Introduction: Existing studies link kidney stone treatment to reduced recurrent urinary tract infections (UTIs); however, these studies are limited by their retrospective design and/or lack of comparison group. The present study assesses a prospective observational cohort of patients with recurrent UTIs who selected observation or intervention for management of their non-obstructing kidney stones to assess for impact on UTI recurrence. Methods: From 2020−2025, patients with non-obstructing kidney stones and recurrent UTIs were prospectively enrolled at four centers. After shared decision-making, participants underwent observation or surgical intervention. The primary outcome was UTI recurrence at 12 months post-enrollment, defined as presence of urinary tract symptoms with positive urine culture. The study was powered to detect a 50% reduction in the rate of UTI recurrence between the groups at 12 months. Results: Among 94 patients recruited, followup data at 12 months was available for 21 observation and 46 intervention patients. There were more staghorn stones in the intervention group (15.2% vs. 0%), and the median stone size was larger (13.5 vs. 6 mm). At 12 months, 81% (n=17) in the observation group and 54% (n=25) in the intervention group had a symptomatic UTI recurrence (p=0.06, non-significant). The subgroup (n=17) of stone-free intervention patients had fewer UTI recurrences compared to the observation group (odds ratio 0.12, 95% confidence interval 0.02−0.66). Causation cannot be confirmed due to the observational nature of the study. Conclusions: For patients with recurrent UTIs and stones, surgical intervention is not associated with decreased risk of UTI recurrence at 12 months overall; however, patients who were stone-free after intervention had significantly fewer UTI recurrences on subgroup analysis.

INTRODUCTION:Ureteral stent placement after ureteroscopy is a major contributor to patient morbidity. We sought to evaluate postoperative complications and quality of life (QoL) metrics comparing individuals receiving ureteral stent placement vs. stent omission after ureteroscopy. METHODS:A multicenter, randomized controlled trial was performed among patients undergoing ureteroscopy and laser lithotripsy for non-obstructing renal stones with up to 1.5 cm in total stone diameter. Ureteral access sheath use and laser technique were at the discretion of the surgeon. At case end, if no ureteral injury was observed, patients were randomized to stent placement or stent omission. Primary outcome was the 30-day occurrence of emergency department visits, unanticipated provider visits, or hospitalization. Secondary outcomes included QoL measured by the Wisconsin Stone Quality of Life (WISQOL) and the Patient-Reported Outcomes Measurement Information System (PROMIS) pain interference surveys, opiate use, and abnormal imaging findings at followup. RESULTS:Of 103 patients enrolled with mean (standard deviation [SD]) stone diameter 9.6 mm (4.5), 74 were randomized to stent placement (n=36) or stent omission (n=38). Ureteral access sheaths were used in 83% and 61% of patients in the stented and unstented groups, respectively. There was no difference in rate of 30-day complications between stent and stent omission cohorts (8% vs. 11%, absolute risk difference -2%, 95% confidence interval [CI] -15%, 11%, p=0.75). Stent omission showed better adjusted pre- vs. post-surgery WISQOL scaled score (16.7, 95% CI 3.1, 30.4, p=0.02) and PROMIS 6a t-score (-8.5, 95% CI -15.3, -1.6, p=0.02). No differences between groups were observed in the cumulative opiate use, ability to return to work, symptomatic urinary tract infection, or abnormal imaging findings at followup. CONCLUSIONS:Compared to ureteral stent placement, stent omission after ureteroscopy for renal stones appears to be feasible and suggests improved short-term patient-reported outcomes in selected patients. This study was limited by small sample size, and future larger studies are needed.

Objective: To evaluate surgeon consensus on stone dust quality and the ability to predict stone-free status based on intraoperative endoscopic appearance during ureteroscopy (URS) with laser lithotripsy. Methods: Fifteen urologists (7 faculty, 8 trainees) reviewed 16 videos of ureteroscopic laser lithotripsy, blinded to clinical outcomes. Eight videos were from patients who were stone-free at 6-week postoperative computed tomography; eight had residual fragments. Reviewers rated stone dust quality on a 5-point Likert scale and predicted stone-free status. Inter-rater reliability was measured using the intraclass correlation coefficient (ICC). Accuracy of stone-free prediction was compared using a two-tailed t test. Results: Inter-rater agreement on dust quality was poor (ICC = 0.41), with slightly higher agreement among faculty (ICC = 0.49) compared to trainees (ICC = 0.38). Mean accuracy of stone-free prediction was 63% (SD: 9%), with no significant difference between faculty and trainees (67% vs 58%, P = .05). Sensitivity and specificity of predicting residual fragments were 55% and 72%, respectively. Confidence in predictions did not differ between groups. Notably, three of eight cases with residual fragments resulted in significant clinical events (ICU admission, reintervention), with mean time to event of 221 days. In these, surgeon prediction accuracy remained modest (63%, SD: 14%). Conclusion: Surgeon assessment of stone dust quality is inconsistent, and predictive accuracy for stone-free status based on endoscopic appearance is limited. These findings underscore the need for standardized definitions and objective intraoperative tools to optimize outcomes in laser stone surgery.

PURPOSE:The purpose of this Guideline is to provide a framework for the medical evaluation, treatment, and follow-up of patients with a history of kidney stones in order to reduce the likelihood of recurrent disease. The summary presented herein represents Part I of the two-part series dedicated to Medical Management of Kidney Stones. Please refer to Part II for additional information on this topic. MATERIALS AND METHODS:The systematic review utilized in the creation of this Guideline is based on research conducted by the Research Triangle Institute (RTI) International-University of North Carolina at Chapel Hill Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ) and funded by the Patient-Centered Outcomes Research Institute (PCORI). The EPC extracted and synthesized comparative effectiveness and harms outcomes for preventive treatment with diet or pharmacologic agents and surveillance imaging strategies in nonpregnant adults and children with a history of nephrolithiasis from 30 publications. RESULTS:A series of Guideline statements were developed that addresses the identification of individuals at high-risk of stone recurrence, the metabolic evaluation of high-risk and interested patients, treatment with dietary measures and pharmacologic therapy, and follow-up for assessment of therapeutic effects. The statements were developed based on the evidence base for this Guideline. CONCLUSIONS:Using the best available evidence and the expert opinions of the Panel, this Guideline offers recommendations for the initiation of dietary measures and drug therapy to allow for active treatment of motivated and high-risk patients with the goal of reducing the risk of stone recurrence.

PURPOSE:To assess variation in surveillance imaging practices in various clinical contexts among patients with urinary stone disease (USD) from a large cohort of U.S. Veterans. MATERIALS AND METHODS:We identified adults age ≥18 years within the Veterans Health Administration Corporate Data Warehouse with an index surgical procedure related to USD or an index emergency department (ED) visit with a primary diagnosis of USD between 2010 and 2018. We then explored three clinical periods for use of surveillance imaging: 30-180 days and 180-540 days post-surgery and 90-540 days post-ED visit. We estimated multilevel logistic regression models to identify factors associated with receipt of surveillance imaging. We calculated median odds ratios (MORs) to quantify the amount of variation in imaging procedures by facility. RESULTS:Among 35,248 patients who met the inclusion criteria, 10,095 underwent a surgical procedure, and 25,153 had an ED visit. Probabilities of obtaining postoperative imaging 30-180 days post-surgery by facility ranged from 8.4% to 58.5%; from 6.8% to 35.4% for 180-540 days post-surgery; and from 6.1% to 20.5% for 90-540 days post-ED. The greatest between-facility variation occurred 30-180 days post-surgery (MOR: 1.81 [95% confidence interval], 1.66-2.04). There was also wide variation in the type of post-surgical imaging. Combination imaging, X-ray, and ultrasound were the most common imaging modalities obtained in the 30-180 day period for percutaneous nephrolithotomy, shockwave lithotripsy, and ureteroscopy, respectively. CONCLUSIONS:Among patients with USD, the use of surveillance imaging after surgical procedure and in the post-ED visit setting remains low, with substantial variation across facilities.

BACKGROUND:Nephrolithiasis recurs after an initial episode within 5 years for 30-50% of stone formers without dietary and/or pharmacological therapy to prevent or reduce stone recurrence. Preventive interventions target increasing urine volume or altering urinary concentration of key risk factors: high calcium, oxalate or uric acid and low urinary citrate. Two strategies for achieving stone prevention involve an untailored generalized approach (empiric therapy) and an approach tailored to results from 24 h urine testing (selective therapy). METHODS:Adults with recurrent kidney stone disease were randomly assigned to empiric (Emp) or selective (Sel) therapy upon completing 24 h urine testing. Participants in the Emp group received standard guideline-based diet and medication therapy. Participants in the Sel group received therapy tailored to their 3 most severe urine abnormalities. Within-group differences in dietary and urinary variables were assessed via the Wilcoxon test and difference between groups in changes from baseline to 8 weeks via general linear modeling. RESULTS:The Emp group had a 33% reduction in dietary oxalic acid intake (p = 0.02), but no significant changes in intakes of water, sodium, animal-based protein, or servings of fruits and vegetables. There were also no significant changes in urine volume or urinary sodium excretion. Overall, Sel participants increased daily intake of water by 17% (p = 0.02), doubled their number of daily fruit/vegetable servings (p = 0.04), and reduced their oxalate (p = 0.04) and sodium (p = 0.05) intakes. Sel participants in the urinary citrate and calcium subgroups showed greater reductions in urinary calcium oxalate supersaturation (-38%) compared to the Emp group (-30%). CONCLUSIONS:The findings suggest that a more personalized approach with a limited number of dietary targets supports improvements that are less likely to occur with empiric therapy which reflects a "one size fits all" method. However, even with tailored therapy, the inter-individual variability in dietary intake and response to treatment must be considered as adherence to dietary recommendations is particularly challenging in a condition that is lifelong. This trial was registered at clinicaltrials. gov NCT05365477.

PURPOSE:To compare a strategy using testing to guide treatment, also known as selective therapy, with a strategy of initiating interventions without testing, termed empiric therapy, on urinary supersaturation of calcium oxalate and calcium phosphate. MATERIALS AND METHODS:In this single-center trial, adult individuals with recurrent idiopathic calcium stone disease were randomized to either an empiric or selective strategy. Participants received 24-hour urine testing at baseline, 4 weeks, and 8 weeks. Treatment in the empiric arm comprised dietary and fluid counseling and pharmacologic treatment with indapamide and potassium citrate irrespective of 24-hour urine results. For the selective arm, diet, and pharmacologic treatments, which included indapamide, potassium citrate, and/or allopurinol, were tailored based on urine testing at baseline and 4 weeks. The primary outcome was urinary supersaturation of calcium oxalate and calcium phosphate at 8 weeks. RESULTS:The analytic sample included 56 participants (mean [SD] age, 44.5 [13.2] years; 30 women [54%]), with 29 randomized to the empiric and 27 to the selective groups. At week 8, there were no significant differences comparing the empiric and selective arms with respect to mean [SD] urinary supersaturation of calcium oxalate (4.7 [2.9] vs 5.0 [2.9], respectively, P = .81) or calcium phosphate (1.3 [0.9] vs 1.4 [1.1], respectively, P = .58). Similarly, there were no significant differences at 8 weeks in urine volume and pH or in excretion of calcium, oxalate, citrate, uric acid, and sodium. CONCLUSIONS:In this short-term trial among individuals at high risk for stone recurrence, there was no statistically significant difference in the urinary stone risk comparing an empiric vs selective strategy for kidney stone prevention.

INTRODUCTION:The FlexStone device (EndoTheia, Nashville, TN) is an investigational, steerable stone basket. The device provides additional flexion separate from the ureteroscope without an assistant. We evaluated the safety and feasibility of this new novel device for stone retrieval. PATIENTS AND METHODS:In this first-in-human clinical trial, 10 patients underwent flexible ureteroscopy (URS) for renal calculi using the FlexStone device. The primary endpoint was the safe and successful basketing of renal stones with the device. Intraoperative and short-term postoperative adverse events were evaluated. Secondary endpoints included surgeon workload assessed by the National Aeronautics and Space Administration Task Load Index (NASA-TLX). OUTCOMES:The majority of patients had a solitary stone (60%) and stone was in the lower pole (90%) with a minority of patients also having stones in upper pole (20%) or interpolar region (10%). Median cumulative axial stone size was 11 mm (interquartile range [IQR]: 7.5-15.25 mm). The device was used to extract (60%) or reposition (40%) of stones. Surgeons used the FlexStone device to successfully basket target stones in 9 cases (90%). No intraoperative complications occurred. Postoperatively, one patient needed a second URS procedure for hydronephrosis, but no obstructing stone was seen. On the NASA-TLX scale from 1 (low) to 21 (high), the demand when using the device was low, with median mental demand-6 (IQR: 4-12), physical demand-9 (IQR: 6-12), temporal demand-6 (IQR: 4-6), and frustration-6 (IQR: 1-6). Surgeons rated the device with high overall performance (median 3, IQR: 3-8, perfect = 1). CONCLUSION:Our preliminary investigation demonstrates the safety of a new, unique steerable stone basket. The FlexStone device is a potentially valuable addition to the urologist's armamentarium, especially for complex caliceal anatomy and improving ergonomics when using URS.

Objective To evaluate the association between heat index and kidney stone recurrence in a national Veterans Affairs cohort of kidney stone formers. Methods This retrospective cohort study of patients with an index kidney stone event from 2010-2020 used Veterans Healthcare Administration data. Heat exposure was defined as number of days per year exceeding the 95th percentile heat index and was modeled both as a continuous and categorical (quartiles) variable. Cox proportional hazards models additionally adjusting for demographics, rurality, social deprivation, and high-risk status for kidney stone recurrence, were used to assess the association with subsequent stone recurrence. Results Among 136,340 patients, crude rates of recurrence ranged from 10.1% in the second quartile to 12.7% in the fourth quartile of heat exposure over the seven-year follow-up period. In adjusted analysis, patients in the highest quartile of heat exposure had a 5% greater risk compared with the lowest quartile (HR, 1.05; 95% CI, 1.01 to 1.10; P=0.028). Modeling heat exposure as continuous, each 10-day increase in annual extreme heat days was associated with a 3% higher risk (HR, 1.03, 95% CI, 1.01 to 1.05); P=0.003). Conclusion Higher heat index is associated with kidney stone recurrence risk in U.S. Veterans. These findings suggest clinicians should consider environmental heat index when counseling high-risk patients.

PURPOSE:Previous studies have shown that thiazide diuretics' ability to decrease symptomatic stone events depends on the extent to which they reduce urine calcium. However, it remains unknown whether the calcium change from thiazide diuretics depends on the baseline urine calcium level. MATERIALS AND METHODS:Among a cohort of Medicare beneficiaries with a 24-hour urine collection for kidney stone disease processed by Labcorp/Litholink between 2011 and 2018, we identified a subset aged > 18 years newly prescribed a thiazide diuretic who performed a second collection between 30 and 180 days after their initial prescription fill. We then fit multivariable linear regression models to estimate the association between dose of thiazide prescribed and change in urine calcium, stratifying by baseline urine calcium. We compared cumulative incidences of clinical stone events stratified by baseline urine calcium groups within a treated and untreated cohort. RESULTS:From a total of 634 participants, higher baseline urine calcium was associated with greater 24-hour mean absolute (in mg/d) and percentage urine calcium reductions (Ptrend < 0.001 for both). Higher thiazide dose was associated with greater absolute and percentage urine calcium reduction. No statistically significant differences were seen comparing the adjusted incidences of clinical stone events across baseline calcium groups after thiazide prescription. However, among individuals without thiazide exposure, the unadjusted and adjusted cumulative incidences were higher with greater baseline urine calcium (both Ptrend < 0.001). CONCLUSIONS:Greater urine calcium reductions after thiazide treatment are observed among those with higher baseline urine calcium, and higher thiazide dose led to a larger reduction. These data are relevant for individualizing thiazide dose for kidney stone prevention.

KEY POINTS:Pharmacy claims-based adherence (percentage of days covered) and urine-based adherence (change in urinary potassium excretion divided by dose) showed discordant associations with physiologic response and recurrence. Although change in urinary potassium excretion divided by dose was more strongly associated with changes in urinary citrate and pH, only percentage of days covered was significantly associated with recurrent stone events. BACKGROUND:Patient adherence limits the effectiveness of preventive pharmacologic therapy (PPT) for urinary stone disease, highlighting the need for accurate adherence monitoring. We assessed associations between potassium citrate adherence measures, changes in 24-hour urine parameters, and the risk of recurrent stone events. METHODS:In this retrospective cohort study, we identified adult patients enrolled in Medicare with urinary stone disease, a baseline 24-hour urine collection (2010-2019), hypocitraturia or low urine pH, a prescription for potassium citrate monotherapy, and a follow-up urine collection. We defined two adherence measures: ( 1 ) percentage of days covered (PDC) using pharmacy claims and ( 2 ) change in urinary potassium between baseline and follow-up divided by medication dose (change in urinary potassium excretion divided by dose [ΔK/dose]). We assessed the association of these measures with changes in urinary citrate and pH using analysis of covariance, and the association between adherence and recurrent stone events using Cox models. RESULTS:Among 793 patients meeting the study criteria, 504 (63.6%) patients were adherent on the basis of pharmacy claims (PDC ≥80%) and 389 (49.1%) patients on the basis of ΔK/dose ≥0.5. Compared with PDC ≥80%, ΔK/dose ≥0.5 had a stronger association with change in urinary citrate ( P < 0.001) and pH ( P < 0.001). Compared with PDC ≥80%, patients with PDC <80% had a higher risk of recurrent stone events (hazard ratio, 1.431; 95% confidence interval, 1.049 to 1.952), whereas ΔK/dose was not statistically significantly associated with recurrent stone events (hazard ratio, 1.032; 95% confidence interval, 0.740 to 1.439). CONCLUSIONS:There are clinically meaningful differences in potassium citrate adherence measures. ΔK/dose was more strongly associated with the change in urinary citrate and pH. However, only PDC was significantly associated with recurrent stone events.

PURPOSE:The purpose of this Guideline is to provide a framework for the treatment and follow-up of patients with a history of kidney stones in order to reduce the likelihood of recurrent disease. The summary presented herein represents Part II of the two-part series dedicated to Medical Management of Kidney Stones. Please refer to Part I for additional information on this topic. MATERIALS AND METHODS:The systematic review utilized in the creation of this Guideline is based on research conducted by the Research Triangle Institute (RTI) International-University of North Carolina at Chapel Hill Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ) and funded by the Patient-Centered Outcomes Research Institute (PCORI). The EPC extracted and synthesized comparative effectiveness and harms outcomes for preventive treatment with diet or pharmacologic agents and surveillance imaging strategies in nonpregnant adults and children with a history of nephrolithiasis from 30 publications. RESULTS:A series of Guideline statements were developed that addresses the identification of individuals at high-risk of stone recurrence, the metabolic evaluation of high-risk and interested patients, treatment with dietary measures and pharmacologic therapy, and follow-up for assessment of therapeutic effects. The statements were developed based on the evidence base for this Guideline. CONCLUSIONS:Using the best available evidence and the expert opinion of the Panel, this Guideline offers recommendations for the initiation of dietary measures and drug therapy are provided to allow for active treatment of motivated and high-risk patients with the goal of reducing the risk of stone recurrence.

OBJECTIVE:To define the risk of laboratory abnormalities associated with commonly prescribed medications in the context of urinary stone disease (USD). MATERIALS AND METHODS:We used the Veterans Health Administration Corporate Warehouse to identify adults ≥ 18 years with an index episode of USD. The development of laboratory abnormalities for those ever versus never on preventive pharmacological therapy was then compared using separate Cox proportional hazards regression models for each laboratory abnormality-drug class combination, adjusting for baseline patient characteristics and time-varying medication use over the study period. To provide a sense for absolute risk, we then used the models to estimate 2-year predicted probabilities of developing a laboratory abnormality for each. RESULTS:Thiazide use was associated with a risk of: hypokalemia (hazard ratio [HR], 2.85; 95% confidence interval [CI], 2.66-3.05), hyponatremia (HR 1.41, 95% CI: 1.24-1.60), and hypercalcemia (HR 2.04, 95% CI: 1.70-2.46). Potassium citrate was associated with a risk of hyperkalemia (HR 1.44, 95% CI: 1.23-1.69). Allopurinol was associated with a risk of cytopenia (HR 1.17, 95% CI: 1.02-1.33). No significant association was observed between thiazide use and hyperglycemia or allopurinol use and transaminitis. The greatest absolute risk was for hypokalemia with thiazide use: a 2-year predicted probability of 17.3%. CONCLUSION:Preventive pharmacological therapy for USD is associated with an increased risk of a variety of laboratory abnormalities, with the greatest absolute risk being hypokalemia with thiazides at over 1 in 6 patients. The study findings provide guidance for laboratory monitoring while on these therapies.