Percutaneous nephrolithotomy vs retrograde intrarenal surgery for renal stones: a Cochrane Review.

OBJECTIVES: To assess the effects of percutaneous nephrolithotomy (PCNL) vs retrograde intrarenal surgery (RIRS) for the treatment of renal stones in adults. METHODS: We performed a comprehensive search of the Cochrane Library, MEDLINE, Embase, three other databases, trials registries, other sources of the grey literature, and conference proceedings up to 23 March 2023. We applied no restrictions on publication language or status. Screening, data extraction, risk-of-bias assessment, and certainty of evidence (CoE) rating using the Grading of Recommendations Assessment, Development and Evaluations (GRADE) approach were done in duplicate by two independent reviewers. This co-publication focuses on the primary outcomes of this review only. RESULTS: We included 42 trials that met the inclusion criteria. Stone-free rate (SFR): PCNL may improve SFRs (risk ratio [RR] 1.13, 95% confidence interval [CI] 1.08-1.18; I2 = 71%; 39 studies, 4088 participants; low CoE). Major complications: PCNL probably has little to no effect on major complications (RR 0.86, 95% CI 0.59-1.25; I2 = 15%; 34 studies, 3649; participants; moderate CoE) compared to RIRS. Need for secondary interventions: PCNL may reduce the need for secondary interventions (RR 0.31, 95% CI 0.17-0.55; I2 = 61%; 21 studies, 2005 participants; low CoE) compared to RIRS. CONCLUSION: Despite shortcomings in most studies that lowered our certainty in the estimates of effect to mostly very low or low, we found that PCNL may improve SFRs and reduce the need for secondary interventions while not impacting major complications. Ureteric stricture rates may be similar compared to RIRS. We expect the findings of this review to be helpful for shared decision-making about management choices for individuals with renal stones.

Tranexamic acid for percutaneous nephrolithotomy: an abridged Cochrane review.

OBJECTIVE: To assess the effects of tranexamic acid (TXA) in individuals with kidney stones undergoing percutaneous nephrolithotomy (PCNL). PATIENTS AND METHODS: We performed a literature search of Cochrane Library, PubMed (including MEDLINE), Embase, Scopus, Global Index Medicus, trials registries, grey literature, and conference proceedings. We included randomised controlled trials (RCTs) that compared treatment with PCNL with administration of TXA to placebo (or no TXA) for patients aged ≥18 years. Two review authors independently classified studies and abstracted data. Primary outcomes were blood transfusion, stone-free rate (SFR), thromboembolic events (TEE). We rated the certainty of evidence (CoE) according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach using a minimally contextualised approach with pre-defined thresholds for minimally clinically important differences (MCID). RESULTS: We included 10 RCTs assessing the effect of systemic TXA in PCNL vs placebo (or no TXA). Eight studies were published as full text. Based on an adjusted baseline risk of blood transfusion of 5.7%, systemic TXA may reduce blood transfusions (risk ratio [RR] 0.45, 95% confidence interval [CI] 0.27-0.76). Based on an adjusted baseline SFR of 75.7%, systemic TXA may increase SFR (RR 1.11, 95% CI 0.98-1.27). There is probably no difference in TEEs (risk difference 0.001, 95% CI -0.01 to 0.01). Systemic TXA may increase adverse events (AEs) (RR 5.22, 95% CI 0.52-52.72). Systemic TXA may have little to no effect on secondary interventions (RR 1.15, 95% CI 0.84-1.57). The CoE for most outcomes was assessed as low or very low. CONCLUSIONS: Based on a body of evidence of 10 RCTs, we found that systemic TXA in PCNL may reduce blood transfusions, major surgical complications, and hospital length of stay, as well as improve the SFR; however, it may increase AEs. These findings should inform urologists and their patients in making informed decisions about the use of TXA in the setting of PCNL.

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.

Percutaneous nephrolithotomy versus retrograde intrarenal surgery for treatment of renal stones in adults.

BACKGROUND: Kidney stones (also called renal stones) can be a source of pain, obstruction, and infection. Depending on size, location, composition, and other patient factors, the treatment of kidney stones can involve observation, shock wave lithotripsy, retrograde intrarenal surgery (RIRS; i.e. ureteroscopic approaches), percutaneous nephrolithotomy (PCNL), or a combination of these approaches. OBJECTIVES: To assess the effects of percutaneous nephrolithotomy (PCNL) versus retrograde intrarenal surgery (RIRS) for the treatment of renal stones in adults. SEARCH METHODS: We performed a comprehensive search of the Cochrane Library, MEDLINE, Embase, Scopus, and two trials registries up to 23 March 2023. We applied no restrictions on publication language or status. SELECTION CRITERIA: We included randomized controlled trials that evaluated PCNL (grouped by access size in French gauge [Fr] into three groups: ≥ 24 Fr [standard PCNL], 15-23 Fr [mini-PCNL and minimally invasive PCNL], and < 15 Fr [ultra-mini-, mini-micro-, super-mini-, and micro-PCNL]) versus RIRS. DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies and extracted data from the included studies. Our primary outcomes were stone-free rate, major complications, and need for secondary interventions. Our main secondary outcomes were unplanned medical visits to emergency/urgent care or outpatient clinic, length of hospital stay, ureteral stricture or injury, and quality of life. We performed statistical analyses using a random-effects model. We rated the certainty of evidence using GRADE criteria. We adopted a minimally contextualized approach with predefined thresholds for minimal clinically important differences (MCIDs). MAIN RESULTS: We included 42 trials assessing the effects of PCNL versus RIRS in 4571 randomized participants. Twenty-two studies were published as full-text articles, and 20 were published as abstract proceedings. The average size of stones ranged from 10.1 mm to 39.1 mm. Most studies did not report sources of funding or conflicts of interest. The main results for the most important outcomes are summarized below. Stone-free rate PCNL compared with RIRS may improve stone-free rates (risk ratio [RR] 1.13, 95% confidence interval [CI] 1.08 to 1.18; I2 = 71%; 39 studies, 4088 participants; low-certainty evidence). Based on 770 participants per 1000 being stone-free with RIRS, this corresponds to 100 more (62 more to 139 more) stone-free participants per 1000 with PCNL (an absolute difference of 10%, where the predefined MCID was 5%). Major complications PCNL compared with RIRS probably has little or no effect on major complications (RR 0.86, 95% CI 0.59 to 1.25; I2 = 15%; 34 studies, 3649 participants; moderate-certainty evidence). Based on 31 complications in the RIRS group, this corresponds to six fewer (13 fewer to six more) major complications per 1000 with PCNL (an absolute difference of 0.6%, where the predefined MCID was 2%). Need for secondary interventions PCNL compared with RIRS may reduce the need for secondary interventions (RR 0.31, 95% CI 0.17 to 0.55; I2 = 61%; 21 studies, 2005 participants; low-certainty evidence). Based on 222 secondary interventions in the RIRS group, this corresponds to 153 fewer (185 fewer to 100 fewer) secondary interventions per 1000 with PCNL (an absolute difference of 15.3%, where the predefined MCID was 5%). Unplanned medical visits No studies reported unplanned medical visits. Length of hospital stay PCNL compared with RIRS may extend length of hospital stay (mean difference 1.04 days more, 95% CI 0.27 more to 1.81 more; I2 = 100%; 26 studies, 2804 participants; low-certainty evidence). This effect size is greater than the predefined MCID of one day. Ureteral stricture or injury PCNL compared with RIRS may have little or no effect on the occurrence of ureteral strictures (RR 0.93, 95% CI 0.39 to 2.21; I2 = 0%; 13 studies, 1574 participants; low-certainty evidence). Based on 14 ureteral strictures in the RIRS group, this corresponds to one fewer (nine fewer to 17 more) ureteral strictures per 1000 with PCNL (an absolute difference of 0.1%, where the predefined MCID was 2%). Quality of life No studies reported quality of life. AUTHORS' CONCLUSIONS: Based on a large body of evidence from 42 trials, we found that PCNL compared with RIRS may improve stone-free rates and may reduce the need for secondary interventions, but probably has little or no effect on major complications. PCNL compared with RIRS may have little or no effect on ureteral stricture rates and may increase length of hospital stay. We found no evidence on unplanned medical visits or participant quality of life. Because of the considerable shortcomings of the included trials, the evidence for most outcomes was of low certainty. Access size for PCNL was less than 24 Fr in most studies that provided this information. We expect the findings of this review to be helpful for shared decision-making about management choices for individuals with renal stones.

Tranexamic acid for percutaneous nephrolithotomy.

BACKGROUND: Percutaneous nephrolithotomy (PCNL) is the gold standard for the treatment of large kidney stones but comes with an increased risk of bleeding compared to other treatments, such as ureteroscopy and shock wave lithotripsy. Tranexamic acid (TXA) is an antifibrinolytic agent that has been used to reduce bleeding complications in other settings. OBJECTIVES: To assess the effects of TXA in individuals with kidney stones undergoing PCNL. SEARCH METHODS: We performed a comprehensive literature search of the Cochrane Library, PubMed (including MEDLINE), Embase, Scopus, Global Index Medicus, trials registries, other sources of the grey literature, and conference proceedings. We applied no restrictions on the language of publication nor publication status. The latest search date was 11 May 2023. SELECTION CRITERIA: We included randomized controlled trials (RCTs) that compared treatment with PCNL with administration of TXA to placebo (or no TXA) for patients ≥ 18 years old. DATA COLLECTION AND ANALYSIS: Two review authors independently classified studies and abstracted data. Primary outcomes were: blood transfusion, stone-free rate (SFR), and thromboembolic events (TEEs). Secondary outcomes were: adverse events (AEs), secondary interventions, major surgical complications, minor surgical complications, unplanned hospitalizations or readmissions, and hospital length of stay (LOS). We performed statistical analyzes using a random-effects model. We rated the certainty of evidence (CoE) according to the GRADE approach using a minimally contextualized approach with predefined thresholds for minimally clinically important differences (MCIDs). MAIN RESULTS: We analyzed 10 RCTs assessing the effect of systemic TXA in PCNL versus placebo (or no TXA) with 1883 randomized participants. Eight studies were published as full text. One was published in abstract proceedings, but it was separated into two separate studies for the purpose of our analyzes. Average stone surface area ranged 3.45 to 6.62 cm2. We also found a single RCT published in full text assessing the effects of topical TXA in PCNL versus placebo (or no TXA) with 400 randomized participants, the results of which are further described in the review. Here we focus only on the results of TXA used systemically. Blood transfusion - Based on a representative baseline risk of 5.7% for blood transfusions taken from a large presentative observational studies, systemic TXA may reduce blood transfusions (risk ratio (RR) 0.45, 95% confidence interval (CI) 0.27 to 0.76; I2 = 28%; 9 studies, 1353 participants; low CoE). We assumed an MCID of ≥ 2%. Based on 57 participants per 1000 with placebo (or no TXA) being transfused, this corresponds to 31 fewer (from 42 fewer to 14 fewer) participants being transfused per 1000. Stone-free rate - Based on a representative baseline risk of 75.7% for SFR, systemic TXA may increase SFRs (RR 1.11, 95% CI 0.98 to 1.27; I2 = 62%; 4 studies, 603 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 757 participants per 1000 being stone free with placebo (or no TXA), this corresponds to 83 more (from 15 fewer to 204 more) stone-free participants per 1000. Thromboembolic events - There is probably no difference in TEEs (risk difference (RD) 0.00, 95% CI -0.01 to 0.01; I2 = 0%; 6 studies, 841 participants; moderate CoE). We assumed an MCID of ≥ 2%. Since there were no thromboembolic events in intervention and/or control groups in 5 out of6 studies, we opted to assess a risk difference with systemic TXA for this outcome. Adverse events - Systemic TXA may increase AEs (RR 5.22, 95% CI 0.52 to 52.72; I2 = 75%; 4 studies, 602 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 23 participants per 1000 with placebo (or no TXA) having an adverse event, this corresponds to 98 more (from 11 fewer to 1000 more) participants with adverse events per 1000. Secondary interventions - Systemic TXA may have little to no effect on secondary interventions (RR 1.15, 95% CI 0.84 to 1.57; I2 = 0%; 2 studies, 319 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 278 participants per 1000 with placebo (or no TXA) having a secondary intervention, this corresponds to 42 more (from 44 fewer to 158 more) participants with secondary interventions per 1000. Major surgical complications - Based on a representative baseline risk for major surgical complications of 4.1%, systemic TXA may reduce major surgical complications (RR 0.36, 95% CI 0.21 to 0.62; I2 = 0%; 5 studies, 733 participants; moderate CoE). We assumed an MCID of ≥ 2%. Based on 41 participants per 1000 with placebo (or no TXA) having a major surgical complication, this corresponds to 26 fewer (from 32 fewer to 16 fewer) participants with major surgical complications per 1000. Minor surgical complications - Systemic TXA may reduce minor surgical complications (RR 0.71, 95% CI 0.45 to 1.10; I2 = 76%; 5 studies, 733 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 396 participants per 1000 with placebo (or no TXA) having a minor surgical complication, this corresponds to 115 fewer (from 218 fewer to 40 more) participants with minor surgical complications per 1000. Unplanned hospitalizations or readmissions - We are very uncertain how unplanned hospitalizations or readmissions are affected (RR 1.55, 95% CI 0.45 to 5.31; I2 = not applicable; 1 study, 189 participants; very low CoE). We assumed an MCID of ≥ 2%. Hospital length of stay - Systemic TXA may reduce hospital LOS (mean difference 0.52 days lower, 95% CI 0.93 lower to 0.11 lower; I2 = 98%; 7 studies, 1151 participants; low CoE). We assumed an MCID of ≥ 0.5 days. AUTHORS' CONCLUSIONS: Based on 10 RCTs with substantial methodological limitations that lowered all CoE of effect, we found that systemic TXA in PCNL may reduce blood transfusions, major and minor surgical complications, and hospital LOS, as well as improve SFRs; however, it may increase AEs. We are uncertain about the effects of systemic TXA on other outcomes. Findings of this review should assist urologists and their patients in making informed decisions about the use of TXA in the setting of PCNL.

Beyond Prevalence: Annual Cumulative Incidence of Kidney Stones in the United States.

PURPOSE: It is well documented that the prevalence of nephrolithiasis is increasing in adults in the United States over time. Approximately 11% of men and 7% of women have reported a lifetime history of nephrolithiasis in cross-sectional studies. However, the burden of acute management may be better assessed from annual cumulative incidence. This accounting of new stone occurrences, however, is not well described on a national scale. MATERIALS AND METHODS: The Medical Expenditure Panel Survey is a set of large-scale health care utilization surveys of families, individuals, their health care providers and employers, with surveys administered every 6 months for the duration of each individual's 2-year panel. We queried the survey data of adult participants between 2005 and 2015, with analysis conducted with provided weights and strata to allow our findings to be representative of the civilian noninstitutionalized U.S. adult population. Those with diagnosed renal or ureteral calculi as noted by ICD-9 codes were included as our incident stone formers. RESULTS: In 2005, the mean age of stone formers was 45 years. Of stone formers 52.2% were male, 91% were White and 47.6% were in the Southern U.S. The incidence of stone occurrences was 0.6% (177/33,961 individuals, weighted to represent population of 1,923,322/296,185,002 individuals). By 2015, the mean age was 51.7 years, with 52% male, 83% White and 38.2% residing in the Southern U.S. Between 2005 and 2015, the overall incidence increased from 0.6% to 0.9% (p <0.001). CONCLUSIONS: Based on this large-scale, nationally representative analysis of adults in the United States, the estimated annual cumulative incidence of stone occurrence is approaching 1%. Moreover, this incidence appears to be increasing over time, rising from 0.6% in 2005 to 0.9% in 2015. These data may help to better anticipate the need for urological care for stone disease and direct resource distribution.

Risk of Symptomatic Kidney Stones During and After Pregnancy.

RATIONALE & OBJECTIVE: There are several well-known anatomical and physiological changes during pregnancy that could contribute to kidney stone formation, but evidence that they increase the risk of kidney stones during pregnancy is lacking. We determined whether there was an increased risk of a first-time symptomatic kidney stone during and after pregnancy. STUDY DESIGN: A population-based matched case-control study. SETTING & PARTICIPANTS: 945 female first-time symptomatic kidney stone formers aged 15-45 years and 1,890 age-matched female controls in Olmsted County, MN, from 1984-2012. The index date was the date of onset of a symptomatic kidney stone for both the case and her matched controls. EXPOSURE: The primary exposure was pregnancy with assessment for variation in risk across different time intervals before, during, and after pregnancy. Medical records were manually reviewed to determine the conception and delivery dates for pregnancies. OUTCOME: Medical record-validated first-time symptomatic kidney stone. ANALYTICAL APPROACH: Conditional and unconditional multivariable logistic regression analysis. RESULTS: Compared with nonpregnant women, the odds of a symptomatic kidney stone forming in women was similar in the first trimester (OR, 0.92; P=0.8), began to increase during the second trimester (OR, 2.00; P=0.007), further increased during the third trimester (OR, 2.69; P=0.001), peaked at 0 to 3 months after delivery (OR, 3.53; P<0.001), and returned to baseline by 1year after delivery. These associations persisted after adjustment for age and race or for diabetes mellitus, hypertension, and obesity. These results did not significantly differ by age, race, time period, or number of prior pregnancies. Having a prior pregnancy (delivery date>1year ago) was also associated with a first-time symptomatic kidney stone (OR, 1.27; P=0.01). LIMITATIONS: Observational study design in a predominantly White population. The exact timing of stone formation cannot be determined. CONCLUSIONS: Pregnancy increases the risk of a first-time symptomatic kidney stone. This risk peaks close to delivery and then improves by 1 year after delivery, though a modest risk of a kidney stone still exists beyond 1 year after delivery.

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.

Stent duration and increased pain in the hours after ureteral stent removal.

INTRODUCTION To assess the relationship between pain after ureteral stent removal and patient and procedural factors. MATERIALS AND METHODS: A validated survey designed to assess the relationship between quality of life and treatment decisions in kidney stone disease was randomly distributed to patients with a history of a ureteral stent in seven medical centers across North America participating in an endourology research collaborative between July 2016 and June 2018. The primary outcome was increased pain after ureteral stent removal. Statistical analyses were performed using Chi-square and multiple logistic regression. RESULTS: A total of 327 surveys were analyzed. Twenty seven percent of patients reported increased pain in the hours after ureteral stent removal. Patients with a stent ≤ 7 days were significantly more likely to experience pain after stent removal compared to those with a stent > 7 days (33.3% versus 22.8%, p = 0.04). Female gender (OR: 2.41, 95% CI: 1.42-4.10) was associated with increased pain after stent removal, while increasing age was inversely associated (OR: 0.52, 95% CI: 0.36-0.74). After adjustment, patients with a stent > 7 days were significantly less likely to report pain in the hours after removal (OR: 0.59, 95% CI: 0.35-0.99). CONCLUSIONS: Approximately one in four patients will experience increased pain after ureteral stent removal. Female patients, younger patients, and patients with a stent ≤ 7 days were more likely to experience an increase in pain immediately following stent removal. Understanding factors associated with post-stent removal pain may be helpful in counseling patients at high risk stent removal morbidity.

Kidney stones and the opioid epidemic: recent developments and review of the literature.

PURPOSE OF REVIEW: A public health emergency has been declared in response to rising opioid addiction and opioid-related deaths in the United States. As kidney stones have been identified as an important source of initial and repeated opioid exposures, this review seeks to describe the scope of the problem and report relevant alternatives to opioid analgesia for stones. RECENT FINDINGS: Recent literature summarizing the extent of opioid use among those with stones is reviewed. A number of opioid-minimizing strategies and analgesic regimens have been proposed and studied. A review of these modifications and alternatives is provided. SUMMARY: Both symptomatic renal colic and surgical interventions to address stones may prompt need for analgesia. Reducing prescribed opioids reduces both patient use and risk of diversion. Modifications in surgical technique, administration of local anesthetics, and use of systemic nonopioid analgesics have all been successfully employed.

The use of outpatient opioid medication for acute renal colic and ureteral stents: Insights from a multi-institutional patient survey
.

AIMS: To investigate the main reasons for use of opioids during acute episodes of renal colic and for ureteral stent symptoms post-operatively. MATERIAL AND METHODS: A survey assessing the impact of decreased quality of life and use of opioid pain medication was distributed to patients with a history of ureteral stent at seven academic centers between July 2016 and June 2018. RESULTS: A total of 365 surveys were completed. Opioid use for stone (63.9%) and stent-related pain (39.0%) was common among respondents. When assessing whether patients used more opioids for stone or stent-related pain, 47.7% reported using more for stone pain while 15.0% reported using more for stent pain. 22.6% of patients required opioids for stent-related pain and not stone pain. Increasing patient age was found to be negatively associated with using opioids for stent-related pain (OR: 0.4, 95% CI: 0.3 - 0.6). Increasing age was also found to be negatively associated with opioid use for stone pain (OR: 0.6, 95% CI: 0.4 - 0.8). Patients with a greater number of prior stones had 3.2 times the odds of using opioids for stone pain, in our adjusted model (95% CI: 2.1 - 4.7). CONCLUSION: Patients with more prior stone episodes are more likely to have used opioids for their most recent episode. Although ureteral stents have been shown to be associated with a decreased quality of life, we showed that the use of opioids for stent-related pain is less than that for stone pain. Younger patients are less likely to tolerate a stent without opioid analgesics.

Implications of Erdheim-Chester disease and percutaneous renal access.

Erdheim-Chester disease (ECD) is a rare systemic histiocytosis with urologic manifestations in a majority of affected patients. An important manifestation is a pronounced retroperitoneal fibrosis with reported dense inflammatory rind surrounding the kidneys. We report a case of a patient with large stone burden necessitating percutaneous nephrolithotomy and the implications related to his Erdheim-Chester-related retroperitoneal fibrotic changes. Foreknowledge of these implications may inform perioperative counseling and surgical planning to maximize opportunity for successful outcomes.

Understanding the relationship between health insurance and kidney stones: an examination of NHANES data.

INTRODUCTION: To investigate the relationship between socioeconomic factors, specifically insurance status, and kidney stones using a nationally representative cohort. MATERIALS AND METHODS: A retrospective secondary data analysis of National Health and Nutrition Examination Survey (NHANES) data from 2007 to 2014 was performed. Using univariate statistics and multiple logistic regressions, we examined the relationship between socioeconomic factors and kidney stone history. RESULTS: The weighted national prevalence of nephrolithiasis between ages 20 and 64 was 7.7% of a population of over 95.3 million. Fifty-three percent of the total population was female. The mean age was 42 years and the mean body mass index (BMI) was 28.7. The prevalence of nephrolithiasis was higher among individuals who had state-assisted insurance compared to those with private insurance (10.3% versus 7.3%, p = 0.005). On univariate regression analysis, having a college education was protective against stones compared to having less than a high-school degree (OR 0.62, 95% CI 0.43-0.84; p = 0.009). Income was also significantly associated with kidney stone prevalence. After adjusting for race, BMI, gender, water intake, income, and education level through multivariable analysis, having private insurance was associated with lower odds of developing nephrolithiasis compared to having state-assisted insurance (OR 0.62, 95% CI 0.44-0.89; p = 0.01). CONCLUSIONS: Individuals with state-assisted insurance were found to have significantly increased odds of a kidney stone compared to those with private insurance. Urologists, primary care, and policy makers should recognize this disparity exists and target opportunities to elucidate mechanisms and provide intervention for this high-risk group.

Symptomatic and Radiographic Manifestations of Kidney Stone Recurrence and Their Prediction by Risk Factors: A Prospective Cohort Study.

BACKGROUND: Meaningful interpretation of changes in radiographic kidney stone burden requires understanding how radiographic recurrence relates to symptomatic recurrence and how established risk factors predict these different manifestations of recurrence. METHODS: We recruited first-time symptomatic stone formers from the general community in Minnesota and Florida. Baseline and 5-year follow-up study visits included computed tomography scans, surveys, and medical record review. We noted symptomatic recurrence detected by clinical care (through chart review) or self-report, and radiographic recurrence of any new stone, stone growth, or stone passage (comparing baseline and follow-up scans). To assess the prediction of different manifestations of recurrence, we used the Recurrence of Kidney Stone (ROKS) score, which sums multiple baseline risk factors. RESULTS: Among 175 stone formers, 19% had symptomatic recurrence detected by clinical care and 25% detected by self-report; radiographic recurrence manifested as a new stone in 35%, stone growth in 24%, and stone passage in 27%. Among those with a baseline asymptomatic stone (54%), at 5 years, 51% had radiographic evidence of stone passage (accompanied by symptoms in only 52%). Imaging evidence of a new stone or stone passage more strongly associated with symptomatic recurrence detected by clinical care than by self-report. The ROKS score weakly predicted one manifestation-symptomatic recurrence resulting in clinical care (c-statistic, 0.63; 95% confidence interval, 0.52 to 0.73)-but strongly predicted any manifestation of symptomatic or radiographic recurrence (5-year rate, 67%; c-statistic, 0.79; 95% confidence interval, 0.72 to 0.86). CONCLUSIONS: Recurrence after the first stone episode is both more common and more predictable when all manifestations of recurrence (symptomatic and radiographic) are considered.

Association of Patient Age and Gender with Kidney Stone Related Quality of Life.

PURPOSE: Kidney stone formers have lower health related quality of life than nonstone formers. The North American Stone Quality of Life Consortium is a multicenter, longitudinal, prospective study of health related quality of life in patients with kidney stones using the WISQOL (Wisconsin Stone Quality of Life Questionnaire) with data on 2,052 patients from a total of 11 centers. This study is a subanalysis of cross-sectional data looking at the association of age, gender and race on health related quality of life of stone formers. MATERIALS AND METHODS: We performed multivariable analyses of ordinal logistic regression analyses to determine the impact of age, gender and race on health related quality of life, adjusting for other baseline covariates. The proportional odds assumption of ordinal logistic regression was checked. Total score and scores on 4 subdomains (social functioning, emotional functioning, stone related impact and vitality) were included. RESULTS: Median total score for all patients was 80.4. On multivariable analysis older patients had a significantly higher total health related quality of life score than younger patients (per 10-year increase OR 1.25, p <0.0001). Male patients had higher scores than females (OR 1.56, p = 0.0003) and nonCaucasian patients had lower health related quality of life than nonLatino Caucasian patients (OR 0.63, p = 0.0045). CONCLUSIONS: Younger and female patients with kidney stones have lower health related quality of life than older and male patients, respectively. NonCaucasian patients with stones also have lower health related quality of life. The clinical impact of these findings might include future implications for patient counseling, including dietary and medical management of stone disease, and potential changes to the paradigm of the surgical management of stones.

Low Income and Nonwhite Race are Strongly Associated with Worse Quality of Life in Patients with Nephrolithiasis.

PURPOSE: Kidney stones are a source of significant morbidity which have been shown to negatively impact health related quality of life. We sought to understand the association between health related quality of life, socioeconomic status and race among patients with kidney stones. MATERIALS AND METHODS: Patients with stones at a total of 11 stone centers across the United States completed the WISQOL (Wisconsin Stone Quality of Life questionnaire). The patient ZIP Code™ was used to estimate household income. A mixed effects regression model was constructed for analysis with ZIP Code as the random intercept. RESULTS: A total of 2,057 stone formers completed the WISQOL. Lower income was independently associated with significantly lower health related quality of life (ß = 0.372, p = 0.014), as were nonwhite race (ß = -0.299, p = 0.001), unemployed work status (ß = -0.291, p = 0.008), female gender (ß = -0.204, p <0.001), body mass index greater than 40 kg/m2 (ß = -0.380, p <0.001), 5 or more medical comorbidities (ß = -0.354, p = 0.001), severe recurrent stone formation (ß = -0.146, p = 0.045), enrollment at an acute care visit, or a preoperative or postoperative appointment (ß = -0.548, p <0.001) and recent stone symptoms (ß = -0.892, p <0.001). CONCLUSIONS: Lower income, nonwhite race and unemployed work status were independently associated with lower health related quality of life among patients with kidney stones. While clinical characteristics such as body mass and stone disease severity were also associated with health related quality of life, this study shows that socioeconomic factors are similarly important. Further research to understand the specific mechanisms by which socioeconomic status and race impact health may lend insight into methods to optimize clinical treatment of stone formers and patients with other chronic diseases.

Leave no stone unturned: defining recurrence in kidney stone formers.

PURPOSE OF REVIEW: Established guidelines provide recommendations on the management of kidney stones to prevent recurrence. However, clear and clinically useful terminology for recurrence of kidney stones is needed. This review describes the various manifestations of kidney stone recurrence and the reported rates of kidney stone recurrence in various clinical settings. RECENT FINDINGS: Kidney stone recurrence has a wide range of symptomatic and radiographic presentations. Symptomatic recurrence may include characteristic symptoms of stone passage via the ureter (renal colic and gross hematuria). This may be self-managed or result in clinical care, with or without confirmation of an obstructing stone on imaging. Radiographic recurrence has been variably defined as new stone formation, stone growth, or stone disappearance (from passage with or without symptoms). Studies have used inconsistent definitions of recurrence, and recurrence rates vary substantially. Stone free rates and residual stone fragment size after surgical interventions are useful predictors of symptomatic recurrence. SUMMARY: The recurrence rate of kidney stones has been assessed in stone formers from sub-specialty clinics, the general community, and clinical trials. The definition of recurrence is quite heterogenous between studies, but the rate of recurrence generally increases as more manifestations are included in the definition.

The association of nephrolithiasis with prescription opioid use
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OBJECTIVE: To characterize opioid utilization among those with nephrolithiasis in a national cohort. MATERIALS AND METHODS: We performed cross sectional analysis of participants in the Medical Expenditure Panel Surveys during 2008 - 2014. Sample weights were employed for analysis of complex survey design. Those reporting occurrence of "renal or ureteral calculus" during the survey period represented the cohort of stone formers (SFs). Receipt of opioid prescription as well as total number of opioid prescriptions filled over study period were noted. RESULTS: Of 65,397 adult participants - weighted to represent 209,043,539 - 1.29% reported occurrence of nephrolithiasis. SFs were older, had higher BMI, and higher likelihood of depression and anxiety. Compared with those without nephrolithiasis, SFs had higher prevalence of opioid use (59.5 vs. 20.2%, p < 0.0001). On multivariate analysis, the odds of receiving an opioid prescription were increased greater than 5 times in SFs compared with those without stones (OR 5.61, 95% CI 4.59 - 6.85). Assessing each individual's total number of opioid prescriptions revealed SFs had a greater mean number of opioid prescriptions filled than those without nephrolithiasis (2.53 vs. 0.97, p < 0.001). Among SFs receiving opioids, depression and anxiety were both associated with a significantly greater number of opioid prescriptions (6.80 vs. 3.66, p < 0.001; and 8.91 vs. 3.38, p = 0.008, respectively). CONCLUSION: A majority of those with renal stone occurrence receive prescription opioids. Of particular note, the presence of either depression or anxiety is associated with larger total number of opioid prescriptions over the study period.
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Gender Equivalence in the Prevalence of Nephrolithiasis among Adults Younger than 50 Years in the United States.

PURPOSE: Although urolithiasis affects each gender, conventional teaching proposes that men are 3 times more likely to have stones. However, clinical practice refutes such a disparity, particularly among working age adults. Small studies have suggested an erosion of this gender gap. Therefore, we examined the relationship between gender and stone prevalence among American adults younger than 50 years. MATERIALS AND METHODS: We analyzed the NHANES (National Health and Nutrition Examination Survey) 2007 to 2012 cohort. Weighted proportions and multivariate logistic regression of the cohort and pertinent subgroups were assessed to determine the prevalence and the odds of nephrolithiasis. RESULTS: The cohort of 17,658 subjects, which was weighted to represent the American population of 218,828,951 adults, was 48.1% male. In our cohort of 8,888 adults weighted to represent 123,976,786 subjects younger than 50 years, which was 49.3% male and 50.7% female, there was no difference in stone prevalence (6.3% in males and 6.4% in females, p = 0.85). On unadjusted logistic regression of those younger than 50 years men were no more likely to report a stone history (OR 0.98, p = 0.85). Multivariate logistic regression adjusting for diabetes, obesity, ethnicity, age, and water, sodium and protein intake confirmed no difference in stone prevalence between the genders (OR 1.1, p = 0.51). CONCLUSIONS: Among adults of working and child rearing ages in the United States the much touted gender disparity in nephrolithiasis is not present. Prior assessments of gender based stone prevalence may have failed to specifically assess this economically critical demographic or there may in fact be an ongoing epidemiological change. Recognition that women are as likely as men to form stones in this cohort suggests the need to better elucidate the pathophysiology of stones in women.