Economics and cost of care of stone disease

Clinical, Diagnostic, and Metabolic Characteristics Associated with Nephrolithiasis in the Black Women's Health Study

Background/Objectives: Nephrolithiasis (kidney stones) is a frequently occurring urologic condition resulting in significant patient morbidity and healthcare costs. Despite the higher prevalence of metabolic risk factors for nephrolithiasis among Black women, there have been few epidemiologic studies of kidney stones focusing on this group. Methods: We describe demographic and health characteristics, diagnostics, and metabolic profiles of US Black women with self-reported kidney stones. The women were participants in the Black Women's Health Study (BWHS), a large prospective cohort of US Black women (median age 38 years) begun in 1995. Results: Among the 2750 BWHS participants who completed an online supplemental questionnaire assessing urologic health, 201 women reported nephrolithiasis. Of this number, 62% had completed ≥ 16 years of education, and 82% reported access to health care. Overall, 39% reported experiencing ≥ 2 stones in their lifetime, and 29% required surgery to treat the condition. Thirty-two percent reported having completed a metabolic evaluation, while 70% had undergone a CT scan to diagnose nephrolithiasis. The frequency of metabolic evaluation increased with the number of metabolic components reported: 3% (0 components) to 43% (3-4 components). Conclusions: Our findings are consistent with reports of lower rates of metabolic evaluation among Black patients despite their having multiple risk factors for nephrolithiasis. Further study is needed to identify the barriers and facilitators of metabolic and diagnostic workup of nephrolithiasis in Black women.

Blood Calcium, Genetic Risk, and Risk of Incident Kidney Stone: A Population-Based Cohort Study

OBJECTIVE

To investigate the association between blood calcium concentration and incident kidney stone as well as to assess the role played by genetic susceptibility.

METHODS

We performed a population-based cohort study based on participants from the UK Biobank. A multivariable Cox proportional hazards regression model was used to estimate hazard ratios (HRs) and 95% CIs of incident kidney stone for blood calcium level and polygenic risk score (PRS). In addition, the potential interaction was explored. The study was conducted from January 28, 2023, through June 4, 2023.

RESULTS

During the follow-up of 423,301 participants with a total of 5,490,332 person-years (median follow-up of 13.4 years), 4502 cases of kidney stone were recorded. Compared with the low blood calcium concentration group (first tertile), individuals in the high (third tertile) and moderate (second tertile) concentration groups had higher risks of kidney stone with HRs of 1.24 (95% CI, 1.15 to 1.33) and 1.11 (1.04 to 1.20), respectively. The PRS for kidney stone contained 40 independent single-nucleotide polymorphisms and was used to assign individuals to 3 groups according to the quintile. Participants with high (Q5) and moderate (Q2 to Q4) genetic risks had increased risks of kidney stone compared with low (Q1) genetic risk with HRs of 1.70 (1.53 to 1.89) and 1.31 (1.20 to 1.44), respectively. There was a joint cumulative risk of incident kidney stone between blood calcium concentration and genetic susceptibility.

CONCLUSIONS

Blood calcium concentration and PRS are significantly associated with incident kidney stone risk. Excessive blood calcium concentration might bring additional stone risk in populations at high genetic risk. A nonlinear correlation between blood calcium concentration and kidney stone risk was indicated.

Exploring the economic landscape of ureteric stones: impact of age and gender on direct healthcare costs

OBJECTIVES

To assess whether age or gender affects ureteric stone management costs, in patients presenting to the Emergency Department (ED) with CT proven ureteric stones.

PATIENTS AND METHODS

A retrospective examination was conducted on patients admitted to the ED who were diagnosed with a ureteric stone through CT scans. Data encompassing clinical, laboratory, and imaging parameters were gathered, alongside information on admissions, ED readmissions, surgical procedures, and the overall treatment cost. Comparative analyses were performed on various cost rates in relation to different stone parameters, patient clinical presentations, laboratory results, and personal histories of urolithiasis.

RESULTS

From January 2018 to January 2020, 805 patients underwent abdominal CT scans at a single institution's ED and were diagnosed with ureteric stones. Among them, 773 patients met the inclusion criteria, with 78% (609) being males and 22% (169) females. The mean ages for males and females were 49.4 (SD 14.4) and 51.6 (SD 15.7), respectively (p = 0.08). Treatment costs exhibited a direct relationship with age, amounting to 4,025, 5,116, 6,058, and 9,225 US dollars (USD) in the 18-30, 31-50, 51-70, and over 70 age groups, respectively. Female gender was associated with higher treatment costs, averaging 6,831 USD, compared to 5,450 USD in males (p = 0.03). However, there were no significant differences between genders in terms of the type of surgical procedure (p = 0.4) or hospital stay duration (p = 0.1).

CONCLUSIONS

Age and gender exerted a significant impact on treatment costs, revealing that advanced age and female gender were both correlated with higher direct treatment costs in the care of ureteric stones.

Proton pump inhibitors use is associated with a higher prevalence of kidney stones: NHANES 2007-2018

BACKGROUND

Proton pump inhibitors (PPIs) are widely used throughout the world as an effective gastrointestinal drug. Nevertheless, according to the existing literature, PPIs can reduce the excretion of magnesium, calcium and other components in urine, which may promote the formation of kidney stones. We used the National Health and Nutrition Examination Survey (NHANES) database to further investigate the association between the use of PPIs and the prevalence of kidney stones.

METHODS

We performed a cross-sectional analysis using data from 2007 to 2018 NHANES. PPIs use information of 29,910 participants was obtained by using prescription medications in the preceding month, and kidney stones were presented by a standard questionnaire. Multiple regression analysis and stratified analysis were used to estimate the association between PPIs use and kidney stones after an adjustment for potential confounders.

RESULTS

The multiple logistic regression indicated that the PPIs exposure group (P1) had a significantly higher risk of nephrolithiasis than the PPIs non-exposure group (P0) in Model 3 (OR 1.24, 95% CI 1.10-1.39, P < 0.001). The stratified analyses indicated there were significant statistical differences between PPIs use and kidney stones among females (OR 1.36, 95% CI 1.15-1.62, P < 0.001), non-Hispanic whites (OR 1.27, 95% CI 1.09-1.48, P = 0.002), individuals with an education level than 11th grade (OR 1.41, 95% CI 1.13-1.76, P = 0.002) and individuals with an annual family income of $0 to $19,999 (OR 1.32, 95% CI 1.06-1.65, P = 0.014) and $20,000 to $44,999 (OR 1.25, 95% CI 1.02-1.54, P = 0.033) in Model 3.

CONCLUSIONS

Our study revealed that PPIs use is associated with a higher prevalence of kidney stones for the US population, primarily among women, non-Hispanic whites, individuals with low education levels and individuals with low household income levels. Further studies are required to confirm our findings.

The Analgesic Effects of the Thoracic Paravertebral Block on Post-percutaneous Nephrolithotripsy: A Retrospective Study

INTRODUCTION

Percutaneous nephrolithotripsy (PCNL) is a minimally invasive procedure for treating large and complex kidney stones, often resulting in significant post-operative pain and increased opioid use. This study aims to compare pain scores between patients undergoing PCNL who did and did not receive a preoperative single-shot thoracic paravertebral block (PVB) at the post-anesthesia care unit (PACU) as the primary outcome. Secondary outcomes were patient-controlled analgesia (PCA) usage on post-operative day 1 (POD 1), total opioid consumption on PACU and POD 1, and post-operative nausea and vomiting (PONV).

METHODS

A retrospective cohort study was conducted on the medical records of 341 patients who underwent PCNL from July 2014 to April 2016 in a single major academic center. PVB was administered at thoracic levels T7-9 using a volume of 20 cc of bupivacaine, ranging from 0.25% to 0.5%, to achieve the desired analgesic effect.

RESULTS

After excluding 34 patients, the study included 123 in the no block (NB) group and 149 in the regional anesthesia (RA) group. There were no differences in demographics, including age, sex, weight and height, BMI, and indication for PCNL. The results revealed that the RA group experienced a statistically significant reduction in PCA usage in both crude and adjusted models (adjusted logistic regression analysis: OR = 0.19, 95% CI = 0.05-0.60; p = 0.008). However, there were no significant changes in total opioid consumption, pain scores, or incidents of PONV.

CONCLUSION

The retrospective analysis did not reveal any discernible advantage in pain management associated with the use of PVB for post-PCNL analgesia, except for reducing the percentage of PCA narcotics used. Future investigations with larger sample sizes and meticulous control for surgical indications and complexity are imperative to accurately assess the efficacy of this block in the context of post-PCNL surgery.

Effects of Klotho protein, vitamin D, and oxidative stress parameters on urinary stone formation and recurrence

PURPOSE

The present study aimed to investigate the effects of α-Klotho and oxidative stress markers on urinary stone disease (USD) and demonstrate their use as biochemical markers in USD.

METHODS

Among the 90 individuals included, 30 individuals were healthy controls (Group 1), 30 individuals presented with USD for the first time (Group 2), and 30 individuals demonstrated recurrent USD (Group 3). Serum levels of α-Klotho, vitamin D, malondialdehyde (MDA), total oxidant status, and total antioxidant status were determined using spectrophotometry analysis. Serum calcium and parathormone levels and 24-h urine calcium levels were measured via biochemical analysis.

RESULTS

No significant intergroup difference was noted in terms of age and sex. The groups had significant differences regarding α-Klotho, oxidative stress index (OSI), MDA, and 24-h urine calcium levels. α-Klotho was a determinant of 24-h urine calcium level and OSI. An increase of 1 pg/mL in α-Klotho level appeared to result in a decrease of 8.55 mg in 24-h urine calcium level and a decrease of 0.04 Arbitrary Unit in OSI. In patients experiencing USD for the first time, α-Klotho values were < 21.83 pg/mL and showed 66% sensitivity and 64% specificity. In individuals with recurrent stone formation, α-Klotho values below 19.41 pg/mL had 60% sensitivity and 77% specificity.

CONCLUSIONS

The biochemical markers investigated herein, i.e., α-Klotho, OSI, and MDA, were involved in the pathogenesis of stone formation and can be used in day-to-day clinical practices of urology clinics to identify patients at risk for both first time and recurrent USD.

Gaps in kidney stone disease management: From clinical theory to patient reality

With nephrolithiasis projected to affect 25% of the global population in the next three decades, there is an urgent call for innovative management strategies to prevent and reduce stone recurrence. This study aims to explore the evolving management needs in nephrolithiasis from both patient and healthcare provider perspectives. An expert-collaborative online survey comprising 10 targeted questions on kidney stone management was developed and disseminated. This survey was designed to gather comprehensive insights from patients, physicians and dietician and other person in the field of nephrolithiasis. Analysis of responses from 120 participants, including 45 nephrologists, 38 dieticians, 11 urologists, and 14 kidney stones patients followed in our hospital, revealed critical insights. A significant 97.5% emphasized the necessity of optimizing daily water intake, and 94.1% recognized the need for practical dietary modifications. Additionally, 88.3% of respondents found timely hydration reminders beneficial. Notably, monitoring urine color and pH was valued by 85% and 84.3% of the participants, respectively. A striking disparity emerged in the perception of fatigue and wellness monitoring, with 65% of patients prioritizing fatigue monitoring, a view less shared by healthcare professionals. Similarly, 71% of patients deemed wellness monitoring essential, highlighting a gap in understanding between patients and their caregivers. This study underscores the critical need for more tailored guidance on hydration strategies and the promise of remote urine parameters monitoring in nephrolithiasis management. The findings strongly advocate for a patient-centered approach, aligning medical recommendations with patient lifestyles and experiences, to enhance the effectiveness of nephrolithiasis management.

PCNL vs. two staged RIRS for kidney stones greater than 20 mm: systematic review, meta-analysis, and trial sequential analysis

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is considered the gold standard treatment for kidney stones greater than 20 mm. However, retrograde intrarenal surgery (RIRS) may achieve the same stone-free rate with repeated procedures, and potentially fewer complications. This study aimed to compare the efficacy and safety of PCNL and two-staged RIRS.

EVIDENCE ACQUISITION

We conducted a systematic search in PubMed, Embase, Scopus, Cochrane, and Web of Science for studies comparing PCNL and RIRS for kidney stones greater than 20mm. The primary outcome is stone-free rate (SFR) of PCNL and RIRS (repeated once if needed). Secondary outcomes were SFR of PCNL versus RIRS (single procedure), operative time, hospital stay, need for auxiliary procedures, and complications. We performed a subgroup analysis for randomized trials, non-randomized trials, and patients with solitary kidney. We performed a trial sequential analysis for the main outcome.

EVIDENCE SYNTHESIS

We included 31 articles, with 1987 patients in the PCNL and 1724 patients in RIRS. We confirmed the traditional result that after a single procedure PCNL has a higher SFR. We also found that comparing the SFR of PCNL and RIRS, repeated up to two times if needed, no difference in SFR was observed. Surprisingly, only 26% (CI95 23%-28%) of the patients required a second RIRS. In the trial sequential analysis, the last point of the z-curve was within futility borders. We observed that PCNL has a higher incidence of complications (RR=1.51; CI95 1.24, 1.83; P<0.0001; I2=28%), specifically CD2 (RR=1.82; CI95 1.30, 2.54; P=0.0004; I2=26%) and longer hospital stay (MD 2.57; 2.18, 2.96; P<0.00001; I2-98%). No difference was observed regarding operative time.

CONCLUSIONS

RIRS repeated up to two times is equivalent to PCNL in terms of the SFR and may have the same safety.

Association of Chronic Hyperglycemia With the Risk of Urolithiasis

Background The incidence of urolithiasis is increasing along with elevated rates of chronic hyperglycemia. Therefore, this study aimed to assess the association between high hemoglobin Alc (HbAlc) levels, in the form of type 2 diabetes mellitus (T2DM), and the risk of kidney stone formation among those living in the Eastern Province of Saudi Arabia. Methodology We conducted a cross-sectional study on a total of 501 patients with known cases of urolithiasis who visited King Fahad University Hospital (Khabar, Saudi Arabia). We calculated odds ratios (ORs) of having stones with respect to three parameters, namely, fasting blood glucose level, random blood glucose level, and glycosylated HbA1c testing. Results Of the 501 cases with urinary stones included in this study, the majority (223, 44.5%) were 41-59 years of age, and 350 (69.9%) were males. Our results showed that T2DM was significantly associated with high stone burden, with increased fasting plasma glucose, increased random blood glucose, and increased HbA1c being strong predictors. The significant associations between glycemic control measures and the risk of urolithiasis remained even after adjusting for factors related to insulin resistance. Conclusions According to our results, glycemic control can be an independent risk factor for urolithiasis. This critical finding demonstrates the need for further studies to investigate this particular group of patients.

Evaluation of risk factors for recurrent renal stone formation among Saudi Arabian patients: Comparison with first renal stone episode

OBJECTIVES

We evaluated the baseline characteristics, and risk factors of renal stone recurrence among Saudi Arabian patients after successful primary stone treatment.

MATERIALS AND METHODS

In this cross-sectional comparative study, we reviewed the medical records of patients who presented consecutively with a first renal stone episode from 2015 to 2021 and were followed-up by mail questionnaire, telephone interviews, and/or outpatient clinic visit. We included patients who achieved stone-free status after primary treatment. Patients were divided into two groups: group I (patients with first episode renal stone) and group Ⅱ (patients who developed renal stone recurrence). The study outcomes were to compare the demographics of both groups and to evaluate the risk factors of renal stone recurrence after successful primary treatment. We used Student's t-test, Mann Whitney test or chi-square (x2) to compare variables between groups. Cox regression analyses were used to examine the predictors.

RESULTS

We investigated 1260 participants (820 males and 440 females). Of this number, 877 (69.6%) didn't develop renal stone recurrence and 383 (30.4%) had recurrence. Primary treatments were percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery (RIRS), extracorporeal shock wave lithotripsy (ESWL), surgery and medical treatment in 22.5%, 34.7%, 26.5%, 10.3%, and 6%, respectively. After primary treatment, 970 (77%) and 1011 (80.2%) of patients didn't have either stone chemical analysis or metabolic work-up, respectively. Multivariate logistic regression analysis revealed that male gender (OR: 1.686; 95% CI, 1.216-2.337), hypertension (OR: 2.342; 95% CI, 1.439-3.812), primary hyperparathyroidism (OR: 2.806; 95% CI, 1.510-5.215), low fluid intake (OR: 28.398; 95% CI, 18.158-44.403) and high daily protein intake (OR: 10.058; 95% CI, 6.400-15.807) were predictors of renal stone recurrence.

CONCLUSIONS

Male gender, hypertension, primary hyperparathyroidism, low fluid intake and high daily protein intake increase the risk of renal stone recurrence among Saudi Arabian patients.

The effectiveness of citrates and pyridoxine in the treatment of kidney stones

The prevalence of nephrolithiasis is increasing across all demographic groups. Apart from the morbidity associated with an acute occurrence, preventative treatment is essential for stone disease, which can become a long-term problem. Simple interventions like fluid intake optimization and dietary modification are effective for most stone types. However, patients with specific metabolic abnormalities may require pharmaceutical therapy if lifestyle changes are insufficient to reduce the risk of stone recurrence. The treatment of citrates and/or pyridoxines may help eliminate or prevent recurrences of kidney stones, especially when they are composed of uric acid, calcium oxalate, calcium phosphate, or the latter two together. In cases of struvite stones, which often necessitate a surgical approach, acetohydroxamic acid emerges as a valuable second-line treatment option. Thiol-binding agents may be needed for cystinuria, as well as lifestyle modifications. Successful treatment reduces stone recurrence and the need to remove stones surgically.

Determinants of renal papillary appearance in kidney stone formers: An in-depth examination

OBJECTIVES

The aim of this study is to investi-gate the association between the urinary metabolic milieu and kidney stone recurrence with a validated papillary evaluation score (PPLA).

MATERIALS AND METHODS

We prospectively enrolled 30 stone for-mers who underwent retrograde intrarenal surgery procedures. Visual inspection of the accessible renal papillae was performed to calculate PPLA score, based on the characterization of ductal plugging, surface pitting, loss of papillary contour and Randall's plaque extension. Stone compositions, 24h urine collections and kidney stone events during follow-up were collected. Relative supersaturation ratios (RSS) for calcium oxalate (CaOx), brushite and uric acid were calculated using EQUIL-2. PPLA score > 3 was defined as high.

RESULTS

Median follow-up period was 11 months (5, 34). PPLA score was inversely correlated with BMI (OR 0.59, 95% CI 0.38, 0.91, p = 0.018), type 2 diabetes (OR 0.04, 95% CI 0.003, 0.58, p = 0.018) and history of recurrent kidney stones (OR 0.17, 95%CI 0.04, 0.75, p = 0.019). The associations between PPLA score, diabetes and BMI were not confirmed after excluding patients with uric acid stones. Higher PPLA score was associated with lower odds of new kidney stone events during follow-up (OR 0.15, 95% CI 0.02, 1.00, p = 0.05). No other significant correla-tions were found.

CONCLUSIONS

Our results confirm the lack of efficacy of PPLA score in phenotyping patients affected by kidney stone disease or in predicting the risk of stone recurrence. Larger, long-term studies need to be performed to clarify the role of PPLA on the risk of stone recurrence.

Correlates of nephrolithiasis in US black women: data from the black women's health study

Nephrolithiasis is a common urologic condition and a significant source of patient morbidity and healthcare expenditure. There are few epidemiologic studies of kidney stones focusing exclusively on Black women. We retrospectively assessed the prevalence and correlates of self-reported kidney stones within the Black Women's Health Study (BWHS). Descriptive statistics and multivariable logistic regression models were used to explore factors associated with nephrolithiasis. As of the 2005 follow-up questionnaire, a cumulative total of 1063 women among 43,178 reported ever being diagnosed with kidney stones for a prevalence of 2.64%. Women with a history of nephrolithiasis were older, slightly heavier, and were more likely to have a comorbid condition (e.g., type-2 diabetes, gallstones), drink alcohol, and consume a Western-style diet. A history of gallstone disease was associated with an odds ratio (OR) of 3.59 (95% confidence interval (CI) 3.09-4.17). The OR for consuming ≥ 7 alcoholic beverages/week, compared to none was 0.61 (0.39-0.94), while the OR for high adherence to the Western diet, compared to low adherence was 1.53 (1.23-1.90). Our findings are consistent with previous studies of primarily white populations relating lifestyle-associated risk factors with nephrolithiasis. Despite their lower prevalence of kidney stones, it is important to focus on vulnerable populations such as Black women given their disproportionate burden of metabolic conditions (e.g., obesity, diabetes) related to kidney stone disease.

Dietary selenium intake and the risk of kidney stones in adults, an analysis of 2007-2018 National Health and Nutrition Examination Survey, a cross-sectional study

Purpose

To evaluate the association between dietary selenium intake and the risk of kidney stones in adults.

Materials and methods

We performed a cross-sectional analysis using data from 2007 to 2018 National Health and Nutrition Examination Survey (NHANES). Dietary intake information of 30,184 participants was obtained using first 24-h dietary recall interview, and kidney stones were presented by a standard questionnaire. The quartile analysis, stratified analysis and non-linearity analysis were used to estimate the association between dietary selenium intake and kidney stones after an adjustment for potential confounders.

Results

The multiple logistic regression indicated that the fourth quantile (Q4) of dietary selenium intake had a lower risk of kidney stones than the first quantile (Q1) in Model 3 (OR 0.82, P < 0.05). The stratified analyses indicated there were statistical differences between dietary selenium intake and kidney stones among younger (age < 50) (OR 0.65, P < 0.01), male (OR 0.73, P < 0.01) and overweight/obese (BMI ≥ 25.0) (OR 0.80, P < 0.05) individuals in Model 3. The non-linear relationship was founded between dietary selenium intake and kidney stones in all participants, younger, male and overweight/obese individuals after adjusting for confounding factors.

Conclusion

Our study revealed an inverse relation between the level of dietary selenium intake and the risk of kidney stones for the United States population, especially for younger (age < 50), male and overweight/obese (BMI ≥ 25.0) individuals. The study provides preliminary guidance on dietary selenium intake for the prevention of kidney stones in different populations. Further studies are required to confirm our findings and clarified the biological mechanisms.

The role of inflammatory serum markers and ureteral wall thickness on spontaneous passage of ureteral stone < 10 mm: A prospective cohort study

Introduction

Ureteral stone is a worldwide disease and accounts for 20% of all urolithiasis. There is a widespread discussion on the preferred initial treatment method, whether medical or surgical, and each has its pros and cons. In this study, we aimed to assess the role of both ureteral wall thickness around the stone and inflammatory markers in guiding the decision-making process.

Methods

In this prospective study, 161 patients who presented with ureteric colic and were diagnosed with ureteral stone with NCCT were included. UWT around the stone was measured, and the NLR and PLR were calculated. The patients were given a single daily dose of tamsulosin 0.4 mg for 4 weeks with weekly follow-up to determine SSP or failure.

Results

Of the 161 patients with a mean age 40.12 ± 12.36 SD, 55.9% had a spontaneous stone passage. Receiver operating characteristics showed a cut off value of 2.45 mm UWT of non SSP patients with an 83% sensitivity and 86% specificity. Moreover, there was a significant correlation between higher NLR, PLR and increased UWT (Pearson correlation of 0.314 and 0.426 respectively). The combined higher NLR, PLR and increased UWT were associated with failure of SSP (p-value <0.001).

Conclusion

Many factors play a role in decision making for management of ureteral stones. Our study concludes that patients with high NLR, PLR, and UWT around the stone have lesser chance of SSP using MET. Their rise can be used as predictors to decide early intervention.

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Ureteral stone is a worldwide disease and accounts for 20% of all urolithiasis.

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Impacted ureteral stones occupy the majority of emergency department visits due to urolithiasis.

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The role of inflammatory serum markers and UWT around the stone on spontaneous passage are controversial.

Mutations in CLDN2 Are Not a Common Cause of Pediatric Idiopathic Hypercalciuria in Canada

Background:

Hypercalciuria is the most common risk factor for kidney stone formation, including in pediatric patients. However, the etiology is often unknown and children are frequently diagnosed with idiopathic hypercalciuria. Nearly 50% of children with hypercalciuria have a first-degree relative with kidney stones, suggesting a strong genetic basis for this disease. A failure of calcium reabsorption from the proximal nephron is implicated in the pathogenesis of hypercalciuria. Claudin-2 is a tight junction protein abundantly expressed in the proximal tubule. It confers paracellular permeability to calcium that is essential for transport across the proximal tubule where the majority of filtered calcium is reabsorbed.

Objective:

Our objective was to examine the frequency of coding variations in CLDN2 in a cohort of children with idiopathic hypercalciuria.

Design:

Mixed method including retrospective chart review and patient interview, followed by genetic sequencing.

Setting:

Three tertiary care centers in Canada.

Patients:

Children (age 1-18 years) with idiopathic hypercalciuria. Patients with other causes of hypercalciuria were excluded.

Methods:

Data were collected from 40 patients with idiopathic hypercalciuria. Informed consent to collect DNA was obtained from 13 patients, and the final and only coding exon of CLDN2 was sequenced.

Results:

The majority of patients were male, white, and had a positive family history of kidney stones. Parathyroid hormone levels were significantly lower than the reference range (P < .001). The levels of 1,25-dihydroxyvitamin D were also significantly higher in our patient cohort, relative to the reference range (P < .001). Sequence analysis of CLDN2 did not identify any coding variations.

Limitations:

Sequencing analysis was limited to the final coding exon and small sample size.

Conclusions:

CLDN2 coding variations are not a common cause of idiopathic hypercalciuria in Canadian children. Further study is needed to determine the causes of hypercalciuria in pediatric patients and develop targeted therapies.

Betel Nut Chewing Is Associated with the Risk of Kidney Stone Disease

(1) Background: Betel nut chewing injures bodily health. Although, the relationship between betel nut chewing and kidney stone disease (KSD) is unknown. (2) Methods: We analyzed 43,636 men from Taiwan Biobank. We divided them into two groups on the status of betel nut chewing, the never-chewer and ever-chewer groups. Self-reported diagnosed KSD was defined as the subject’s medical history of KSD in the questionnaire. Logistic regression was used to analyze the association of betel nut chewing and the risk of KSD. (3) Results: The mean age of subjects in the present study was 50 years, and 16% were ever-chewers. KSD was observed in 3759 (10.3%) and 894 (12.6%) participants in the group of never-chewer and ever-chewer groups, respectively. Higher risk of KSD was found in participants with betel nut chewing compared with to without betel nut chewing (odds ratio (OR), 1.094; 95% confidence interval (95% CI), 1.001 to 1.196). Furthermore, the daily amounts of betel nut chewing >30 quids was associated with a more than 1.5-fold increase (OR, 1.571; 95% CI, 1.186 to 2.079) in the odds of KSD; (4) Conclusions: Our study suggests that betel nut chewing is associated with the risk of KSD and warrants further attention to this problem.

The Relationship Between Renal Stones and Primary Aldosteronism

INTRODUCTION

The association between primary aldosteronism (PA) and nephrolithiasis is still unclear. The hypercalciuria and hypocitraturia of PA patients might be the reason leading to recurrent calcium nephrolithiasis. This study aimed to evaluate the relationship between PA and renal stones, including stone size and density.

MATERIALS AND METHODS

From February 2010 to March 2021, we retrospectively collected 610 patients who presented to our medical center with hypertension history, and all these patients, suspicious of PA, had PA data survey. In total, 147 patients had kidney stone and were divided into 44 patients with essential hypertension as group 1 and 103 patients with PA as group 2. Pearson χ² test and independent Student's t-test were performed to examine the differences among variables.

RESULTS

The mean age was 54.4 ± 12.0 years in group 1 and 53.0 ± 11.1 years in group 2. The incidence rate of renal stones in the PA group was around 24%. No significant differences between the two groups were found for gender, systolic/diastolic blood pressure, duration of hypertension, diabetes mellitus history, and laterality of kidney stone; however, mean stone size was 4.0 ± 3.3 mm in group 1 and 6.5 ± 7.2 mm in group 2, with a significantly larger renal stone size noted in the PA group than that in the essential hypertension group (p = 0.004). Hounsfield unit (HU) density was higher in the PA group vis-à-vis the essential hypertension cohort, although this did not reach a significant difference (p = 0.204).

CONCLUSIONS

Our study revealed that PA patients had a higher incidence rate of renal stones compared to that of the general population. Besides, the PA-related renal stones also presented as larger and harder than those of the essential hypertension group. Further investigation concerning the association between PA and renal stones is warranted.

Contemporary Assessment of the Economic Burden of Upper Urinary Tract Stone Disease in the United States: Analysis of 1-year Healthcare Costs, 2011-2018

Background The United States healthcare landscape has witnessed numerous changes since implementation of the Affordable Care Act coupled with rising prevalence of upper urinary tract stone disease. Data on the economic burden of stone disease during this period are lacking, providing the objective of our study. Materials and Methods Adults diagnosed with stone disease from 2011-2018 were identified from PearlDiver Mariner, a national all-payer database reporting reimbursements and prescription costs for all healthcare encounters. Patients undergoing operative and non-operative care were identified. Time trends in annual expenditures were evaluated. Multivariable analysis evaluated determinants of spending. Results A total of $10B were spent on stone disease management between 2011-2018 (median overall annual expenditure=$1.4B) among 786,756 patients. Inpatient, prescription and outpatient costs accounted for 34.7%, 20.7% and 44.6% of expenditures respectively. 78% of patients were managed non-operatively (total cost=$6.9B). Average overall cost per encounter was $13,587 ($17,102 for surgical vs. $11,174 for non-surgical care). Expenditures on inpatient care decreased significantly over time, while expenditures on prescriptions and outpatient care increased significantly. On multivariable analysis, higher Charlson Comorbidity Index was associated with higher spending, while associations for age, insurance and region varied by treatment modality. Conclusions The economic burden of stone disease management is substantial, dominated by expenditure on non-operative management and outpatient care. Expenditures for prescription and outpatient care are rising, with the only consistent predictor of higher spending being Charlson Comorbidity Index. Spending variation according to demographic, clinical, and geographic factors was evident.

Preliminary assessment of a portable Raman spectroscopy system for post-operative urinary stone analysis

PURPOSE

We aimed to evaluate the reliability of a portable device that applies Raman spectroscopy at an excitation wavelength of 1064 nm for the post-operative analysis of urinary stone composition.

MATERIALS AND METHODS

Urinary stone samples were obtained post-operatively from 300 patients. All samples were analyzed by the portable Raman spectroscopy system at an excitation wavelength of 1064 nm as well as by infrared spectroscopy (IR), and the results were compared.

RESULTS

Both Raman spectroscopy and IR could detect multiple stone components, including calcium oxalate monohydrate, calcium oxalate dihydrate, calcium phosphate, uric acid, cystine, and magnesium ammonium phosphate hexahydrate. The results from 1064-nm Raman analysis matched those from IR analysis for 96.0% (288/300) of cases. Although IR detected multiple components within samples more often than Raman analysis (239 vs 131), the Raman analysis required less time to complete than IR data acquisition (5 min vs 30 min).

CONCLUSIONS

These preliminary results indicate that 1064-nm Raman spectroscopy can be applied in a portable and automated analytical system for rapid detection of urinary stone composition in the post-operative clinical setting.

TRIAL REGISTRATION

Chinese Clinical Trail Register ID: ChiCTR2000039810 (approved WHO primary register) http://www.chictr.org.cn/showproj.aspx?proj=63662 .

Protein primary structure correlates with calcium oxalate stone matrix preference

Despite the apparent importance of matrix proteins in calcium oxalate kidney stone formation, the complexity of the protein mixture continues to elude explanation. Based on a series of experiments, we have proposed a model where protein aggregates formed from a mixture containing both strongly charged polyanions and strongly charged polycations could initiate calcium oxalate crystal formation and crystal aggregation to create a stone. These protein aggregates also preferentially adsorb many weakly charged proteins from the urine to create a complex protein mixture that mimics the protein distributions observed in patient samples. To verify essential details of this model and identify an explanation for phase selectivity observed in weakly charged proteins, we have examined primary structures of major proteins preferring either the matrix phase or the urine phase for their contents of aspartate, glutamate, lysine and arginine; amino acids that would represent fixed charges at normal urine pH of 6-7. We verified enrichment in stone matrix of proteins with a large number of charged residues exhibiting extreme isoelectric points, both low (pI<5) and high (pI>9). We found that the many proteins with intermediate isoelectric points exhibiting preference for stone matrix contained a smaller number of charge residues, though still more total charges than the intermediate isoelectric point proteins preferring the urine phase. While other sources of charge have yet to be considered, protein preference for stone matrix appears to correlate with high total charge content.

Urinary metabolic profile and stone composition in kidney stone formers with and without heart disease

Objective

Kidney stone disease seems to be associated with an increased risk of incident cardiovascular outcomes; the aim of this study is to identify differences in 24-h urine excretory profiles and stone composition among stone formers with and without cardiovascular disease (CVD).

Methods

Data from patients attending the Department of Renal Medicine’s metabolic stone clinic from 1995 to 2012 were reviewed. The sample was divided according to the presence or absence of CVD (myocardial infarction, angina, coronary revascularization, or surgery for calcified heart valves). Univariable and multivariable regression models, adjusted for age, sex, BMI, hypertension, diabetes, eGFR, plasma bicarbonate and potential renal acid load of foods were used to investigate differences across groups.

Results

1826 patients had available data for 24-h urine analysis. Among these, 108 (5.9%) had a history of CVD. Those with CVD were older, have higher prevalence of hypertension and diabetes and lower eGFR. Univariable analysis showed that patients with CVD had significantly lower 24-h urinary excretions for citrate (2.4 vs 2.6 mmol/24 h, p = 0.04), magnesium (3.9 vs 4.2 mmol/24 h, p = 0.03) and urinary pH (6.1 vs 6.2, p = 0.02). After adjustment for confounders, differences in urinary citrate and magnesium excretions remained significant. No differences in the probability of stone formation or stone compositions were found.

Conclusions

Stone formers with CVD have lower renal alkali excretion, possibly suggesting higher acid retention in stone formers with cardiovascular comorbidities. Randomized clinical trials including medications and a controlled diet design are needed to confirm the results presented here.

Graphic abstract

Clinician Versus Nomogram Predicted Estimates of Kidney Stone Recurrence Risk

Purpose: Kidney stone recurrence rates vary between patients. A patient's risk informs the frequency and intensity of preventative interventions. Clinicians routinely use clinical experience to estimate risk. We sought to compare clinician estimated recurrence risk with the recurrence of kidney stones (ROKS) nomogram. Materials and Methods: We surveyed members of the Endourological Society with clinical expertise in kidney stones. Respondents estimated the risk of recurrence for patients in three clinical vignettes corresponding to low, intermediate, and high recurrence risk from the nomogram. Clinician estimates were compared with ROKS estimates. Results: The majority of the 318 respondents were from North America (n = 127, 40%). The most commonly estimated recurrence was 50% at 5 years. The respondents' estimates were significantly different from the ROKS predicted recurrence rate for all cases (Case 1, 50% vs 93% p < 0.0001; Case 2, 50% vs 60% p < 0.0001; Case 3, 60% vs 22% p < 0.0001). The ROKS predicted estimates ranged from 22% to 93%, whereas the median urologist-derived 5-year risk estimates for each case ranged from 50% to 60%. The median range of estimates by respondents across cases was 20%, narrower than the 71% for the ROKS nomogram. The majority of respondents (95%) do not use nomograms in practice, mostly because of lack of awareness of useful nomograms (59%). Conclusions: This study suggests that clinicians may not be able to distinguish those with high and low recurrence risk when compared with peers and when compared with a nomogram. Clinical decision support tools are needed to enable clinicians to better estimate stone recurrence risk.

Current Status and Role of Patient-reported Outcome Measures (PROMs) in Endourology

Kidney stone disease can have a number of adverse effects on patients including quality of life. Studies assessing outcome measures in this area have largely been focused on objective assessments such as stone free rate. However, as part of the evolution to shift healthcare to a more patient centered position, patient-reported outcome measures have emerged as an improved tool to address this deficit. Key patient-reported outcome measures in Urology now include Ureteral Stent Symptom Questionnaire, Wisconsin Stone QoL Questionnaire, Cambridge Ureteric Stone PROM, Cambridge Renal Stone PROM, and Urinary Stones and Intervention Quality of Life. This article serves to provide an overview of these tools and help delineate their role in current practice.

Association between sex hormones and kidney stones: analysis of the National Health and Nutrition Examination Survey

PURPOSE

Increasing age, male gender, and metabolic syndrome are associated with kidney stone formation. As sex hormones change with age, gender, and metabolic syndrome, we hypothesized that sex hormones may underlie the physiologic changes affecting stone formation.

METHODS

We analyzed the relationships between testosterone, estradiol, and history of kidney stones using data from 10,193 participants in the Continuous National Health and Nutrition Examination Survey (NHANES) database from 2013-2016. We performed logistic regression analysis to analyze the predictive value of low testosterone and low estradiol on the history of kidney stones in both males and females. Self-reported history of kidney stone diagnosis was the outcome.

RESULTS

After adjusting for risk factors known to be associated with nephrolithiasis such as age, race, BMI, and medical comorbidities including: gout, angina, coronary disease, stroke, asthma, hypertension, and diabetes, multiple regression analysis demonstrated that there is no independent association between sex hormones (testosterone and estradiol) and history of kidney stones in either males or females.

CONCLUSIONS

There appears to be no association between sex hormones and history of kidney stones. Whether there is a more complex interaction of sex hormone levels and the shared association with factors such as metabolic syndrome requires additional investigation. Further studies matching menopausal status for women are necessary to further investigate the potential relationship between estrogen and kidney stones.

Influence of climate on the number of hospitalizations for nephrolithiasis in urban regions in Brazil

Introduction:

Nephrolithiasis has a worldwide prevalence of approximately 5 to 15%, and its occurrence is associated with age, sex, race, dietary habits, geographic location, climatic conditions, and other factors. The objective of the present study was to determine the association between climate and the number of hospitalizations for nephrolithiasis (NH) in Brazilian cities located in different climatic regions.

Methods:

We analyzed data from cities with tropical and subtropical climates. The effects of the lowest (LT), mean (MT), and highest (HT) monthly temperatures and relative humidity of the air (RH) were assessed.

Results:

A positive association was found between the number of hospitalizations for nephrolithiasis and temperature ((LT x NH; R²=0.218; P<0.0001) (MT x NH; R²=0.284; P<0.0001) (HT x NH; R²=0.317; P<0.0001)), and a negative association was found between the number of hospitalizations for nephrolithiasis and the relative humidity (RH x NH; R²=0.234; P<0.0001). Interactions were also observed between MT and RH with respect to their effects on the NH, as described by a linear model (NH = 4.688 + 0.296 x MT - 0.088 x RH). The NH was higher in cities with tropical climates than in cities with subtropical climates (82.4 ± 10.0 vs 28.2 ± 1.6; P<0.00001).

Conclusion:

There is an association between the NH and variations in temperature and relative humidity.

Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian-Vegan Diets

Nephrolithiasis is a common medical condition influenced by multiple environmental factors, including diet. Since nutritional habits play a relevant role in the genesis and recurrence of kidney stones disease, dietary manipulation has become a fundamental tool for the medical management of nephrolithiasis. Dietary advice aims to reduce the majority of lithogenic risk factors, reducing the supersaturation of urine, mainly for calcium oxalate, calcium phosphate, and uric acid. For this purpose, current guidelines recommend increasing fluid intake, maintaining a balanced calcium intake, reducing dietary intake of sodium and animal proteins, and increasing intake of fruits and fibers. In this review, we analyzed the effects of each dietary factor on nephrolithiasis incidence and recurrence rate. Available scientific evidence agrees on the harmful effects of high meat/animal protein intake and low calcium diets, whereas high content of fruits and vegetables associated with a balanced intake of low-fat dairy products carries the lowest risk for incident kidney stones. Furthermore, a balanced vegetarian diet with dairy products seems to be the most protective diet for kidney stone patients. Since no study prospectively examined the effects of vegan diets on nephrolithiasis risk factors, more scientific work should be made to define the best diet for different kidney stone phenotypes.

Patient reported outcome measures (PROMs) and patient reported experience measures (PREMs) for Dutch urolithiasis patients

Measuring quality of care with Patient Reported Outcome Measures (PROMs) and Patient Reported Experience Measures (PREMs) is becoming increasingly important. With this study we evaluated ESWL and URS treatments with PROMs/PREMs and gained experience with the execution and implementation of PROMs/PREMs in daily practice. A longitudinal survey study was performed with ESWL and URS urolithiasis patients, using a questionnaire directly (T0-response 69.8%, n = 51) and 10 days after treatment (T1-response 56%, n = 42). Problems on performing daily activities were experienced by 54.2% of ESWL and 61.1% of URS-patients. In the two weeks after treatment 45.8% of the ESWL group and 70.6% of the URS-patients uses pain medication. URS-patients miss more workdays (5.61 versus 1.26 p = 0.025). Patient satisfaction is similar in both groups. With this study we have made a start with PROMs and PREMs for urolithiasis patients. It shows that urolithiasis treatment has influence on patient’s life. More knowledge in this area will improve shared decision making.

Does chronic hyperglycaemia increase the risk of kidney stone disease? results from a systematic review and meta-analysis

DESIGN

Systematic review and meta-analysis of observational studies was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for studies reporting on diabetes mellitus (DM) or metabolic syndrome (MetS) and kidney stone disease (KSD).

OBJECTIVE

To examine the association between chronic hyperglycaemia, in the form of DM and impaired glucose tolerance (IGT) in the context of MetS and KSD.

SETTING

Population-based observational studies. Databases searched: Ovid MEDLINE without revisions (1996 to June 2018), Cochrane Library (2018), CINAHL (1990 to June 2018), ClinicalTrials.gov, Google Scholar and individual journals including the Journal of Urology, European Urology and Kidney International.

PARTICIPANTS

Patients with and without chronic hyperglycaemic states (DM and MetS).

MAIN OUTCOME MEASURES

English language articles from January 2001 to June 2018 reporting on observational studies.

EXCLUSIONS

No comparator group or fewer than 100 patients. Unadjusted values were used for meta-analysis, with further meta-regression presented as adjusted values. Bias was assessed using Newcastle-Ottawa scale.

RESULTS

2340 articles were screened with 13 studies included for meta-analysis, 7 DM (three cohort) and 6 MetS. Five of the MetS studies provided data on IGT alone. These included: DM, n=28 329; MetS, n=31 767; IGT, n=12 770.

CONTROLS

DM, n=5 89 791; MetS, n=1 78 050; IGT, n=2 93 852 patients. Adjusted risk for DM cohort studies, RR=1.23 (0.94 to 1.51) (p<0.001). Adjusted ORs for: DM cross-sectional/case-control studies, OR=1.32 (1.21 to 1.43) (p<0.001); IGT, OR=1.26 (0.92 to 1.58) (p<0.0001) and MetS, OR=1.35 (1.16 to 1.54) (p<0.0001). There was no significant difference between IGT and DM (cross-sectional/case-control), nor IGT and MetS. There was a moderate risk of publication bias. Statistical heterogeneity remained significant in adjusted DM cohort values and adjusted IGT (cross-sectional/case-control), but non-signficant for adjusted DM (cross-sectional/case-control).

CONCLUSION

Chronic hyperglycaemia increases the risk of developing kidney stone disease. In the context of the diabetes pandemic, this will increase the burden of stone related morbidity and mortality.

PROSPERO REGISTRATION NUMBER

CRD42018093382.

Inflammatory serum markers predicting spontaneous ureteral stone passage

INTRODUCTION

Ureteral stones pose a high economic and medical burden among Emergency Department (ED) admissions. Management strategies vary from expectant therapy to surgical interventions. However, predictors of spontaneous ureteral stone passage are still not well understood. We aim to explore the role of neutrophil-to-lymphocyte (NLR) and platelet-to-lymphocyte (PLR) ratios in the spontaneous ureteral stone passage (SSP).

METHODS

Chart review was done for 619 patients who presented to our institution's ED with non-febrile renal colic and received a radiological diagnosis of ureteral stone of less than 10 mm. Demographic, clinical, laboratory, and radiological data were collected. The Linear-by-Linear Association test was used to look at the trend among the NLR and PLR quartiles and other demographic variables. Univariate analysis was run for the collected variables. Then, a hierarchal backward multivariate logistic regression was run for each of NLR and PLR variables. To validate the results, bootstrapping was undertaken for each model.

RESULTS

NLR between 2.87 and 4.87 had odds ratio (OR) 2.96 (95% CI 1.80-5.49) and an NLR > 4.87 had 3.63 (2.04-6.69) the odds of retained ureteral stone. A PLR between 10.42 and 15.25 and a PLR > 15.25 had 3.28 (1.79-6.19) and 3.84 (2.28-7.12) the odds of failed SSP, respectively. Other significant variables in the two models are diabetes, urine leukocyte esterase > 10 white blood cell/μl, moderate-to-severe hydronephrosis, and stone size.

CONCLUSION

NLR and PLR are inversely associated with SSP of ureteral stones. In adjunct with other indicators, NLR and PLR are inflammatory markers that could be used in the clinical decision of ureteral stone management.

Effects on renal outcome of concomitant acute pyelonephritis, acute kidney injury and obstruction duration in obstructive uropathy by urolithiasis: a retrospective cohort study

OBJECTIVE

Obstruction release from urolithiasis can be delayed with a lack of suggested time for preventing the deterioration of renal function. The objective of this study was to investigate the effect of obstruction duration, concomitant acute kidney injury (AKI) or acute pyelonephritis (APN) during the obstruction on the prognosis of renal function.

DESIGN

Retrospective cohort study.

SETTING AND PARTICIPANTS

1607 patients from a urolithiasis-related obstructive uropathy cohort, between January 2005 and December 2015.

OUTCOME MEASURES

Estimated glomerular filtration rate (eGFR) decrease ≥30% and/or end-stage renal disease (ESRD), and eGFR decrease ≥50% and/or ESRD, according to obstruction duration, AKI and APN accompanied by obstructive uropathy.

RESULTS

When the prognosis was divided by obstruction duration quartile, the longer the obstruction duration the higher the probability of eGFR reduction >50% (p=0.02). In patients with concomitant APN or severe AKI during hospitalisation with obstructive uropathy, an eGFR decrease of >30% and >50% occurred more frequently, compared with others (p<0.001). When we adjusted for sex, age, hypertension, diabetes mellitus, APN, AKI grades and obstruction release >7 days for multivariate analysis, we found that concomitant APN (HR 3.495, 95% CI 1.942 to 6.289, p<0.001), concomitant AKI (HR 3.284, 95% CI 1.354 to 7.965, p=0.009 for AKI stage II; HR 6.425, 95% CI 2.599 to 15.881, p<0.001 for AKI stage III) and an obstruction duration >7 days (HR 1.854, 95% CI 1.095 to 3.140, p=0.001) were independently associated with an eGFR decrease >50%. Tree analysis also showed that AKI grade 3, APN and an obstruction duration >7 days were the most important factors affecting renal outcome.

CONCLUSIONS

In patients with urolithiasis-related obstructive uropathy, concomitant APN was strongly associated with deterioration of renal function after obstruction release. The elapsed time to release the obstruction also affected renal function.

Gallic Acid-Chitosan Conjugate Inhibits the Formation of Calcium Oxalate Crystals

It has recently been shown that chitosan (Chit) induces the formation of calcium oxalate (CaOx) crystals, which are mainly responsible for the appearance of kidney stones, and this might limit the use of Chit in vivo. Here, Chit was conjugated with gallic acid (Chit-Gal) to decrease the formation of CaOx crystal. This conjugation was confirmed by FTIR and NMR analyses. Chit-Gal contains 10.2 ± 1.5 mg GA per g of Chit. Compared to the control group, Chit increased the number of crystals by six-fold, mainly in the number of monohydrated CaOx crystals, which are the most harmful CaOx crystals. In addition, Chit increased the zeta potential (ζ) of CaOx crystals by three-fold, indicating that Chit was associated with the crystals. These alterations were abolished when Chit-gal was used in these tests. As oxidative stress is related to renal calculus formation, Chit and Chit-Gal were also evaluated as antioxidants using total antioxidant Capacity (TAC), reducing power, ferrous chelation, and copper chelation tests. Chit-gal was more efficient antioxidant agent in TAC (2 times), in ferrous chelation (90 times), and in reducing Power (5 times) than Chit. Overall, Chit-gal has higher antioxidant activity than Chit, does not induce the formation of CaOx crystals. Thus, Chit-Gal has potential to be used as a chit substitute.

Impact of the Timing of Ureteral Stent Placement on Outcomes in Patients with Obstructing Ureteral Calculi and Presumed Infection

Objective: To understand how time to stent placement impacts outcomes in patients with obstructing ureteral stones and concern for infection. Materials and Methods: Using a prospective urology consult institutional database (2011-2016), we identified patients who presented to the emergency department (ED) with an obstructing ureteral stone, met two or more systemic inflammatory response syndrome (SIRS) criteria (temperature [T] >38°C or <36°C, heart rate >90 beats per minute, respiratory rate >20 breaths per minute, white blood cell count >12 k/μL or <4 k/μ), and underwent stent placement. The primary outcome of interest was impact of stent timing on intensity of care (need for intensive care unit [ICU]) as well as overall length of stay (LOS). Results: Forty-eight patients were identified who met the study criteria. Overall, 58.3% had positive urine cultures. There was no difference between groups with across a range of clinical variables. While the need for ICU admission did not differ between groups, those patients who had a ureteral stent placed within 6 and 10 hours of ED arrival had a significantly decreased LOS (35.6 hours vs 71.6 hours, p = 0.01; 45.7 hours vs 82.4 hours, p = 0.04) relative to those patients who were stented outside these intervals. Conclusion: In patients with an obstructing ureteral calculus and concern for infection, there is a beneficial effect to timelier stent placement in the form of decreased overall LOS.

Twenty-four-hour urine osmolality as a representative index of adequate hydration and a predictor of recurrence in patients with urolithiasis

PURPOSE

To determine the value of 24-h urine osmolality (UOsm) as a representative index of adequate hydration and predictor of stone recurrence in patients with urolithiasis.

METHODS

Medical records of consecutive patients presenting with renal or ureteric stones between 1994 and 2017 were retrospectively reviewed. Patients were grouped according to the results of 24-h UOsm (low ≤ 564 mOsm/kg H₂O, high > 564 mOsm/kg H₂O). Metabolic parameters and risk of stone recurrence were compared between the two groups.

RESULTS

The low urine concentration group were more likely to be older, to be female, and to have a lower body mass index and higher glomerular filtration rate than the high concentration group (each P < 0.005). A positive correlation was seen between 24-h UOsm and urinary calcium, sodium, uric acid, and magnesium excretion and 24-h specific gravity; a negative correlation was seen with 24-h urine volume. Stone-forming constituents, such as calcium and uric acid, were significantly higher in the high urine concentration group. Kaplan-Meier estimates showed that the low urine concentration group had a significantly longer stone recurrence-free period than the high urine concentration group (log-rank test, P < 0.001). In multivariate Cox regression analyses, 24-h UOsm was seen to be an independent risk factor for stone recurrence.

CONCLUSIONS

UOsm is a promising approach to assessing hydration and predicting stone recurrence in patients with urolithiasis. Maintaining UOsm < 564 mOsm/kg H₂O may reduce the risk of stone recurrence.

Caffeine in Kidney Stone Disease: Risk or Benefit?

Kidney stone disease is a global health care problem, with a high recurrence rate after stone removal. It is thus crucial to develop effective strategies to prevent the formation of new or recurrent stones. Caffeine is one of the main components in caffeinated beverages worldwide (i.e., coffee, tea, soft drinks, and energy drinks). Previous retrospective and prospective studies have reported contradictory effects of caffeine on kidney stone risk. Although it has a diuretic effect on enhancing urinary output, it may slightly increase the stone risk index. However, 3 large cohorts have suggested a preventive role of caffeine in kidney stone disease. In addition, a recent in vitro study has addressed relevant mechanisms underlying the preventive role of caffeine against stone pathogenesis. This review summarizes the relevant data from previous evidence and discusses the association between caffeine consumption and kidney stone risk reduction.

Accuracy in 24-hour Urine Collection at a Tertiary Center

There is a paucity of studies addressing the accuracy of 24-hour urine collection for assessing stone risk parameters. Collection accuracy is thought to be essential for assigning optimal therapy for stone prevention. The objective of this study was to determine factors associated with accurate and inaccurate collections. During a 2-year period (2015-2016), 241 stone formers completed 24-hour urine collections. They were divided into accurate collectors (AC), defined as at least one accurate urine collection, and inaccurate collectors (IC). Accuracy was assessed by 24-hour urine creatinine (Cr) excretion indexed to body weight (normal: males, 20-25 mg Cr/kg; females, 15-20 mg Cr/kg). Demographic data analyzed included age, gender, race, insurance status, partner status, income, and education. Statistical analysis methods included the chi-square test, Fisher's exact test, and the two-group t-test. Average age was 50.7 years at the time of collection; 50.2% were men, 86% were white, and 14% were black. Overall, 51.0% of collections were inaccurate. There was no statistical significance between AC and IC for gender (P = 0.85), race (P = 0.90), insurance status (P = 0.85), recurrence (P = 0.87), stone type (P = 0.57), education (P = 0.35), income (P 5 0.42), or poverty (P = 0.35). Older age (P = 0.017) and having a partner (P = 0.022) were significantly associated with AC. The high rate of inaccurate 24-hour urine collections is a concern. The only factors we identified as influencing collection accuracy were age and partner status. These results underscore the importance of developing methods to improve the accuracy of collecting 24-hour urine samples.

The stone surgeon in the mirror: how are German-speaking urologists treating large renal stones today?

OBJECTIVE

To elucidate the current treatment strategies of LRS in German-speaking Europe. Little is known about the treatment of large renal stones (LRS > 3 cm) in daily urological practice. LRS therapy can be, however, challenging and hazardous.

MATERIALS AND METHODS

A 39 item web-based survey was performed among urologists listed by the German, Austrian and Swiss Associations of Urology, addressing professionals treating LRS "on their own" and working in a German-speaking country. Uniparametric descriptions indicated as absolute numbers and percentages without p values, simple linear associations and bubble plots without arithmetic means or bar charts with standard deviation between targeted parameters and percentages were used.

RESULTS

266 of the 6586 responding urologists claimed to treat urinary stones on a regular basis. The majority of them were male (90.2%) and over 50 years old (42.9%). Most stones are treated in non-university hospitals (69.5%). 81.9% of all the institutions treat more than 150 cases/y. Open surgery is still performed in 45.5% of the centres, laparoscopy in 32%. Percutaneous nephrolithotomy (PNL) is the primary treatment option. Antimicrobial strategies vary considerably. Serious complications seem to be rare. However, quite a few responders reported treatment-related deaths. The main limitation is the absolute number of urologists performing LRS treatment, which is unknown.

CONCLUSIONS

The German-speaking urologist treating LRS is a male and over 50. Although he performs PNL primarily, he is not averse to open surgery and SWL. He applies guidelines and employs modern equipment. Only antimicrobial strategies are out of line with the international standards.

Quality of life and urolithiasis: the patient - reported outcomes measurement information system (PROMIS)

Background:

With a high rate of recurrence, urolithiasis is a chronic disease that impacts quality of life. The Patient Reported Outcomes Measurement Information System is an NIH validated questionnaire to assess patient quality of life. We evaluated the impact of urolithiasis on quality of life using the NIH-sponsored PROMIS-43 questionnaire.

Materials and Methods:

Patients reporting to the kidney stone clinic were interviewed to collect information on stone history and demographic information and were asked to complete the PROMIS-43 questionnaire. Quality of life scores were analyzed using gender and age matched groups for the general US population. Statistical comparisons were made based on demographic information and patient stone history. Statistical significance was P<0.05.

Results:

103 patients completed the survey. 36% of respondents were male, the average age of the group was 52 years old, with 58% primary income earners, and 35% primary caregivers. 7% had never passed a stone or had a procedure while 17% passed 10 or more stones in their lifetime. Overall, pain and physical function were worse in patients with urolithiasis. Primary income earners had better quality of life while primary caregivers and those with other chronic medical conditions were worse. Patients on dietary and medical therapy had better quality of life scores.

Conclusions:

Urolithiasis patients subjectively have worse pain and physical function than the general population. The impact of pain on quality of life was greatest in those patients who had more stone episodes, underscoring the importance of preventive measures. Stone prevention measures improve quality of life.

Flexible ureterorenoscopy in position or fusion anomaly: Is it feasible?

OBJECTIVE

To analyze the results of flexible ureterorenoscopy (F-URS) with holmium laser in the treatment of kidney stones with ectopic and fusion anomalies (horseshoe kidney and rotation anomalies).

METHOD

We reviewed data from 13 patients with fusion and ectopic renal anomalies that underwent F-URS from April 2011 to April 2017. We analyzed demographic and clinical data (age, gender, BMI, anatomical abnormality, location and dimension of the renal calculi) and perioperative data (method of treatment, stone-free rate, number of days with DJ catheter and perioperative complications).

RESULTS

The mean stone size was 12.23 +/- 5.43 mm (range 6-22mm), located in the inferior (58.33%) and middle (16.76%) calyceal units, renal pelvis (16.67%) and multiple locations (8.33%). All 13 patients were treated with Ho-Yag laser, using dusting technique (25%), fragmentation and extraction of the calculi (58.33%) and mixed technique (16.67%). We did not have any severe perioperative complication. After 90 days, nine patients (75%) were considered stone free.

CONCLUSION

Our data suggest that F-URS is a safe and feasible choice for the treatment of kidney stones in patients with renal ectopic and fusion anomalies.

Current practice of antibiotic utilization for renal colic in the emergency room

INTRODUCTION

Urinalysis (UA) in the emergency setting for patients with nephrolithiasis produces potentially confusing results leading to treatment of presumed urinary tract infections (UTIs). Our objective was to evaluate the use of antibiotics in patients with nephrolithiasis in a large network of emergency departments (EDs).

METHODS

A retrospective analysis of all ED visits associated with an ICD-9 diagnosis of nephrolithiasis and a CT scan between 2010 and 2013 was performed. Urinalysis data, the use of IV and PO antibiotics during the ED visit and at discharge were assessed. The presence of fever, elevated serum WBCs, >5 WBCs per hpf, and/or dip positive nitrites were used as appropriate criteria for antibiotic use.

RESULTS

Urinalysis data were available for 3,518 (70%) of 5,035 patients with an ED diagnosis of nephrolithiasis and CT imaging. Of these visits, 237 patients had positive nitrites (6.7%) and 864 had >5 WBCs per hpf (24.6%) with 158 (4.5%) having both findings for a total of 943 patients. Intravenous antibiotics were given to 244 patients (25.9%) and oral antibiotics were given to 629 patients (66.7 %) with positive UA findings. Of the 2,440 patients with a negative UA and no leukocytosis or fever, 86 patients (3.5%) received IV antibiotics and 533 patients (21.8%) received PO antibiotics upon discharge.

CONCLUSIONS

Proper treatment of nephrolithiasis in the ED includes the screening and diagnosis of concomitant UTIs. However, correct interpretation of UA studies is vital to the correct implementation of antibiotic therapy. This study suggests that 1/3 of patients were undertreated and 21.8% were over-treated.