The performance of the clinical model built from data extracted by pediatric urologists was the poorest with an accuracy of 61% (55%, 66%) and a weighted kappa of 0.37. CONCLUSIONS: Our models built from urodynamic pressure-volume tracings and fluoroscopic images were able to automatically classify bladder dysfunction with moderately high accuracy.

Risk Factors for Increased Stent-associated Symptoms Following Ureteroscopy for Urinary Stones: Results From STENTS.

PURPOSE: The STudy to Enhance uNderstanding of sTent-associated Symptoms sought to identify risk factors for pain and urinary symptoms, as well as how these symptoms interfere with daily activities after ureteroscopy for stone treatment. MATERIALS AND METHODS: This prospective observational cohort study enrolled patients aged ≥12 years undergoing ureteroscopy with ureteral stent for stone treatment at 4 clinical centers. Participants reported symptoms at baseline; on postoperative days 1, 3, 5; at stent removal; and day 30 post-stent removal. Outcomes of pain intensity, pain interference, urinary symptoms, and bother were captured with multiple instruments. Multivariable analyses using mixed-effects linear regression models were identified characteristics associated with increased stent-associated symptoms. RESULTS: A total of 424 participants were enrolled. Mean age was 49 years (SD 17); 47% were female. Participants experienced a marked increase in stent-associated symptoms on postoperative day 1. While pain intensity decreased ∼50% from postoperative day 1 to postoperative day 5, interference due to pain remained persistently elevated. In multivariable analysis, older age was associated with lower pain intensity (P = .004). Having chronic pain conditions (P < .001), prior severe stent pain (P = .021), and depressive symptoms at baseline (P < .001) were each associated with higher pain intensity. Neither sex, stone location, ureteral access sheath use, nor stent characteristics were drivers of stent-associated symptoms. CONCLUSIONS: In this multicenter cohort, interference persisted even as pain intensity decreased. Patient factors (eg, age, depression) rather than surgical factors were associated with symptom intensity. These findings provide a foundation for patient-centered care and highlight potential targets for efforts to mitigate the burden of stent-associated symptoms.

The real world experience of pediatric primary hyperoxaluria patients in the PEDSnet clinical research network.

The rarity of primary hyperoxaluria (PH) challenges our understanding of the disease. The purpose of our study was to describe the course of clinical care in a United States cohort of PH pediatric patients, highlighting health service utilization. We performed a retrospective cohort study of PH patients < 18 years old in the PEDSnet clinical research network from 2009 to 2021. Outcomes queried included diagnostic imaging and testing related to known organ involvement of PH, surgical and medical interventions specific to PH-related renal disease, and select PH-related hospital service utilization. Outcomes were evaluated relative to cohort entrance date (CED), defined as date of first PH-related diagnostic code. Thirty-three patients were identified: 23 with PH type 1; 4 with PH type 2; 6 with PH type 3. Median age at CED was 5.0 years (IQR 1.4, 9.3 years) with the majority being non-Hispanic white (73%) males (70%). Median follow-up between CED and most recent encounter was 5.1 years (IQR 1.2, 6.8). Nephrology and Urology were the most common specialties involved in care, with low utilization of other sub-specialties (12%-36%). Most patients (82%) had diagnostic imaging used to evaluate kidney stones; 11 (33%) had studies of extra-renal involvement. Stone surgery was performed in 15 (46%) patients. Four patients (12%) required dialysis, begun in all prior to CED; four patients required renal or renal/liver transplant.    Conclusion: In this large cohort of U.S. PH children, patients required heavy health care utilization with room for improvement in involving multi-disciplinary specialists. What is Known: • Primary hyperoxaluria (PH) is rare with significant implications on patient health. Typical involvement includes the kidneys; however, extra-renal manifestations occur. • Most large population studies describe clinical manifestations and involve registries. What is New: • We report the clinical journey, particularly related to diagnostic studies, interventions, multispecialty involvement, and hospital utilization, of a large cohort of PH pediatric patients in the PEDSnet clinical research network. • There are missed opportunities, particularly in that of specialty care, that could help in the diagnosis, treatment, and even prevention of known clinical manifestations.

Quality of life impact and recovery after ureteroscopy and stent insertion: insights from daily surveys in STENTS.

BACKGROUND: Our objective was to describe day-to-day evolution and variations in patient-reported stent-associated symptoms (SAS) in the STudy to Enhance uNderstanding of sTent-associated Symptoms (STENTS), a prospective multicenter observational cohort study, using multiple instruments with conceptual overlap in various domains. METHODS: In a nested cohort of the STENTS study, the initial 40 participants having unilateral ureteroscopy (URS) and stent placement underwent daily assessment of self-reported measures using the Brief Pain Inventory short form, Patient-Reported Outcome Measurement Information System measures for pain severity and pain interference, the Urinary Score of the Ureteral Stent Symptom Questionnaire, and Symptoms of Lower Urinary Tract Dysfunction Research Network Symptom Index. Pain intensity, pain interference, urinary symptoms, and bother were obtained preoperatively, daily until stent removal, and at postoperative day (POD) 30. RESULTS: The median age was 44 years (IQR 29,58), and 53% were female. The size of the dominant stone was 7.5 mm (IQR 5,11), and 50% were located in the kidney. There was consistency among instruments assessing similar concepts. Pain intensity and urinary symptoms increased from baseline to POD 1 with apparent peaks in the first 2 days, remained elevated with stent in situ, and varied widely among individuals. Interference due to pain, and bother due to urinary symptoms, likewise demonstrated high individual variability. CONCLUSIONS: This first study investigating daily SAS allows for a more in-depth look at the lived experience after URS and the impact on quality of life. Different instruments measuring pain intensity, pain interference, and urinary symptoms produced consistent assessments of patients' experiences. The overall daily stability of pain and urinary symptoms after URS was also marked by high patient-level variation, suggesting an opportunity to identify characteristics associated with severe SAS after URS.

Kidney Outcomes and Hypertension in Survivors of Wilms Tumor: A Prospective Cohort Study.

OBJECTIVE: To assess the prevalence of therapy-related kidney outcomes in survivors of Wilms tumor (WT). STUDY DESIGN: This prospective cohort study included survivors of WT who were ≥5 years old and ≥1 year from completing therapy, excluding those with preexisting hypertension, prior dialysis, or kidney transplant. Participants completed 24-hour ambulatory blood pressure monitoring (ABPM). Abnormal blood pressure (BP) was defined as ≥90th percentile. Masked hypertension was defined as having normal office BP and abnormal ABPM findings. Urine was analyzed for kidney injury molecule-1, interleukin-18, epidermal growth factor, albumin, and creatinine. The estimated glomerular filtration rate (eGFR) was calculated using the bedside chronic kidney disease in children equation. Recent kidney ultrasound examinations and echocardiograms were reviewed for contralateral kidney size and left ventricular hypertrophy, respectively. Clinical follow-up data were collected for approximately 2 years after study enrollment. RESULTS: Thirty-two participants (median age, 13.6 years [IQR, 10.5-16.3 years]; 75% stage 3 or higher WT) were evaluated at a median of 8.7 years (IQR, 6.5-10.8 years) after therapy; 29 participants underwent unilateral radical nephrectomy, 2 bilateral partial nephrectomy, and 1 radical and contralateral partial nephrectomy. In this cohort, 72% received kidney radiotherapy and 75% received doxorubicin. Recent median eGFR was 95.6 mL/min/1.73 m2 (IQR, 84.6-114.0; 11 [34%] had an eGFR of <90 mL/min/1.73 m2). Abnormal ABPM results were found in 22 of 29 participants (76%), masked hypertension in 10 of 29 (34%), and microalbuminuria in 2 of 32 (6%). Of the 32 participants, 22 (69%) had abnormal epidermal growth factor; few had abnormal kidney injury molecule-1 or interleukin-18. Seven participants with previous unilateral nephrectomy lacked compensatory contralateral kidney hypertrophy. None had left ventricular hypertrophy. CONCLUSIONS: In survivors of WT, adverse kidney outcomes were common and should be closely monitored.

Optical Detection of Intracranial Pressure and Perfusion Changes in Neonates With Hydrocephalus.

OBJECTIVE: To demonstrate that a novel noninvasive index of intracranial pressure (ICP) derived from diffuse optics-based techniques is associated with intracranial hypertension. STUDY DESIGN: We compared noninvasive and invasive ICP measurements in infants with hydrocephalus. Infants born term and preterm were eligible for inclusion if clinically determined to require cerebrospinal fluid (CSF) diversion. Ventricular size was assessed preoperatively via ultrasound measurement of the fronto-occipital (FOR) and frontotemporal (FTHR) horn ratios. Invasive ICP was obtained at the time of surgical intervention with a manometer. Intracranial hypertension was defined as invasive ICP ≥15 mmHg. Diffuse optical measurements of cerebral perfusion, oxygen extraction, and noninvasive ICP were performed preoperatively, intraoperatively, and postoperatively. Optical and ultrasound measures were compared with invasive ICP measurements, and their change in values after CSF diversion were obtained. RESULTS: We included 39 infants, 23 with intracranial hypertension. No group difference in ventricular size was found by FOR (P = .93) or FTHR (P = .76). Infants with intracranial hypertension had significantly higher noninvasive ICP (P = .02) and oxygen extraction fraction (OEF) (P = .01) compared with infants without intracranial hypertension. Increased cerebral blood flow (P = .005) and improved OEF (P < .001) after CSF diversion were observed only in infants with intracranial hypertension. CONCLUSIONS: Noninvasive diffuse optical measures (including a noninvasive ICP index) were associated with intracranial hypertension. The findings suggest that impaired perfusion from intracranial hypertension was independent of ventricular size. Hemodynamic evidence of the benefits of CSF diversion was seen in infants with intracranial hypertension. Noninvasive optical techniques hold promise for aiding the assessment of CSF diversion timing.

Prevention of Urinary Stones With Hydration (PUSH): Design and Rationale of a Clinical Trial.

RATIONALE & OBJECTIVE: Although maintaining high fluid intake is an effective low-risk intervention for the secondary prevention of urinary stone disease, many patients with stones do not increase their fluid intake. STUDY DESIGN: We describe the rationale and design of the Prevention of Urinary Stones With Hydration (PUSH) Study, a randomized trial of a multicomponent behavioral intervention program to increase and maintain high fluid intake. Participants are randomly assigned (1:1 ratio) to the intervention or control arm. The target sample size is 1,642 participants. SETTING & PARTICIPANTS: Adults and adolescents 12 years and older with a symptomatic stone history and low urine volume are eligible. Exclusion criteria include infectious or monogenic causes of urinary stone disease and comorbid conditions precluding increased fluid intake. INTERVENTIONS: All participants receive usual care and a smart water bottle with smartphone application. Participants in the intervention arm receive a fluid intake prescription and an adaptive program of behavioral interventions, including financial incentives, structured problem solving, and other automated adherence interventions. Control arm participants receive guideline-based fluid instructions. OUTCOMES: The primary end point is recurrence of a symptomatic stone during 24 months of follow-up. Secondary end points include changes in radiographic stone burden, 24-hour urine output, and urinary symptoms. LIMITATIONS: Periodic 24-hour urine volumes may not fully reflect daily behavior. CONCLUSIONS: With its highly novel features, the PUSH Study will address an important health care problem. FUNDING: National Institute of Diabetes and Digestive and Kidney Diseases. TRIAL REGISTRATION: Registered at ClinicalTrials.gov with study number NCT03244189.

Perturbations of the Gut Microbiome and Metabolome in Children with Calcium Oxalate Kidney Stone Disease.

BACKGROUND: The relationship between the composition and function of gut microbial communities and early-onset calcium oxalate kidney stone disease is unknown. METHODS: We conducted a case-control study of 88 individuals aged 4-18 years, which included 44 individuals with kidney stones containing ≥50% calcium oxalate and 44 controls matched for age, sex, and race. Shotgun metagenomic sequencing and untargeted metabolomics were performed on stool samples. RESULTS: Participants who were kidney stone formers had a significantly less diverse gut microbiome compared with controls. Among bacterial taxa with a prevalence >0.1%, 31 taxa were less abundant among individuals with nephrolithiasis. These included seven taxa that produce butyrate and three taxa that degrade oxalate. The lower abundance of these bacteria was reflected in decreased abundance of the gene encoding butyryl-coA dehydrogenase (P=0.02). The relative abundance of these bacteria was correlated with the levels of 18 fecal metabolites, and levels of these metabolites differed in individuals with kidney stones compared with controls. The oxalate-degrading bacterial taxa identified as decreased in those who were kidney stone formers were components of a larger abundance correlation network that included Eggerthella lenta and several Lactobacillus species. The microbial (α) diversity was associated with age of stone onset, first decreasing and then increasing with age. For the individuals who were stone formers, we found the lowest α diversity among individuals who first formed stones at age 9-14 years, whereas controls displayed no age-related differences in diversity. CONCLUSIONS: Loss of gut bacteria, particularly loss of those that produce butyrate and degrade oxalate, associates with perturbations of the metabolome that may be upstream determinants of early-onset calcium oxalate kidney stone disease.

Re-Treatment after Ureteroscopy and Shock Wave Lithotripsy: A Population Based Comparative Effectiveness Study.

PURPOSE: Shock wave lithotripsy and ureteroscopy are the most commonly performed surgeries for kidney and ureteral stones, but the comparative effectiveness of these interventions at the population level is unclear. We compared re-treatment for shock wave lithotripsy and ureteroscopy. MATERIALS AND METHODS: A retrospective cohort study using all-payer claims data for all patients who underwent shock wave lithotripsy or ureteroscopy from 1997 to 2016 at 74 hospitals in South Carolina was performed. The primary outcome measure was subsequent shock wave lithotripsy or ureteroscopy within 6 months of initial surgery. Pseudorandomized trials of ureteroscopy vs shock wave lithotripsy were performed for each year, applying propensity scores to balance hospital and patient characteristics. Discrete time failure models were fit using propensity score weighted logistic regression. RESULTS: Overall 136,152 ureteroscopy and shock wave lithotripsy surgeries were performed in 95,227 unique patients with re-treatment representing 9% of all surgeries. A total of 74,251 index surgeries were shock wave lithotripsy (59.9%) and 49,743 were ureteroscopy (40.1%). Shock wave lithotripsy was associated with a 20% increased odds of re-treatment (OR 1.20; 95% CI 1.13-1.26). The probability of re-treatment was 7.5% for ureteroscopy and 10.4% for shock wave lithotripsy. Shock wave lithotripsy had the greatest risk of re-treatment at months 2 (OR 1.85; 95% CI 1.64-2.10) and 3 (OR 1.76; 95% CI 1.50-2.06). Patients with initial shock wave lithotripsy were more likely to have shock wave lithotripsy for re-treatment (84.6%) than those patients who had initial ureteroscopy were to have ureteroscopy (29.3%). CONCLUSIONS: Compared to ureteroscopy, shock wave lithotripsy was associated with increased odds of re-treatment. These results have implications for shared decision making and value based surgical treatment of nephrolithiasis.

Ecological Momentary Assessment of Factors Associated with Water Intake among Adolescents with Kidney Stone Disease.

PURPOSE: Maintaining high water intake decreases kidney stone recurrence but is difficult to do. Strategies to reduce stone recurrence among adolescents are lacking. We conducted an ecological momentary assessment study to identify factors associated with water intake in adolescents with nephrolithiasis. MATERIALS AND METHODS: The study population consisted of 15 female and 10 male patients 12 to 18 years old with at least 1 prior kidney stone. For 7 days participants used "smart" bottles to self-monitor water intake and received questionnaires randomly 4 times daily, which were completed in real time on mobile devices. The questionnaires ascertained awareness of water intake volume, awareness of water intake goals, perceived need to drink, access to water, alternative beverage consumption and attitudes toward bathrooms. Linear mixed effects models were fit to estimate the association between momentary responses and daily water intake. RESULTS: During 175 person-days 595 assessments (85%) were completed. Median daily water intake was 1,304 ml (IQR 848-1,832) and 20% of participants met their intake goal for 4 days or more. Unawareness of water intake volume was associated with drinking 690 ml less water per day (p = 0.04). A strong self-perceived need to drink more was associated with drinking 1,954 ml less water each day compared to no self-perceived need to drink more (p <0.01). Unawareness of intake goals was weakly associated with drinking 1,129 ml less water each day (p = 0.1). Access to water, alternative beverage consumption and bathroom aversion were not associated with water intake. CONCLUSIONS: Unawareness of water volume consumed and low responsiveness to perceived need to drink more were associated with low water intake. Interventions that help adolescents recognize when and identify how to increase water intake may be effective in decreasing stone recurrence.

Oral Antibiotic Exposure and Kidney Stone Disease.

Background Although intestinal and urinary microbiome perturbations are associated with nephrolithiasis, whether antibiotics are a risk factor for this condition remains unknown.Methods We determined the association between 12 classes of oral antibiotics and nephrolithiasis in a population-based, case-control study nested within 641 general practices providing electronic health record data for >13 million children and adults from 1994 to 2015 in the United Kingdom. We used incidence density sampling to match 25,981 patients with nephrolithiasis to 259,797 controls by age, sex, and practice at date of diagnosis (index date). Conditional logistic regression models were adjusted for the rate of health care encounters, comorbidities, urinary tract infections, and use of thiazide and loop diuretics, proton-pump inhibitors, and statins.Results Exposure to any of five different antibiotic classes 3-12 months before index date was associated with nephrolithiasis. The adjusted odds ratio (95% confidence interval) was 2.33 (2.19 to 2.48) for sulfas, 1.88 (1.75 to 2.01) for cephalosporins, 1.67 (1.54 to 1.81) for fluoroquinolones, 1.70 (1.55 to 1.88) for nitrofurantoin/methenamine, and 1.27 (1.18 to 1.36) for broad-spectrum penicillins. In exploratory analyses, the magnitude of associations was greatest for exposure at younger ages (P<0.001) and 3-6 months before index date (P<0.001), with all but broad-spectrum penicillins remaining statistically significant 3-5 years from exposure.Conclusions Oral antibiotics associated with increased odds of nephrolithiasis, with the greatest odds for recent exposure and exposure at younger age. These results have implications for disease pathogenesis and the rising incidence of nephrolithiasis, particularly among children.

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.

Assessment of the combination of temperature and relative humidity on kidney stone presentations.

Temperature and relative humidity have opposing effects on evaporative water loss, the likely mediator of the temperature-dependence of nephrolithiasis. However, prior studies considered only dry-bulb temperatures when estimating the temperature-dependence of nephrolithiasis. We used distributed lag non-linear models and repeated 10-fold cross-validation to determine the daily temperature metric and corresponding adjustment for relative humidity that most accurately predicted kidney stone presentations during hot and cold periods in South Carolina from 1997 to 2015. We examined three metrics for wet-bulb temperatures and heat index, both of which measure the combination of temperature and humidity, and for dry-bulb temperatures: (1) daytime mean temperature; (2) 24-h mean temperature; and (3) most extreme 24-h temperature. For models using dry-bulb temperatures, we considered four treatments of relative humidity. Among 188,531 patients who presented with kidney stones, 24-h wet bulb temperature best predicted kidney stone presentation during summer. Mean cross-validated residuals were generally lower in summer for wet-bulb temperatures and heat index than the corresponding dry-bulb temperature metric, regardless of type of adjustment for relative humidity. Those dry-bulb models that additionally adjusted for relative humidity had higher mean residuals than other temperature metrics. The relative risk of kidney stone presentations at the 99th percentile of each temperature metric compared to the respective median temperature in summer months differed by temperature metric and relative humidity adjustment, and ranged from an excess risk of 8-14%. All metrics performed similarly in winter. The combination of temperature and relative humidity determine the risk of kidney stone presentations, particularly during periods of high heat and humidity. These results suggest that metrics that measure moist heat stress should be used to estimate the temperature-dependence of kidney stone presentations, but that the particular metric is relatively unimportant.

Percutaneous nephrolithotomy in an 8-week-old infant.

We report successful percutaneous nephrolithotomy (PCNL) in an 8-week-old, 4.12 kg infant with a combined stone burden of > 2 cm in a solitary kidney. The patient was born with thoracolumbar myelomeningocele and had developed recurrent urinary tract infections. Her size precluded retrograde intrarenal surgery and shockwave lithotripsy would be unlikely to clear the stone burden. Stone analysis revealed hydroxyapatite and carbonate apatite stones, and metabolic work up revealed hypercalciuria for which chlorothiazide was started. To our knowledge, this is the youngest patient to undergo PCNL reported in the literature.

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.