Prospective Multicenter Evaluation of Pain Before and After Removal of Nonobstructing Renal Calculi: A CoRE Initiative.

PURPOSE: Flank pain associated with stone disease is typically caused by a stone that obstructs urine flow. However, it is plausible that nonobstructing kidney stones may still cause pain. We performed a multicenter, observational trial to evaluate whether treatment of small nonobstructing calyceal stones improves pain and kidney stone-specific health-related quality of life. MATERIALS AND METHODS: Patients aged 18 years or older with nonobstructing renal stone(s) up to 10 mm in longest diameter and moderate to severe pain were recruited. All participants completed 3 questionnaires: the Brief Pain Inventory (BPI), the Patient-Reported Outcomes Measurement Information System pain interference form 6a, and the Wisconsin Stone Quality of Life questionnaire. Thereafter, all participants underwent ureteroscopy for renal stone treatment. All 3 questionnaires were repeated at 2, 6 to 8, and at 12 weeks postprocedure. The primary outcomes were change in preoperative to 12-week postoperative mean BPI score and worst BPI pain score. RESULTS: A total of 43 patients with nonobstructing kidney stones and associated flank pain were recruited. All stones were removed. Preoperatively, BPI scores for mean pain and worst pain were 5.5 and 7.2, respectively which decreased to 1.8 and 2.8 respectively at 12 weeks postoperatively. Wisconsin Stone Quality of Life questionnaire mean score increased from 70.4 to 115.3 at 12 weeks postoperatively. A total of 86% and 69% of patients had at least a 20% and 50% reduction in their mean pain scores, respectively. CONCLUSIONS: This study determined that patients benefit significantly from the removal of calyceal nonobstructing kidney stones for at least 12 weeks with a reduction in pain and an increase in quality of life. Therefore, surgical removal of these stones in this patient population should be offered as a treatment option.

The Uniform grading tooL for flexIble ureterorenoscoPes (TULIP-tool): a Delphi consensus project on standardised evaluation of flexible ureterorenoscopes.

OBJECTIVE: To develop a standardised tool to evaluate flexible ureterorenoscopes (fURS). MATERIALS AND METHODS: A three-stage consensus building approach based on the modified Delphi technique was performed under guidance of a steering group. First, scope- and user-related parameters used to evaluate fURS were identified through a systematic scoping review. Then, the main categories and subcategories were defined, and the expert panel was selected. Finally, a two-step modified Delphi consensus project was conducted to firstly obtain consensus on the relevance and exact definition of each (sub)category necessary to evaluate fURS, and secondly on the evaluation method (setting, used tools and unit of outcome) of those (sub)categories. Consensus was reached at a predefined threshold of 80% high agreement. RESULTS: The panel consisted of 30 experts in the field of endourology. The first step of the modified Delphi consensus project consisted of two questionnaires with a response rate of 97% (n = 29) for both. Consensus was reached for the relevance and definition of six main categories and 12 subcategories. The second step consisted of three questionnaires (response rate of 90%, 97% and 100%, respectively). Consensus was reached on the method of measurement for all (sub)categories. CONCLUSION: This modified Delphi consensus project reached consensus on a standardised grading tool for the evaluation of fURS - The Uniform grading tooL for flexIble ureterorenoscoPes (TULIP) tool. This is a first step in creating uniformity in this field of research to facilitate future comparison of outcomes of the functionality and handling of fURS.

Estimating the health-related quality of life of kidney stone patients: initial results from the Wisconsin Stone Quality of Life Machine-Learning Algorithm (WISQOL-MLA).

OBJECTIVE: To build the Wisconsin Stone Quality of Life Machine-Learning Algorithm (WISQOL-MLA) to predict urolithiasis patients' health-related quality of life (HRQoL) based on demographic, symptomatic and clinical data collected for the validation of the Wisconsin Stone Quality-of-Life (WISQOL) questionnaire, an HRQoL measurement tool designed specifically for patients with kidney stones. MATERIAL AND METHODS: We used data from 3206 stone patients from 16 centres. We used gradient-boosting and deep-learning models to predict HRQoL scores. We also stratified HRQoL scores by quintile. The dataset was split using a standard 70%/10%/20% training/validation/testing ratio. Regression performance was evaluated using Pearson's correlation. Classification was evaluated with an area under the receiver-operating characteristic curve (AUROC). RESULTS: Gradient boosting obtained a test correlation of 0.62. Deep learning obtained a correlation of 0.59. Multivariate regression achieved a correlation of 0.44. Quintile stratification of all patients in the WISQOL dataset obtained an average test AUROC of 0.70 for the five classes. The model performed best in identifying the lowest (0.79) and highest quintiles (0.83) of HRQoL. Feature importance analysis showed that the model weighs in clinically relevant factors to estimate HRQoL, such as symptomatic status, body mass index and age. CONCLUSIONS: Harnessing the power of the WISQOL questionnaire, our initial results indicate that the WISQOL-MLA can adequately predict a stone patient's HRQoL from readily available clinical information. The algorithm adequately relies on relevant clinical factors to make its HRQoL predictions. Future improvements to the model are needed for direct clinical applications.

Radiation Dose Reduction of Unenhanced CT Limited to the Kidneys for Follow-Up of Patients With Known Nephrolithiasis Without Symptoms.

OBJECTIVE. The purpose of this study is to identify the landmarks and associated radiation dose reduction for limited CT of the kidneys of patients requiring follow-up for known nephrolithiasis. MATERIALS AND METHODS. This retrospective study included all adult patients who underwent CT examination type "CT abdomen + pelvis renal stone" at our institution during 2017. Several exclusion criteria were identified, including scoliosis and congenital renal abnormalities. A total of 299 patients met the inclusion and exclusion criteria. The radiation dose and z-axis length associated with the original CT scan were recorded. The upper and lower limits of both kidneys in relation to the vertebral body endplates were recorded, to determine the z-axis length for a CT scan limited to the kidneys. A commercially available radiation dose analytics software package was used to provide estimates of whole-body-and individual organ-equivalent doses for the original CT scan and the limited range CT scan. RESULTS. The superior endplate of T11 and the inferior endplate of L5 are landmarks that will include both kidneys on almost all scans. A limited z-axis range leads to a mean scan length reduction of 50%. The whole-body mean effective dose is reduced by 41.5%, and the doses to the breast and the gonadal and bladder organs are reduced by 71.7%, 73.8%, and 81.8%, respectively. CONCLUSION. For patients without symptoms who are undergoing CT surveillance to evaluate renal calculi growth, new stone formation, or both, a limited-range scan extending from the superior endplate of T11 to the inferior endplate of L5 results in a significant reduction in radiation dose.

Diagnostic Performance and Interreader Agreement of a Standardized MR Imaging Approach in the Prediction of Small Renal Mass Histology.

Purpose To assess the diagnostic performance and interreader agreement of a standardized diagnostic algorithm in determining the histologic type of small (≤4 cm) renal masses (SRMs) with multiparametric magnetic resonance (MR) imaging. Materials and Methods This single-center retrospective HIPAA-compliant institutional review board-approved study included 103 patients with 109 SRMs resected between December 2011 and July 2015. The requirement for informed consent was waived. Presurgical renal MR images were reviewed by seven radiologists with diverse experience. Eleven MR imaging features were assessed, and a standardized diagnostic algorithm was used to determine the most likely histologic diagnosis, which was compared with histopathology results after surgery. Interreader variability was tested with the Cohen κ statistic. Regression models using MR imaging features were used to predict the histopathologic diagnosis with 5% significance level. Results Clear cell renal cell carcinoma (RCC) and papillary RCC were diagnosed, with sensitivities of 85% (47 of 55) and 80% (20 of 25), respectively, and specificities of 76% (41 of 54) and 94% (79 of 84), respectively. Interreader agreement was moderate to substantial (clear cell RCC, κ = 0.58; papillary RCC, κ = 0.73). Signal intensity (SI) of the lesion on T2-weighted MR images and degree of contrast enhancement (CE) during the corticomedullary phase were independent predictors of clear cell RCC (SI odds ratio [OR]: 3.19; 95% confidence interval [CI]: 1.4, 7.1; P = .003; CE OR, 4.45; 95% CI: 1.8, 10.8; P < .001) and papillary RCC (CE OR, 0.053; 95% CI: 0.02, 0.2; P < .001), and both had substantial interreader agreement (SI, κ = 0.69; CE, κ = 0.71). Poorer performance was observed for chromophobe histology, oncocytomas, and minimal fat angiomyolipomas, (sensitivity range, 14%-67%; specificity range, 97%-99%), with fair to moderate interreader agreement (κ range = 0.23-0.43). Segmental enhancement inversion was an independent predictor of oncocytomas (OR, 16.21; 95% CI: 1.0, 275.4; P = .049), with moderate interreader agreement (κ = 0.49). Conclusion The proposed standardized MR imaging-based diagnostic algorithm had diagnostic accuracy of 81% (88 of 109) and 91% (99 of 109) in the diagnosis of clear cell RCC and papillary RCC, respectively, while achieving moderate to substantial interreader agreement among seven radiologists. © RSNA, 2018 Online supplemental material is available for this article.

Do Urinary Cystine Parameters Predict Clinical Stone Activity?

PURPOSE: An accurate urinary predictor of stone recurrence would be clinically advantageous for patients with cystinuria. A proprietary assay (Litholink, Chicago, Illinois) measures cystine capacity as a potentially more reliable estimate of stone forming propensity. The recommended capacity level to prevent stone formation, which is greater than 150 mg/l, has not been directly correlated with clinical stone activity. We investigated the relationship between urinary cystine parameters and clinical stone activity. MATERIALS AND METHODS: We prospectively followed 48 patients with cystinuria using 24-hour urine collections and serial imaging, and recorded stone activity. We compared cystine urinary parameters at times of stone activity with those obtained during periods of stone quiescence. We then performed correlation and ROC analysis to evaluate the performance of cystine parameters to predict stone activity. RESULTS: During a median followup of 70.6 months (range 2.2 to 274.6) 85 stone events occurred which could be linked to a recent urine collection. Cystine capacity was significantly greater for quiescent urine than for stone event urine (mean ± SD 48 ± 107 vs -38 ± 163 mg/l, p <0.001). Cystine capacity significantly correlated inversely with stone activity (r = -0.29, p <0.001). Capacity also correlated highly negatively with supersaturation (r = -0.88, p <0.001) and concentration (r = -0.87, p <0.001). Using the suggested cutoff of greater than 150 mg/l had only 8.0% sensitivity to predict stone quiescence. Decreasing the cutoff to 90 mg/l or greater improved sensitivity to 25.2% while maintaining specificity at 90.9%. CONCLUSIONS: Our results suggest that the target for capacity should be lower than previously advised.

Axial Abdominal Imaging after Partial Nephrectomy for T1 Renal Cell Carcinoma Surveillance.

PURPOSE: The overall recurrence rate of T1 renal cell carcinoma is low. We evaluated abdominal imaging after partial nephrectomy based on current guidelines for T1 renal cell carcinoma surveillance. MATERIALS AND METHODS: We retrospectively reviewed the records of patients with T1 renal cell carcinoma who underwent partial nephrectomy between 2006 and 2012 followed by abdominal imaging at our institution. Primary and secondary outcomes were the incidence and timing, respectively, of imaging diagnosed abdominal recurrences. A literature review was performed to summarize prior reports of recurrence incidence and timing after partial nephrectomy for T1 disease. RESULTS: A total of 160 patients with stage T1a and 37 with T1b underwent partial nephrectomy. Seven patients had an abdominal recurrence, including 3 with local and distant recurrences, and 4 with a metachronous contralateral kidney recurrence. The incidence of abdominal recurrence detected by imaging was higher in the T1b than in the T1a group (10.8% vs 1.9%, p = 0.024). Although it was not significant, median time to recurrence was earlier in T1b vs T1a cases (13 vs 37 months, p = 0.480). In each group recurrences developed after 3 years of suggested guideline surveillance. In the literature combined with the current study the time to median recurrence for T1b vs T1a was 24 vs 29 months (p = 0.226). CONCLUSIONS: Recurrences detected by abdominal imaging developed earlier and more frequently in T1b than in T1a cases. Future recommendations for surveillance strategies after partial nephrectomy should distinguish T1a from T1b with less intense frequency of imaging for T1a. A longer period of surveillance should be considered since recurrences can develop beyond 3 years.

Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging to Identify Clear Cell Renal Cell Carcinoma in cT1a Renal Masses.

PURPOSE: The detection of small renal masses is increasing with the use of cross-sectional imaging, although many incidental lesions have negligible metastatic potential. Among malignant masses clear cell renal cell carcinoma is the most prevalent and aggressive subtype. A method to identify such histology would aid in risk stratification. Our goal was to evaluate a likelihood scale for multiparametric magnetic resonance imaging in the diagnosis of clear cell histology. MATERIALS AND METHODS: We retrospectively reviewed the records of patients with cT1a masses who underwent magnetic resonance imaging and partial or radical nephrectomy from December 2011 to July 2015. Seven radiologists with different levels of experience who were blinded to final pathology findings independently reviewed studies based on a predefined algorithm. They applied a clear cell likelihood score, including 1-definitely not, 2-probably not, 3-equivocal, 4-probably and 5-definitely. Binary classification was used to determine the accuracy of clear cell vs all other histologies. Interobserver agreement was calculated with the weighted κ statistic. RESULTS: A total of 110 patients with 121 masses were identified. Mean tumor size was 2.4 cm and 50% of the lesions were clear cell. Defining clear cell as scores of 4 or greater demonstrated 78% sensitivity and 80% specificity while scores of 3 or greater showed 95% sensitivity and 58% specificity. Interobserver agreement was moderate to good with a mean κ of 0.53. CONCLUSIONS: A clear cell likelihood score used with magnetic resonance imaging can reasonably identify clear cell histology in small renal masses and may decrease the number of diagnostic renal mass biopsies. Standardization of imaging protocols and reporting criteria is needed to improve interobserver reliability.

Irreversible electroporation of small renal masses: suboptimal oncologic efficacy in an early series.

PURPOSE: To report on the first short-term oncologic outcomes of percutaneous irreversible electroporation for small renal masses. METHODS: Patients with cT1a renal masses treated with irreversible electroporation from April 2013 through December 2016 were reviewed. Small, low complexity tumors were generally selected for irreversible electroporation using the NanoKnife® System (Angiodynamics, Latham, NY, USA). Surveillance imaging was performed post-operatively, and survival analysis was completed using the Kaplan-Meier method. RESULTS: A total of 42 tumors in 41 patients underwent irreversible electroporation. Mean tumor size was 2.0 cm with a median R.E.N.A.L nephrometry score of 5. Twenty-nine patients (71%) were discharged the same day of the procedure and no major (Clavien grade II or higher) intraoperative or post-operative complications occurred. Initial treatment success rate was 93%; our three failures (7%) underwent salvage radiofrequency ablation. With a mean follow-up of 22 months, 2-year local recurrence-free survival was 83% for patients with biopsy confirmed renal cell carcinoma, 87% with biopsy confirmed or a history of renal cell carcinoma, and 92% for the intent-to-treat cohort. CONCLUSIONS: Although with low morbidity, in comparison to extirpation and conventional thermal ablation technologies, irreversible electroporation has suboptimal short-term local disease control results in this series of small, low complexity tumors. Larger series and longer follow-up will determine the durability of this modality.

The economics of stone disease.

The rising prevalence of kidney stone disease is associated with significant costs to healthcare systems worldwide. This is in part due to direct procedural and medical management costs, as well as indirect costs to health systems, patients, and families. A number of manuscripts evaulating the economics of stone disease have been published since the 2008s International Consultation on Stone Disease. These highlight costs associated with stone disease, including acute management, surgical management, and medical management. This work hopes to highlight optimization in care by reducing inefficient treatments and maximizing cost-efficient preventative strategies.

Likelihood of Incomplete Kidney Tumor Ablation with Radio Frequency Energy: Degree of Enhancement Matters.

PURPOSE: Larger size and clear cell histopathology are associated with worse outcomes for malignant renal tumors treated with radio frequency ablation. We hypothesize that greater tumor enhancement may be a risk factor for radio frequency ablation failure due to increased vascularity. MATERIALS AND METHODS: A retrospective review of patients who underwent radio frequency ablation for renal tumors with contrast enhanced imaging available was performed. The change in Hounsfield units (HU) of the tumor from the noncontrast phase to the contrast enhanced arterial phase was calculated. Radio frequency ablation failure rates for biopsy confirmed malignant tumors were compared using the chi-squared test. Multivariate logistic analysis was performed to assess predictive variables for radio frequency ablation failure. Disease-free survival was calculated using Kaplan-Meier analysis. RESULTS: A total of 99 patients with biopsy confirmed malignant renal tumors and contrast enhanced imaging were identified. The incomplete ablation rate was significantly lower for tumors with enhancement less than 60 vs 60 HU or greater (0.0% vs 14.6%, p=0.005). On multivariate logistic regression analysis tumor enhancement 60 HU or greater (OR 1.14, p=0.008) remained a significant predictor of incomplete initial ablation. The 5-year disease-free survival for size less than 3 cm was 100% vs 69.2% for size 3 cm or greater (p <0.01), while 5-year disease-free survival for HU change less than 60 was 100% vs 92.4% for HU change 60 or greater (p=0.24). CONCLUSIONS: Biopsy confirmed malignant renal tumors, which exhibit a change in enhancement of 60 HU or greater, experience a higher rate of incomplete initial tumor ablation than tumors with enhancement less than 60 HU. Size 3 cm or greater portends worse 5-year disease-free survival after radio frequency ablation. The degree of enhancement should be considered when counseling patients before radio frequency ablation.

The Usefulness of Chest X-Rays for T1a Renal Cell Carcinoma Surveillance.

PURPOSE: The overall incidence of pulmonary metastasis of T1 renal cell carcinoma is low. We evaluated the usefulness of chest x-rays based on the current AUA (American Urological Association) guidelines and NCCN Guidelines® for T1a renal cell carcinoma surveillance. MATERIALS AND METHODS: Between 2006 and 2012, 258 patients with T1a renal cell carcinoma were treated with partial nephrectomy, radical nephrectomy or radio frequency ablation with surveillance followup at our institution. A retrospective chart review was performed to identify demographics, pathological findings and surveillance records. The primary outcome was the incidence of asymptomatic pulmonary recurrences diagnosed by chest x-ray in cases of T1a disease. Our secondary outcome was a comparison of diagnoses by treatment modality (partial nephrectomy, radical nephrectomy or radio frequency ablation). RESULTS: Pulmonary metastases developed in 3 of 258 patients (1.2%) but only 1 (0.4%) was diagnosed by standard chest x-ray surveillance. Median followup in the entire cohort was 36 months (range 6 to 152) and 193 of 258 patients (75%) had greater than 24 months of followup. A mean of 3.3 surveillance chest x-rays were completed per patient. When assessed by treatment type, there was no significant difference in the recurrence rate for partial nephrectomy (0 of 191 cases), radical nephrectomy (0 of 22) or radio frequency ablation (1 of 45 or 2.2%) (p = 0.09). CONCLUSIONS: Chest x-rays are a low yield diagnostic tool for detecting pulmonary metastasis in patients treated for T1a renal cel carcinoma. Treatment mode does not appear to influence the need for chest x-ray surveillance.

Ablative Therapies for the Treatment of Small Renal Masses: a Review of Different Modalities and Outcomes.

The widespread utilization of abdominal imaging has led to an increase in incidentally detected small renal masses. Although partial nephrectomy is still considered the gold standard treatment for these masses, there are risks associated with surgical excision, potentially limiting treatment for older patients with multiple comorbidities. A variety of ablative techniques have developed over the past several decades, altering the management of small renal masses. It is likely that improvements in technology will only broaden the applications of ablative therapy. This article provides an update on the various ablative techniques and outcomes.

The Impact of Bilateral Stone Disease on Patients' Disease Progression and Health-Related Quality of Life.

Purpose: Patients with recurring kidney stone events can expect significant morbidity and functional impairment. Few studies have evaluated the effect of bilateral kidney stones on disease progression and quality of life. We wanted to determine the association of bilateral stone disease on age of onset, and the impact on number of stone events and individual kidney stone disease-specific health-related quality of life (HRQOL) by analyzing the validated and prospectively collected Wisconsin Stone Quality of Life (WISQOL) database. Materials and Methods: We studied 2906 stone patients from 16 centers in North America after having completed the WISQOL questionnaire from 2014 to 2019. Kidney stone formers were assessed if kidney stones were bilateral or unilateral on imaging. Analysis with a chi-square test compared categorical variables. Bilateral kidney stone disease and its impact on HRQOL were evaluated through a multivariable linear regression model. Results: Of 2906 kidney stone formers, 1340 had unilateral kidney stones and 1566 had bilateral kidney stones. We observed more frequently that patients with bilateral stones had an increased number of depression/anxiety symptoms, renal tubular acidosis, and rheumatoid arthritis (all p < 0.05). Patients with bilateral stones had a younger mean (standard deviation [SD]) age of kidney stone disease onset (37.2 ± 15.8 vs 46.4 ± 15.9 years of age, p < 0.001). Bilateral kidney stone formers had a higher mean (SD) number of stone events (11.3 ± 21.8) than unilateral kidney stone formers (3.0 ± 5.1) (p < 0.001). Within our multivariable analysis, we found that HRQOL was negatively affected by the presence of bilateral stones for kidney stone patients (ß = -11.2 [confidence interval: -19.5 to -3.0] points, p < 0.05). Conclusions: Bilateral kidney stone formers had a younger age of kidney stone disease onset and a higher number of stone events compared with unilateral kidney stone disease formers. The presence of bilateral kidney stone disease negatively impacted HRQOL.

Over-the-Counter Alkali Agents to Raise Urine pH and Citrate Excretion: A Prospective Crossover Study in Healthy Adults.

OBJECTIVE: To assess the effect of 2 over-the-counter alkalizing agents on 24 hour urinary parameters. MATERIALS AND METHODS: Ten healthy volunteers without a history of kidney stones were recruited to complete a baseline 24 hour urinalysis with a 4 day diet inventory. Participants then maintained the same diet on either LithoLyte (20 mEq 2 times per day) or KSPtabs (1 tablet 2 times per day) and submitted another 24 hour urinalysis. The process was repeated with the other supplement. Urinary alkali parameters were compared to baseline, and side effects were elicited with a questionnaire. RESULTS: LithoLyte intake resulted in a non-significant increase in citrate (597-758 mg/day, P =.058, an increase in urine pH (6.46-6.66, P =.028), and a decrease in urine ammonium (41-36 mmol/day, P =.005) compared to baseline. KSPtabs resulted in an increase in citrate (597-797 mg/day, P =.037) and urine pH (6.46-6.86, P =.037), with a non-significant decrease in ammonium (41-34 mmol/day, P =.059). No significant differences were seen comparing urinary analytes between LithoLyte and KSPtabs. With Litholyte, no side effects, mild, moderate, and severe side effects were seen in 50%, 40%, 10%, and 0%, respectively. With KSPtabs, rates were 60%, 20%, 10%, and 10%, respectively. CONCLUSION: In healthy participants without a history of kidney stones, LithoLyte and KSPtabs are effective over-the-counter alkali supplements, with a similar side effect profile to prescription potassium citrate.

The Duration of Stone Disease and the Impact of a Stone Event on Patients' Quality of Life.

Introduction: With a 5-year stone recurrence rate of 30% to 50%, kidney stone formers are subject to significant morbidity that negatively impacts their health-related quality of life (HRQOL). We sought to determine the impact of age at kidney stone onset, duration of stone disease, and kidney stone event (surgery or stone passage) on HRQOL of individual patients by querying the validated and prospectively collected Wisconsin Stone Quality of Life (WISQOL) database. Patients and Methods: Cross-sectional data were obtained from a total of 2438 kidney stone formers from 14 institutions in North America who completed the WISQOL questionnaire during the period from 2014 to 2019. The 28-question survey has a 1- to 5-point scale for each item (total score range 0-140). Multivariable linear regression models assessed the impact of age at kidney stone onset, duration of stone disease, and time since most recent surgery or stone passage on HRQOL. Results: Of 2438 patients, older age at kidney stone onset and longer duration of disease were both independent predictors of better WISQOL scores (ß = 0.33 points/year; confidence interval [CI] 0.17-0.49; p < 0.001; and ß = 0.50 points/year; CI 0.32-0.68; p < 0.001, respectively). Of 1376 patients who underwent surgery between 2010 and 2019, longer time since most recent surgery was an independent predictor of better WISQOL scores (ß = 2.28 points/year; CI: 1.47-3.10; p = <0.001). Of 1027 patients with spontaneous stone passage occurring between 2010 and 2019, longer time since most recent stone passage was an independent predictor of better WISQOL scores (ß = 1.59 points/year; CI: 0.59-2.59; p = <0.05). Conclusions: Our study demonstrates that older age at onset, longer duration of disease, and longer time since most recent surgery or stone passage were independent predictors of better HRQOL in kidney stone formers. Results of future studies that focus on optimizing stone-related modifiable risk factors to decrease the number of recurrent stone episodes and thus the need for recurrent surgeries will be essential.

Heterogeneity in stone culture protocols and endourologist practice patterns: a multi-institutional survey.

Kidney stone cultures can be beneficial in identifying bacteria not detected in urine, yet how stone cultures are performed among endourologists, under what conditions, and by what laboratory methods remain largely unknown. Stone cultures are not addressed by current clinical guidelines. A comprehensive REDCap electronic survey sought responses from directed (n = 20) and listserv elicited (n = 108) endourologists specializing in kidney stone disease. Questions included which clinical scenarios prompt a stone culture order, how results influence post-operative antibiotics, and what microbiology lab protocols exist at each institution with respect to processing and resulting stone cultures. Logistic regression statistical analysis determined what factors were associated with performing stone cultures. Of 128 unique responses, 11% identified as female and the mean years of practicing was 16 (range 1-46). A specific 'stone culture' order was available to only 50% (64/128) of those surveyed, while 32% (41/128) reported culturing stone by placing a urine culture order. The duration of antibiotics given for a positive stone culture varied, with 4-7 days (46%) and 8-14 days (21%) the most reported. More years in practice was associated with fewer stone cultures ordered, while higher annual volume of percutaneous nephrolithotomy was associated with ordering more stone cultures (p < 0.01). Endourologists have differing practice patterns with respect to ordering stone cultures and utilizing the results to guide post-operative antibiotics. With inconsistent microbiology lab stone culture protocols across multiple institutions, more uniform processing is needed for future studies to assess the clinical benefit of stone cultures and direct future guidelines.