The impact of kidney stone disease on quality of life in high-risk stone formers

OBJECTIVE

To assess the impact of kidney stone disease (KSD) and its treatment on the health-related quality of life (HRQOL) of high-risk stone formers with hyperparathyroidism, renal tubular acidosis, malabsorptive disease, and medullary sponge kidney.

PATIENTS AND METHODS

The Wisconsin Stone Quality of Life questionnaire was used to evaluate HRQOL in 3301 patients with a history of KSD from 16 institutions in North America between 2014 and 2020. Baseline characteristics and medical history were collected from patients, while active KSD was confirmed through radiological imaging. The high-risk group was compared to the remaining patients (control group) using the Wilcoxon rank-sum test.

RESULTS

Of 1499 patients with active KSD included in the study, the high-risk group included 120 patients. The high-risk group had significantly lower HRQOL scores compared to the control group (P < 0.01). In the multivariable analyses, medullary sponge kidney disease and renal tubular acidosis were independent predictors of poorer HRQOL, while alkali therapy was an independent predictor of better HRQOL (all P < 0.01).

CONCLUSIONS

Among patients with active KSD, high-risk stone formers had impaired HRQOL with medullary sponge kidney disease and renal tubular acidosis being independent predictors of poorer HRQOL. Clinicians should seek to identify these patients earlier as they would benefit from prompt treatment and prevention.

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 (β = -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.

Caution! AI Bot Has Entered the Patient Chat: ChatGPT Has Limitations in Providing Accurate Urologic Healthcare Advice

OBJECTIVE

To conduct the first study examining the accuracy of ChatGPT, an artificial intelligence (AI) chatbot, derived patient counseling responses based on clinical care guidelines in urology using a validated questionnaire.

METHODS

We asked ChatGPT a set of 13 urological guideline-based questions three times. Answers were evaluated for appropriateness and using Brief DISCERN (BD), a validated healthcare information assessment questionnaire. Data analysis included descriptive statistics and Student's t test (SAS Studio).

RESULTS

60% (115/195) of ChatGPT responses were deemed appropriate. Variability existed between responses to the same prompt, with 25% of the 13 question sets having discordant appropriateness designations. The average BD score was 16.8 ± 3.59. Only 7 (54%) of 13 topics and 21 (54%) of 39 responses met the BD cut-off score of ≥16 to denote good-quality content. Appropriateness was associated with higher overall and Relevance domain scores (both P < .01). The lowest BD domain scores were for Source categories, since ChatGPT does not provide references by default. With prompting, 92.3% had ≥1 incorrect, misinterpreted, or nonfunctional citations.

CONCLUSION

While ChatGPT provides appropriate responses to urological questions more than half of the time, it misinterprets clinical care guidelines, dismisses important contextual information, conceals its sources, and provides inappropriate references. Chatbot models hold great promise, but users should be cautious when interpreting healthcare-related advice from existing AI models. Additional training and modifications are needed before these AI models will be ready for reliable use by patients and providers.

Clinical Considerations for Patients Experiencing Acute Kidney Injury Following Percutaneous Nephrolithotomy

Acute kidney injury (AKI) is a common postoperative outcome in urology patients undergoing surgery for nephrolithiasis. The objective of this study was to determine the prevalence of postoperative AKI and its degrees of severity, identify risk factors, and understand the resultant outcomes of AKI in patients with nephrolithiasis undergoing percutaneous nephrolithotomy (PCNL). A cohort of patients admitted between 2012 and 2019 to a single tertiary-care institution who had undergone PCNL was retrospectively analyzed. Among 417 (n = 326 patients) encounters, 24.9% (n = 104) had AKI. Approximately one-quarter of AKI patients (n = 18) progressed to Stage 2 or higher AKI. Hypertension, peripheral vascular disease, chronic kidney disease, and chronic anemia were significant risk factors of post-PCNL AKI. Corticosteroids and antifungals were associated with increased odds of AKI. Cardiovascular, neurologic complications, sepsis, and prolonged intensive care unit (ICU) stay percentages were higher in AKI patients. Hospital and ICU length of stay was greater in the AKI group. Provided the limited literature regarding postoperative AKI following PCNL, and the detriment that AKI can have on clinical outcomes, it is important to continue studying this topic to better understand how to optimize patient care to address patient- and procedure-specific risk factors.

Initial experience: ex-vivo perfused pig kidney to study urinary oxalate excretion

Existing animal models of renal oxalate excretion utilize either gut or peritoneal cavity for oxalate absorption. Ex vivo renal perfusion is an established tool for graft preservation. We sought to repurpose this concept to study the early pathogenesis of urinary lithiasis. Juvenile female Yorkshire porcine kidneys were removed laparoscopically and placed on an ex vivo cardiopulmonary bypass circuit utilizing whole-blood based perfusate. Pre-defined goals were identified for each attempt (n = 5) with plans to increase physiologic model complexity. Tissue perfusion and oxygenation were monitored by serial perfusate iSTAT testing. Once steady urine production was achieved, aqueous oxalate was injected into the perfusate. Renal outcomes were assessed by histology and blood/urinary assays. After demonstrating proof-of-concept in early trials, normothermic (37 °C) ex vivo whole-blood perfusion with Steen Solution™ was performed exceeding three hours at physiologic mean arterial pressures. Circuit parameters remained in the physiologic range for electrolytes, temperature, mean arterial pressure, lactate, and pH. Urine was produced in three experiments. Urinary filtrate demonstrated consistently higher urine creatinine compared to perfusate, and arterial perfusate oxalate boluses lead to urinary oxalate spikes followed by continuous oxalate clearance. Histopathologic analysis with H&E and Pizzolato's method staining demonstrated formation of calcium oxalate crystals. In light of these promising metabolite clearances, ex vivo porcine renal perfusion appears to be a feasible alternative to study oxalate excretion. Longer validation studies are necessary to establish this technique as a model for kidney stone pathogenesis.

The impact of the number of lifetime stone events on quality of life: results from the North American Stone Quality of Life Consortium

To evaluate the impact of chronic stone recurrence on an individual's quality of life using the validated Wisconsin Stone Quality of Life (WISQOL) questionnaire. We collected cross-sectional data on patients with kidney stones from 14 institutions in North America. A stone event was defined as renal colic, stone-related procedure or emergency department visit. The regression analyses using general linear models and pairwise comparison determined the impact of the number of stone events on quality of life. The median number of stone events among the 2205 patients who completed the questionnaire was 3 (IQR 1-6). The mean total score was 107.4 ± 28.7 (max 140 points). The number of lifetime stone events was an independent predictor of lower quality of life (p < 0.001), specifically, score declined significantly beyond five events. Compared with patients who experienced a single stone event, there was a 0.4, 2.5, and 6.9 point decline in the adjusted mean WISQOL score after 2-5, 6-10, or > 10 events, respectively. The cumulative number of lifetime stone events was associated with a lower quality of life when more than five stone events were occurred. These findings underscore the importance of efforts to determine the underlying metabolic etiology of urolithiasis in the recurrent stone former, and the institution of a regimen to place their stone disease in remission.

Percutaneous Removal of Retained Metallic Ureteral Stent with a Looped Polytetrafluoroethylene-Coated Guidewire

Background: Ureteral stricture disease is a troubling urologic issue that can be managed with surgical reconstruction or, more conservatively, with chronic nephrostomy tubes or ureteral stents. These indwelling tubes require exchanges and are prone to complications such as encrustation or stent failure. Metallic ureteral stents are designed to be more resistant to extrinsic compression and allow for exchanges at longer intervals. However, encrustation or tissue ingrowth can occur with these stents as well. The removal of encrusted or embedded metallic ureteral stents poses a difficult clinical scenario. We present a case of an encrusted metallic stent embedded in a proximal ureteral stricture requiring percutaneous endoscopic removal with a novel looped-wire technique. Case Presentation: A 50-year-old Caucasian man with bilateral ureteral stricture disease, managed with chronic indwelling metallic stents, failed retrograde removal on the right during routine exchange. Staged procedures with percutaneous nephrostomy, followed by combined percutaneous antegrade and retrograde endoscopy were required to observe and access the embedded stent. The exposed metallic surface was unable to be grasped by available instruments through flexible endoscopy. Under endoscopic control with fluoroscopic guidance, a polytetrafluoroethylene (PTFE)-coated guidewire was looped around the metallic stent. With gentle traction on the wire loop, the embedded stent curl was delivered out of the stricture and into the renal pelvis from where it was extracted carefully with graspers inserted through a rigid nephroscope. Follow-up antegrade fluoroscopic studies with contrast showed no extravasation. Conclusion: Percutaneous removal of metallic stents retained within the ureter has unique challenges. We present a novel method of extraction of a retained metallic stent with a looped PTFE-coated guidewire, which may safely and effectively be used in complex situations.

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.

Metabolic Syndrome Negatively Impacts Stone-Specific Quality of Life

Purpose: Metabolic syndrome (MetS) is a cluster of metabolic diseases that is linked to atherosclerotic cardiovascular disease. MetS has also been linked to increased nephrolithiasis. However, limited research has been conducted on MetS and its impact on stone-specific health-related quality of life (HRQOL). This study aims to examine the hypothesis that the presence of MetS is associated with decreased HRQOL. Materials and Methods: The Wisconsin Stone Quality of Life Questionnaire, a stone-specific HRQOL questionnaire, was used to survey 3051 patients with kidney stones. Medical history was collected from patients. These data were used to distinguish MetS patients from non-MetS patients. Among patients with current stones, a Wilcoxon rank sum test was used to compare HRQOL scores from MetS patients and non-MetS patients. HRQOL from patients with and without individual MetS components were also compared, and a multivariate analysis was conducted. Results: Statistical comparison between MetS patients (median score 102/140) and non-MetS patients (median score 106/140) demonstrated a lower stone-specific HRQOL in patients with MetS (p = 0.049). Among individual MetS components, patients with diabetes mellitus (DM) or body mass index (BMI) >30 had significantly lower HRQOL than patients without DM or BMI <30 (p = 0.028 and p < 0.001, respectively). The multivariate analysis supported this trend as MetS remained a significant predictor of decreased HRQOL (p = 0.002) after controlling for other variables assessed. Conclusions: This study indicates an association between MetS and a lower stone-specific QOL. This has important implications for stone prevention strategies in patients with MetS. Clinical Trial Registration number: H14-01143.

Evaluation of Patient Factors That Influence Predictive Formulas for Determining Ureteral Stent Length When Compared to Direct Measurement

Objectives: To compare direct ureteral length measurements with predictive formulas used for the preoperative assessment of ureteral length, and to evaluate patient factors that impact the accuracy of these predictive formulas. Methods: Patients undergoing ureteral stenting for benign and malignant indications were included. Clinical factors analyzed were gender, race, height, weight, prior abdominal or pelvic surgery, radiation therapy, pelvic organ prolapse (POP), laterality, hydronephrosis, and pre-existing ureteral stent. Three predictive formulas and a common height-based formula were used. Direct ureteral measurements were obtained with a ruled 5F ureteral catheter. Predictive formulas were compared with direct ureteral measurements using scatterplot and Spearman's correlation coefficient. Univariate and multivariate logistic regressions were used to evaluate patient factors associated with ≥2 cm deviation from direct ureteral measurements. Results: A total of 108 patients (134 ureters) were analyzed. All predictive formulas correlated poorly with direct ureteral measurements, although as much as 60% of ureteral stent lengths were accurately predicted. Several patient factors significantly impacted accuracy of formulas: male gender (p = 0.04), POP (p = 0.05), body mass index (BMI) ≥25 (p = 0.03), and pre-existing ureteral stent (p = 0.05). Conclusion: Our study suggests that predictive formulas for ureteral stent length have poor accuracy when compared to direct measurement, especially for patients with elevated BMI and POP. Our institution considers direct ureteral measurement the gold standard for determining ureteral stent length-a method that is universally applicable and independent of patient factors.

The effect of travel distance on health-related quality of life for patients with nephrolithiasis

INTRODUCTION

Urolithiasis causes a significant impact on health-related quality of life (HRQOL). Patients with kidney stones have high levels of stress and anxiety. Symptom resolution often requires treatment. Travel distance is a barrier to care but little is known about its effects on HRQOL. We hypothesize that increased distance to treatment site is associated with decreased HRQOL.

METHODS

Patients with a history of stones were enrolled at 11 tertiary centers as part of the QOL Stone Consortium of North America. HRQOL data were obtained using the Wisconsin Stone Quality of Life questionnaire (WISQOL). We calculated distance between patient and treatment site using national ZIP codes. We used linear models to evaluate the effect of distance on HRQOL, while also considering demographics data, stones/symptom status, and distance.

RESULTS

Of the 1676 enrolled patients, 52% were male, 86% non-Latino White, and the mean age was 53 years. Mean distance to treatment site was 63.3 km (range 0-3774), with 74% reporting current stones and 45% current symptoms. WISQOL score and distance were negatively correlated for patients reporting current stones and symptoms (p=0.0010). Linear modelling revealed decreased WISQOL scores for patients with symptoms as distance increased from treatment site (p=0.0001), with a 4.7-point decrease for every 100 km traveled.

CONCLUSIONS

Stone disease imposes significant burden on patients' HRQOL due to a variety of factors. Patients with active stone symptoms report worse HRQOL with increased distance to their treatment site. Possible etiologies include travel burden, increased disease burden, decreased healthcare use, and delays in care.

Long-term Recurrence Rates in Uric Acid Stone Formers With or Without Medical Management

OBJECTIVE

To determine if medical therapy affects long-term clinical outcomes in uric acid stone formers (UASF).

METHODS

We identified 53 UASF who had complete stone clearance following stone procedure by computed tomography (CT) and had ≥1 postoperative 24-hour urine collection and a clinical follow-up ≥6 months with a surveillance CT scan. Patients were divided into "adherent to medical therapy" (compliance with potassium citrate ± allopurinol verified by computerized pharmacy data) or nonadherent groups. Primary outcomes were CT stone recurrence rate and need for surgical stone intervention.

RESULTS

We found 28 of 53 (53%) adherent and 25 of 53 (47%) nonadherent individuals (14 declined medication, 11 intolerant). With median follow-up of 24 months, no significant differences were noted between groups in regards to stone recurrence (32%; P = .99) or in 24-hour urine pH compared to baseline or follow-up (range 5.46-5.62; P = 0.06). Adherent patients, however, had smaller CT stone recurrence sizes (6.3 ± 3.8 vs 11.8 ± 6.2 mm, P = .02), were 28% less likely to require stone surgery compared to those without therapy (P <.01), and trended toward longer time intervals without recurrence (23.1 ± 18.8 vs 10.5 ± 7.5 months, P = .10) compared to nonadherents. Study confounders included a variety of medication dosages and adherences, limited nonadherent follow-up, and small study number.

CONCLUSION

UASF adherent to medical therapy had smaller recurrence sizes and fewer surgical interventions vs nonadherent, highlighting the protective role of potassium citrate in UA stone disease. The comparable urine pH and stone recurrence rates between groups, however, underscore areas for improvement in future UA stone prevention strategies.

The Effect of Thiazide and Potassium Citrate Use on the Health Related Quality of Life of Patients with Urolithiasis

PURPOSE

To our knowledge it is unknown whether the benefits of medical management of urolithiasis outweigh the potential side effects of the medications used, including potassium citrate and thiazide diuretics. Therefore, we evaluated the relationship between potassium citrate or thiazides and overall stone related health related quality of life.

MATERIALS AND METHODS

Cross-sectional data were obtained on stone forming enrollees in the North American Stone Quality of Life Consortium. We used the WISQOL (Wisconsin Stone Quality of Life) questionnaire to compare health related quality of life between patients treated and not treated with potassium citrate or thiazide type diuretics. Additionally, the likelihood of gastrointestinal complaints was compared between those prescribed and not prescribed potassium citrate. The likelihood of fatigue and sexual complaints was also compared in those prescribed and not prescribed thiazides.

RESULTS

Of the 1,511 subjects, including 787 males and 724 females, 279 were on potassium citrate and 238 were on thiazides at study enrollment. Patients prescribed potassium citrate had higher health related quality of life in each domain vs those not prescribed potassium citrate (p <0.001). Patients prescribed thiazides had higher health related quality of life in each domain compared to those not prescribed thiazide (all p <0.01). Those prescribed potassium citrate were less likely than those not prescribed potassium citrate to report nausea, stomach upset or cramps (OR 0.57, p <0.001). Patients prescribed thiazides were less likely than those not prescribed thiazides to report fatigue (OR 0.63, p = 0.004) or reduced sexual interest and/or activity (OR 0.64, p = 0.005).

CONCLUSIONS

Among stone formers the use of potassium citrate and thiazides was associated with better health related quality of life across all WISQOL domains without an increased likelihood of gastrointestinal complaints and fatigue or sexual complaints, respectively. These findings may be useful when counseling patients regarding the initiation of potassium citrate or thiazides for medical management of nephrolithiasis.

Pseudomonas aeruginosa as an Etiologic Agent of Nephrolithiasis in Deep Water Divers

Background: A number of occupations and professions may be associated with unique hazards relevant to urologic care.

Case Presentation: We relate the presentation, care, and the occupational hazard of urinary tract infection (UTI), presenting as cystitis and pyelonephritis, with stone formation in a scuba diver. The patient voiced concern that his diving suit malfunction was related to his UTI and stone disease. We review the risk of UTI in the diving environment. We also report the development of infection-related stone in this case. Our evaluation included consultation with an expert in diving and associated equipment.

Conclusion: Careful installation of P-valves in dry suits, proper maintenance, and monitoring for leakage improved post-dive hygiene, and proper maintenance of P-valve tubing and diving equipment may decrease the incidence of these complications described. Urologists treating UTI and stone disease should be aware of this occupation-related hazard.

Multicenter External Validation and Comparison of Stone Scoring Systems in Predicting Outcomes After Percutaneous Nephrolithotomy

BACKGROUND AND PURPOSE

Several scoring systems have recently emerged to predict stone-free rate (SFR) and complications after percutaneous nephrolithotomy (PCNL). We aimed to compare the most commonly used scoring systems (Guy's stone score, S.T.O.N.E. nephrolithometry, and CROES nomogram), assess their predictive accuracy for SFR and other postoperative variables, and develop a risk group stratification based on these scoring systems.

MATERIALS AND METHODS

We performed a retrospective review of patients who have had a PCNL at four academic institutions between 2006 and 2013. Primary outcome was SFR within 3 weeks of the surgery and secondary outcomes were operative time (OT), complications, and length of stay (LOS). We performed chi-squared, t-test, logistic, linear, and Poisson regressions, as well as receiver operating characteristics curve with area under the curve (AUC) calculation.

RESULTS

We identified 586 patients eligible for analysis. Of these, 67.4% were stone free. Guy's, S.T.O.N.E., and CROES score were predictive of SFR on multivariable logistic regression (odds ratio [OR]: 1.398, 95% confidence interval [CI]: 1.056, 1.852, p = 0.019; OR: 1.417, 85% CI: 1.231, 1.631, p < 0.001; OR: 0.993, 95% CI: 0.988, 0.998, p = 0.004) and have similar predictive accuracy with AUCs of 0.629, 0.671, and 0.646, respectively. On multivariable linear regression, only S.T.O.N.E. was an independent predictor of longer OT (β = 14.556, 95% CI: 12.453, 16.660, p < 0.001). None of the scores were independent predictors of postoperative complications or a longer LOS. Poisson regression allowed for risk group stratification and showed the S.T.O.N.E. score and CROES nomogram to have the most distinct risk groups.

CONCLUSIONS

The three evaluated scoring systems have similar predictive accuracy of SFR. S.T.O.N.E. has additional value in predicting OT. Risk group stratification can be used for patient counseling. Further research is needed to identify whether or not any is superior to the others with regard to clinical usefulness and predictive accuracy.

Calcium Oxalate Stone Fragment and Crystal Phagocytosis by Human Macrophages

PURPOSE

In murine and human hyperoxaluric conditions macrophages can be seen surrounding renal calcium oxalate crystal deposits. We hypothesized that macrophages have a role in degrading and destroying these deposits. We investigated the inflammatory response and phagocytic mechanisms when macrophages were exposed to human kidney stones and inorganic crystals.

MATERIALS AND METHODS

Human monocytes were differentiated into resting, fully differentiated macrophages by treatment with recombinant human macrophage colony-stimulating factor (M-CSF) or GM-CSF (granulocyte M-CSF) for 6 days. After confirming phenotype by flow cytometry the macrophages were exposed for 20 hours to fragments of sterile human calcium oxalate stones or calcium oxalate crystals. Crystal uptake was determined, and supernatant cytokine and chemokine profiles were analyzed using antibody arrays. Quantitative reverse transcriptase-polymerase chain reaction was done to validate mRNA profile expression.

RESULTS

Under direct vision fluorescence microscopy activated human macrophages were noted to surround stone fragments and synthesized crystals, and destroy them in a step-by-step process that involved clathrin mediated endocytosis and phagocytosis. An inflammatory cascade was released by macrophages, including the chemokines chemokine ligand (CCL)2, CCL3, interleukin (IL)-1 receptor antagonist (IL-1ra), complement component C5/C5a and IL-8. Response patterns to stone and crystal material depended on macrophage phenotype and activation status.

CONCLUSIONS

In our in vitro study macrophages differentiated with M-CSF showed greater ability to phagocytize crystal deposits than those treated with GM-CSF. Following clathrin mediated endocytosis macrophages released a number of cytokines that are crucial for the inflammatory immune response. This suggests that tissue macrophages have an important role in preventing kidney stone disease by removing and digesting interstitial renal crystal deposits.

Low methodological and reporting quality of randomized, controlled trials of devices to treat urolithiasis

PURPOSE

We assessed the methodological and reporting quality of randomized, controlled trials of stone disease management and determined whether the reporting quality of randomized, controlled trials improved with time.

MATERIALS AND METHODS

We systematically searched the literature for randomized, controlled trials of urolithiasis treatment. We developed and pilot tested a data extraction checklist based on CONSORT (Consolidated Standards of Reporting Trials) criteria as well as a clinical checklist relevant to urolithiasis, each scored as 0 to 25. Our primary outcome measures were the mean differences in CONSORT and clinical summary scores with time. We performed statistical hypothesis testing using the Student t-test with 2-sided α = 0.05 to compare scores between 2002 to 2006 and 2007 to 2011.

RESULTS

A total of 104 randomized, controlled trials met study inclusion criteria. The most common procedure types studied were percutaneous nephrolithotomy (41.3%), ureteral stenting (28.8%) and shock wave lithotripsy (25.0%). Mean ± SE CONSORT summary scores were 11.4 ± 0.4 and 12.1 ± 0.3 in 2002 to 2006 and 2007 to 2011, respectively, with a mean difference of 0.7 (95% CI -0.3-1.6, p = 0.167). Mean clinical summary scores were 7.4 ± 0.5 and 9.3 ± 0.4 in 2002 to 2006 and 2007 to 2011, respectively, with a mean difference of 1.8 (95% CI 0.6-3.1, p = 0.004).

CONCLUSIONS

While the number of randomized, controlled trials of urological devices used to treat stone disease substantially increased with time, methodological and clinical reporting quality remains suboptimal. This compromises their credibility and warrants efforts to promote appropriate performance of future endourological studies.

Clinical, pathologic, and functional outcomes after nephron-sparing surgery in patients with a solitary kidney: a multicenter experience

BACKGROUND AND PURPOSE

Surgical management of a renal neoplasm in a solitary kidney is a balance between oncologic control and preservation of renal function. We analyzed patients with a renal mass in a solitary kidney undergoing nephron-sparing procedures to determine perioperative, oncologic, and renal functional outcomes.

PATIENTS AND METHODS

A multicenter study was performed from 12 institutions. All patients with a functional or anatomic solitary kidney who underwent nephron-sparing surgery for one or more renal masses were included. Tumor size, complications, and recurrence rates were recorded. Renal function was assessed with serum creatinine level and estimated glomerular filtration rate.

RESULTS

Ninety-eight patients underwent 105 ablations, and 100 patients underwent partial nephrectomy (PN). Preoperative estimated glomerular filtration rate (eGFR) was similar between the groups. Tumors managed with PN were significantly larger than those managed with ablation (P<0.001). Ablations were associated with a lower overall complication rate (9.5% vs 24%, P=0.01) and higher local recurrence rate (6.7% vs 3%, P=0.04). Eighty-four patients had a preoperative eGFR ≥60 mL/min/1.73 m(2). Among these patients, 19 (23%) fell below this threshold after 3 months and 15 (18%) at 12 months. Postoperatively, there was no significant difference in eGFR between the groups.

CONCLUSIONS

Extirpation and ablation are both reasonable options for treatment. Ablation is more minimally invasive, albeit with higher recurrence rates compared with PN. Postoperative renal function is similar in both groups and is not affected by surgical approach.

Laparoscopic-Guided Radiofrequency Ablation is Safe for the Treatment of Enhancing Renal Masses Among Patients Prescribed Antithrombotic Agents

Patients undergoing laparoscopic-guided radiofrequency ablation (LRFA) for the treatment of a renal mass are commonly prescribed antithrombotic agents for the management of comorbid medical diseases. We retrospectively evaluated the safety of LRFA in this group. From October 2005 to June 2010, 109 patients underwent LRFA. Antithrombotic therapy was prescribed to 52 of these patients. Agents were managed the week of surgery per current practice guidelines from the American College of Chest Physicians. Intraoperatively, patients prescribed at least one antithrombotic agent lost a median of 10 mL of blood, while patients not on an antithrombotic agent also lost 10 mL of blood (P = .828). Both groups had a similar rate of procedure-related complications (intraoperative, P = 1.00; postoperative, P = .673). No patient required a blood transfusion or experienced a postoperative thromboembolic event. In conclusion, when current practice guidelines are followed, LRFA is safe among patients prescribed antithrombotic agents.

Molecular characterization of kidney cancer: association of hyaluronic acid family with histological subtypes and metastasis

BACKGROUND

Molecular profiling of renal cell carcinomas (RCCs) may improve the distinction between oncocytoma and malignant RCC subtypes and aid in early detection of metastasis. The hyaluronic acid (HA) family includes HA synthases (HAS1, HAS2, HAS3), hyaluronidases (HYAL-1, HYAL-2, HYAL-3, HYAL-4, PH20, HYAL-P1), and HA receptors (CD44s, CD44v, RHAMM). HA family members promote tumor growth and metastasis. The authors evaluated the expression of HA family members in kidney specimens.

METHODS

By using quantitative polymerase chain reaction, mRNA levels of 12 HA family members were measured in tumor specimens obtained from 86 consecutive patients undergoing nephrectomy; 80 of them also provided normal specimens. Mean and median follow-up were 15.2 ± 8.8 and 13.8 months. RCC specimens included clear cell RCC: 65; papillary: 10; chromophobe: 5; oncocytoma: 6; metastasis positive: 17.

RESULTS

Median HAS1, CD44s, and RHAMM transcript levels were elevated 3- to 25-fold in clear cell RCC and papillary and chromophobe tumors when compared with normal tissues. HYAL-4, CD44s, and RHAMM levels were elevated 4- to 12-fold in clear cell RCC and papillary tumors when compared with oncocytomas; only HYAL-4 levels distinguished between chromophobe and oncocytoma (P = .009). CD44s and RHAMM levels were significantly higher in tumors <4 cm (510 ± 611 and 19.6 ± 20.8, respectively) when compared with oncocytoma (46.4 ± 20 and 3.8 ± 2.5; P ≤ .006). In univariate and multivariate analyses, CD44s (P < .0001), RHAMM (P < .0001), stage, tumor size, and/or renal vein involvement were significantly associated with metastasis. The combined CD44s + RHAMM marker had 82% sensitivity and 86% specificity to predict metastasis.

CONCLUSIONS

CD44s and RHAMM levels distinguish between oncocytoma and RCC subtypes regardless of tumor size and are potential predictors of RCC metastasis.

Surgical management of upper tract urothelial carcinoma

Upper tract urothelial cell carcinoma accounts for 5% of all urothelial tumors. Compared to lower urinary tract tumors, upper tract urothelial carcinoma is diagnosed more frequently at advanced stages. Open radical nephroureterectomy remains the gold standard treatment option for upper tract tumors. However, with the advancement of minimally invasive techniques and the benefits of these procedures regarding perioperative morbidity, cosmesis, and earlier convalescence, these options have shown promise in managing the patients with upper tract urothelial carcinoma. Despite the perioperative advantages, concerns exist on the oncological safety after minimally invasive surgery. In this article, we provide a comprehensive overview of the surgical management of upper tract urothelial carcinoma.

Initial clinical experience with use of ureteral access sheaths in the diagnosis and treatment of upper tract urothelial carcinoma

OBJECTIVE

To describe our experience with ureteral access sheaths in the diagnosis and treatment of upper tract urothelial carcinoma.

METHODS

We retrospectively identified a patient cohort who underwent ureteroscopy for suspicion of upper tract urothelial carcinoma and identified those with placement of a ureteral access sheath. Records were reviewed for demographic information, comorbidity data, operative complications, and pathology results. The histologic grade of ureteroscopic biopsies and nephroureterectomy specimens were evaluated for concordance.

RESULTS

A total of 125 patients underwent 235 procedures for known or suspected upper tract urothelial carcinoma. Access sheaths were used in patients in whom significant urothelial lesions were noted in the proximal upper urinary tract. A total of 64 patients underwent 85 sheath-inclusive procedures. Sheath deployment was successful in 83 (97.6%) of the 85 procedures. Biopsies yielded specimen adequate for histopathologic diagnosis in 75 (90.4%) of 83 cases. No ureteral access sheath-related complications were noted. Of the 125 patients, 34 underwent removal of 35 renal units. The concordance of tumor grade between biopsy and nephroureterectomy specimens was 88.6% (P=.0002).

CONCLUSION

Ureteral access sheaths are safe for use in the diagnosis and treatment of upper tract urothelial carcinoma. Sheath placement facilitated the acquisition of multiple biopsy specimens adequate for histopathologic evaluation. Our technique precluded the need for repeat ureteroscopy to establish a diagnosis. Biopsies obtained through an access sheath were highly predictive of tumor grade in nephroureterectomy specimens.

Technical modification for laparoscopic donor nephrectomy to minimize testicular pain: a complication with significant morbidity

The laparoscopic approach to donor nephrectomy is becoming increasingly common. While it is felt that the recovery from laparoscopic nephrectomy is quicker and less painful, a number of complications have been reported. A rarely reported on complication in the literature with significant morbidity is ipsilateral orchalgia. From 1998 to 2008, 257 hand-assisted laparoscopic donor nephrectomies were performed at our institution. Eight of 129 (6.2%) men complained of de novo ipsilateral orchalgia postoperatively. The average duration of pain was 402 days. Patients reported significant morbidity related to this complication. None, however, required further treatment. Three patients reported that they would reconsider organ donation as a result of testicular pain. Our technique originally included dissection and ligation of the gonadal vein en bloc with the ureter at the level of the left common iliac artery. Since recognizing this complication, we have adopted a gonadal vein sparing approach so as not to disturb the vessel below its point of ligation at the renal vein. To date, 50 patients have undergone the modified technique without experiencing orchalgia. In conclusion, ipsilateral testicular pan is a relatively frequent complication of laparoscopic donor nephrectomy and may be a source of significant morbidity. Using a modified surgical technique, this complication can be reduced or eradicated.

Flexible ureterorenoscopy and holmium laser lithotripsy for the management of renal stone burdens that measure 2 to 3 cm: a multi-institutional experience

BACKGROUND AND PURPOSE

Percutaneous nephrostolithotomy (PCNL) is the current standard of care for management of large renal stones (>2 cm). Recent studies have evaluated flexible ureterorenoscopy (URS)/holmium laser lithotripsy as an alternative treatment for patients with contraindications to or preference against PCNL. Stones in an intermediate size range (2-3 cm) may be most amenable to URS/laser lithotripsy as definitive treatment in a single stage. We report a multi-institutional series of URS/laser lithotripsy for renal stone burdens that measure 2 to 3 cm.

PATIENTS AND METHODS

Patients who underwent URS/holmium laser lithotripsy for renal stones that measured 2 to 3 cm were identified retrospectively at three tertiary care centers. Demographic information, disease characteristics, and perioperative and postoperative data were gathered. Patients with renal stone burdens of 2 to 3 cm who were treated by URS/laser lithotripsy and had at least one postoperative visit and imaging study were included. Stone clearance was evaluated using 0-2 mm and <4 mm residual stone burden on postoperative imaging.

RESULTS

One hundred and twenty patients underwent URS/holmium laser lithotripsy for renal stones of 2 to 3 cm. Mean stone burden was 2.4 cm, and mean body mass index was 29.3 kg/m². Indications for URS/laser lithotripsy vs PCNL included patient preference (57), technical or anatomic factors (24), patient comorbidities (17), failed shockwave lithotripsy (9), patient body habitus (3), solitary kidney (3), chronic renal insufficiency (3), and strict anticoagulation (2). Thirty-one (26%) patients had stent placement preprocedure, and 94 (78%) patients underwent outpatient surgery. A ureteral access sheath was used in 67%. One hundred and one (84%) patients underwent single-stage procedures. There was one intraoperative complication (ureteral perforation), and there were eight minor postoperative complications (6.7%). The reoperation rate through the mean 18-month follow-up was 3/120 or 2.5%. Seventy-six (63%) patients had residual stone burden of 0 to 2 mm, and 100 (83%) patients had residual burden of <4 mm.

CONCLUSIONS

We demonstrate that single-stage URS/holmium laser lithotripsy is effective for management of renal stones that measure 2 to 3 cm through intermediate follow-up. Staged procedures can be used selectively for technical reasons or disease factors. Although PCNL achieves superior stone clearance overall, URS/laser lithotripsy is a viable treatment option for selected patients.

Differentiation of oncocytoma and renal cell carcinoma in small renal masses (<4 cm): the role of 4-phase computerized tomography

PURPOSE

We investigate the use of 4-phase computerized tomography with intravenous contrast to help distinguish oncocytoma from renal cell carcinoma (RCC) in tumors <4 cm.

METHODS

We retrospectively identified patients who underwent surgical management for renal tumors <4 cm from 2005 to 2008. Patients who had pre-operative CT evaluation as per our institution's renal mass protocol and had confirmed pathological diagnosis of either oncocytoma or RCC were included in the study. Enhancement readings were obtained for the tumor and the renal cortex using the same slice simultaneously.

RESULTS

Our cohort involved 69 patients (46 men, 23 women; mean age 66) who presented with 79 renal masses. Histopathologically 40 were clear cell, 22 papillary, 5 chromophobe RCC and 12 oncocytoma. On the arterial, venous and delayed phase images, oncocytoma showed the highest mean enhancement change, i.e.,546, 396 and 239% followed by clear cell RCC 261, 261 and 174%, chromophobe RCC 147, 127 and 66% and papillary RCC 137, 184 and 118%, respectively. The enhancement pattern differed significantly on comparing oncocytoma with RCC (P < 0.007). The mean percentage contrast excreted at the end of the delayed phase was 33.3, 13.8, 32 and 53% for clear cell, papillary, chromophobe and oncocytoma, respectively.

CONCLUSION

The enhancement and washout values in Hounsfield units obtained by multiphasic CT scan aid in distinguishing oncocytoma from the commonly seen subtypes of RCC in renal masses <4 cm. This preliminary study demonstrates that arterial phase enhancement greater than 500% and washout values of greater than 50% are exclusively seen in renal oncocytomas.

Living donor nephrectomy: University of Miami technique and current results

OBJECTIVES

Living-donor nephrectomy has significantly expanded the pool of renal transplant donors, allowing for a marked increase in transplantation. Improvements in antirejection medications and refinement of donor selection criteria have allowed for extremely favorable rates of graft survival. More recently, laparoscopic donor nephrectomy (LDN) has significantly reduced the morbidity of renal transplantation in the donor population. The University of Miami/Jackson Memorial Hospital Transplant Center performs a large number of living-donor nephrectomies, with increasing use of LDN and here we report our cumulative experience.

METHODS

A retrospective review was performed of all live donor nephrectomies performed over the last 10 years, including LDN. Surgical complications, both minor and major, were ascertained. Conversion from LDN to open was similarly noted. Follow up, including creatinine one year post-transplant was recorded in open donor nephrectomy (ODN) and LDN groups.

RESULTS

Over 10 years, 413 live donor nephrectomies were performed. Of these, 257 were LDN, and 156 were ODN. In two cases, LDN was converted to ODN. Three patients needed reoperation after donor nephrectomy. There were no perioperative mortalities or deep venous thrombosis. Minor complications, including hernia, fever, and C. difficile diarrhea were very rare, the most common being testicular pain in eight patients.

CONCLUSION

Our extensive experience with living donor nephrectomy, with 413 cases spanning ten years, has been very favorable. The risk of major complications was extremely low, with six reported in the series. Minor complications were similarly rare. Living donor nephrectomy is a safe and feasible method of increasing the number of renal transplantation donors with minimal morbidity.

A renal protocol for all ages and all indications: mercapto-acetyl-triglycine (MAG3) with simultaneous injection of furosemide (MAG3-F0): a 17-year experience

Current clinical requirements mandate the existence of a renal diuretic protocol, which is fast and easy, applicable in all ages and for all indications, convenient for both the patient and the technologist, and provides diagnostic as well as prognostic information. Seventeen years ago a 25-minute protocol, after oral hydration, with no bladder catheterization, and simultaneous injection of mercapto-acetyl-triglycine (MAG(3)) and furosemide (MAG(3)-F(0)), was initiated. It initially was used for the evaluation of drainage and emerged as a protocol to also evaluate the renal parenchyma. Results of this protocol have been published individually, per clinical application. MAG(3)-F(0) was instrumental in the evaluation and prognosis of congenital disorders. For obstruction, in the newborn, an increasing renogram mandates intervention, whereas a downsloping one predicts spontaneous resolution. In children or adults, preoperatively or postoperatively, when the cortex was visualized and drained normally, there was no obstruction, even if urine was retained within a dilated collecting system or an extrarenal pelvis. For diseases of the renal parenchyma, the protocol enabled the diagnosis of acute pyelonephritis (APN) revealing the "regional parenchymal dysfunction," diagnostic of APN. Diffuse parenchymal diseases were characterized by increased residual cortical activity (RCA), and their progression was manifested as a deterioration of RCA. End-stage renal disease was characterized by lack of accumulation and retention. Trauma and leaks were identified with specific patterns. In renovascular hypertension (RVH), an increase in RCA after angiotension-converting enzyme inhibitors is diagnostic of RVH and prognostic of the beneficial effect of angioplasty on hypertension. In renal colic, stratification was possible into (1) complete or severe obstruction requiring immediate intervention, (2) mild obstruction allowing waiting, (3) spontaneous decompression (stunned kidney), and (4) no recent obstruction. In transplants, it enabled differentiation of acute tubular necrosis, acute or chronic rejection and nephrotoxicity, and identified infarcts, RVH, leaks and obstruction. Finally, this method allows for a quick semiquantification of renal function. The clinical usefulness of the MAG(3)-F(0) protocol in most congenital or acquired renal problems is proven through long-term clinical experience and has resulted in a substantial utilization of the test at our Center.

Management of renal masses with laparoscopic-guided radiofrequency ablation versus laparoscopic partial nephrectomy

BACKGROUND AND PURPOSE

Laparoscopic-guided radiofrequency ablation (LRFA) has been introduced as a minimally invasive nephron-sparing management option for renal tumors. Many patients who desire treatment present with multiple comorbidities, which poses a therapeutic challenge. Our purpose is to determine if multipass LRFA is comparable, in terms of surgical risk and immediate postoperative outcomes, to laparoscopic partial nephrectomy (LPN).

PATIENTS AND METHODS

A retrospective study identified 36 and 33 patients who underwent LRFA and LPN, respectively. Perioperative demographic data, tumor characteristics, and follow-up data were evaluated. Statistical analysis was performed using the Student t test and chi-square analysis.

RESULTS

Age, American Society of Anesthesiology score, and Charlson Comorbidity Index were significantly higher in the LRFA group than the LPN group (P < 0.001). Average tumor size was 2.8 cm and 3.1 cm for the LRFA and LPN groups, respectively. There were no significant differences in change between the preoperative and postoperative creatinine/glomerular filtration rate values or perioperative complication rates for the groups. Estimated blood loss and length of stay were significantly lower for the LRFA group than the LPN group (P < 0.05). Follow-up ranged 6 to 23 months and 6 to 58 months for the LRFA and the LPN groups, respectively. There has been no evidence of tumor recurrence in the follow-up period.

CONCLUSIONS

We present our initial report comparing patients undergoing LRFA v LPN for the management of renal tumors. Our preliminary results with our experience with multipass laparoscopic-guided RFA demonstrate that this technique can be safely used in an elderly, higher risk population. Long-term follow-up is needed to determine oncologic efficacy.