Evaluation of the economic burden of kidney stone disease in the UK: a retrospective cohort study with a mean follow-up of 19 years

Does pre-stenting influence outcomes of shockwave lithotripsy? A systematic review and meta-analysis

OBJECTIVE

To determine whether preoperative use of JJ stents in patients undergoing shockwave lithotripsy (SWL) impacts on stone clearance and the rate of postoperative complications.

PATIENTS AND METHODS

We screened multiple databases from inception to January 2021, using the relevant search terms for SWL in patients with a preoperative stent. Inclusion criteria were randomised controlled trials of ≥20 patients aged >18 years who had had SWL with a JJ stent. This review has been registered in the International Prospective Register of Systematic Reviews (PROSPERO; registration number CRD42023443195). Statistical analysis was performed using 'meta' in R.

RESULTS

There were seven eligible studies (403 patients receiving JJ stents and 394 controls). There was no significant difference in the stone-free rate (SFR) following SWL with a JJ stent compared to SWL alone. When considering the complication rates, there was a significantly reduced risk of steinstrasse in patients with a JJ stent. However, there was no significant difference in the risk of other complications including pain, fever, and haematuria, and no significant difference in the likelihood of requiring auxiliary procedures or re-treatment.

CONCLUSIONS

There was a reduced risk of steinstrasse in patients undergoing SWL with a JJ stent compared to SWL alone. However, there was no significant difference in the risk of other postoperative complications. Use of a JJ stent had no effect on the efficacy of SWL, with no significant difference in the SFR.

Association between tea consumption and risk of kidney stones: results from dose-response meta-analysis of prospective studies and Mendelian randomization analysis

PURPOSE

The association between tea consumption and kidney stones is inconsistent in observational studies. Thus, we performed a dose-response meta-analysis of prospective cohort studies and a two-sample Mendelian randomization (MR) analysis to identify this association.

METHODS

The prospective cohort studies reporting the relationship between tea consumption and kidney stones were searched from PubMed, the Cochrane Library, EMBASE, and Web of Science from inception to December 1, 2023. For MR analysis, the summary-level data for tea consumption and kidney stones were extracted from the UK Biobank available data and the 8th release of the FinnGen consortium, respectively. The inverse-variance weighted (IVW) method was the primary analytical method.

RESULTS

In our dose-response meta-analysis, four prospective cohort studies involving 1,263,008 participants were included, and tea consumption was found to have significant associations with kidney stones (RR: 0.80, 95% CI: 0.73-0.87). We also observed a substantially linear negative relationship between tea consumption and the risk of kidney stones. In MR analysis, the IVW method indicated that tea consumption was inversely associated with kidney stones (OR: 0.71, 95% CI: 0.53-0.94).

CONCLUSION

Our study confirmed a causal relationship between tea consumption and kidney stones, and higher tea consumption may reduce the risk of kidney stones.

Cymbopogon proximus and Petroselinum crispum seed ethanolic extract/Gum Arabic nanogel emulsion: Preventing ethylene glycol and ammonium chloride-induced urolithiasis in rats

Urolithiasis is a prevalent urological disorder that contributes significantly to global morbidity. This study aimed to assess the anti-urolithic effects of Cymbopogon proximus (Halfa Bar) and Petroselinum crispum (parsley) seed ethanolic extract /Gum Arabic (GA) emulsion, and its nanogel form against ethylene glycol (EG) and ammonium chloride (AC)-induced experimental urolithiasis in rats. Rats were divided into four groups: group 1 served as the normal control, group 2 received EG with AC in drinking water for 14 days to induce urolithiasis, groups 3 and 4 were orally administered emulsion (600 mg/kg/day) and nanogel emulsion (600 mg/kg/day) for 7 days, followed by co-administration with EG and AC in drinking water for 14 days. Urolithiatic rats exhibited a significant decrease in urinary excreted magnesium, and non-enzymic antioxidant glutathione and catalase activity. Moreover, they showed an increase in oxalate crystal numbers and various urolithiasis promoters, including excreted calcium, oxalate, phosphate, and uric acid. Renal function parameters and lipid peroxidation were intensified. Treatment with either emulsion or nanogel emulsion significantly elevated urolithiasis inhibitors, excreted magnesium, glutathione levels, and catalase activities. Reduced oxalate crystal numbers, urolithiasis promoters' excretion, renal function parameters, and lipid peroxidation while improving histopathological changes. Moreover, it decreased renal crystal deposition score and the expression of Tumer necrosis factor-α (TNF-α) and cleaved caspase-3. Notably, nanogel emulsion showed superior effects compared to the emulsion. Cymbopogon proximus (C. proximus) and Petroselinum crispum (P. crispum) seed ethanolic extracts/GA nanogel emulsion demonstrated protective effects against ethylene glycol induced renal stones by mitigating kidney dysfunction, oxalate crystal formation, and histological alterations.

StoneMod 2.0: Database and prediction of kidney stone modulatory proteins

Stone modulators are various kinds of molecules that play crucial roles in promoting/inhibiting kidney stone formation. Several recent studies have extensively characterized the stone modulatory proteins with the ultimate goal of preventing kidney stone formation. Herein, we introduce the StoneMod 2.0 database (https://www.stonemod.org), which has been dramatically improved from the previous version by expanding the number of the modulatory proteins in the list (from 32 in the initial version to 17,130 in this updated version). The stone modulatory proteins were recruited from solid experimental evidence (via PubMed) and/or predicted evidence (via UniProtKB, QuickGO, ProRule, STITCH and OxaBIND to retrieve calcium-binding and oxalate-binding proteins). Additionally, StoneMod 2.0 has implemented a scoring system that can be used to determine the likelihood and to classify the potential stone modulatory proteins as either "solid" (modulator score ≥ 50) or "weak" (modulator score < 50) modulators. Furthermore, the updated version has been designed with more user-friendly interfaces and advanced visualization tools. In addition to the monthly scheduled update, the users can directly submit their experimental evidence online anytime. Therefore, StoneMod 2.0 is a powerful database with prediction scores that will be very useful for many future studies on the stone modulatory proteins.

Use of Temporally Validated Machine Learning Models To Predict Outcomes of Percutaneous Nephrolithotomy Using Data from the British Association of Urological Surgeons Percutaneous Nephrolithotomy Audit

BACKGROUND AND OBJECTIVE

Machine learning (ML) is a subset of artificial intelligence that uses data to build algorithms to predict specific outcomes. Few ML studies have examined percutaneous nephrolithotomy (PCNL) outcomes. Our objective was to build, streamline, temporally validate, and use ML models for prediction of PCNL outcomes (intensive care admission, postoperative infection, transfusion, adjuvant treatment, postoperative complications, visceral injury, and stone-free status at follow-up) using a comprehensive national database (British Association of Urological Surgeons PCNL).

METHODS

This was an ML study using data from a prospective national database. Extreme gradient boosting (XGB), deep neural network (DNN), and logistic regression (LR) models were built for each outcome of interest using complete cases only, imputed, and oversampled and imputed/oversampled data sets. All validation was performed with complete cases only. Temporal validation was performed with 2019 data only. A second round used a composite of the most important 11 variables in each model to build the final model for inclusion in the shiny application. We report statistics for prognostic accuracy.

KEY FINDINGS AND LIMITATIONS

The database contains 12 810 patients. The final variables included were age, Charlson comorbidity index, preoperative haemoglobin, Guy's stone score, stone location, size of outer sheath, preoperative midstream urine result, primary puncture site, preoperative dimercapto-succinic acid scan, stone size, and image guidance (https://endourology.shinyapps.io/PCNL_Demographics/). The areas under the receiver operating characteristic curve was >0.6 in all cases.

CONCLUSIONS AND CLINICAL IMPLICATIONS

This is the largest ML study on PCNL outcomes to date. The models are temporally valid and therefore can be implemented in clinical practice for patient-specific risk profiling. Further work will be conducted to externally validate the models.

PATIENT SUMMARY

We applied artificial intelligence to data for patients who underwent a keyhole surgery to remove kidney stones and developed a model to predict outcomes for this procedure. Doctors could use this tool to advise patients about their risk of complications and the outcomes they can expect after this surgery.

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.

The association of visceral adiposity index with the risk of kidney stone and kidney stone recurrence

AIM

Our aim in this study was primarily to assess the relationship between visceral adiposity index (VAI) and the risk of kidney stones and kidney stone recurrence in US adults.

METHODS

We used data from the National Health and Nutrition Examination Survey (NHANES) 2007-2014 for our analysis. VAI was calculated from waist circumference (WC), body mass index (BMI), triglycerides (TG), and high-density lipoprotein-cholesterol (HDL-C). Kidney stones and recurrence of kidney stones were obtained from questionnaire interview data. We used multivariate logistic regression analysis to explore the correlation between VAI and the risk of kidney stone and kidney stone recurrence. In addition, we performed subgroup analysis, interaction tests, and restricted cubic spline (RCS) analysis.

RESULTS

A total of 9886 participants were included in this study, with a prevalence of 9.24% for kidney stones and 2.97% for recurrence of kidney stones. The prevalence of kidney stones and kidney stone recurrence increased with higher quartiles of VAI. We observed a significantly positive correlation between VAI and the risk of kidney stone and kidney stone recurrence. Participants with the highest VAI quartiles had a 48% (OR: 1.48, 95%CI: 1.08-2.02) and 52% (OR: 1.52, 95%CI: 0.86-2.71) increased risk of kidney stones and kidney stone recurrence, respectively, compared to participants with the lowest VAI quartiles. Subgroup analysis and interaction tests demonstrated this positive association independent of different subgroup factors.

CONCLUSION

Visceral fat accumulation may be associated with an increased risk of kidney stones and kidney stone recurrence.

Routine Urinary Biochemistry Does Not Accurately Predict Stone Type Nor Recurrence in Kidney Stone Formers: A Multicentre, Multimodel, Externally Validated Machine-Learning Study

Objectives: Urinary biochemistry is used to detect and monitor conditions associated with recurrent kidney stones. There are no predictive machine learning (ML) tools for kidney stone type or recurrence. We therefore aimed to build and validate ML models for these outcomes using age, gender, 24-hour urine biochemistry, and stone composition. Materials and Methods: Data from three cohorts were used, Southampton, United Kingdom (n = 3013), Newcastle, United Kingdom (n = 5984), and Bern, Switzerland (n = 794). Of these 3130 had available 24-hour urine biochemistry measurements (calcium, oxalate, urate [Ur], pH, volume), and 1684 had clinical data on kidney stone recurrence. Predictive ML models were built for stone type (n = 5 models) and recurrence (n = 7 models) using the UK data, and externally validated with the Swiss data. Three sets of models were built using complete cases, multiple imputation, and oversampling techniques. Results: For kidney stone type one model (extreme gradient boosting [XGBoost] built using oversampled data) was able to effectively discriminate between calcium oxalate, calcium phosphate, and Ur on both internal and external validation. For stone recurrence, none of the models were able to discriminate between recurrent and nonrecurrent stone formers. Conclusions: Kidney stone recurrence cannot be accurately predicted using modeling tools built using specific 24-hour urinary biochemistry values alone. A single model was able to differentiate between stone types. Further studies to delineate accurate predictive tools should be undertaken using both known and novel risk factors, including radiomics and genomics.

Rare variants in the sodium-dependent phosphate transporter gene SLC34A3 explain missing heritability of urinary stone disease

Urinary stone disease (USD) is a major health burden affecting over 10% of the United Kingdom population. While stone disease is associated with lifestyle, genetic factors also strongly contribute. Common genetic variants at multiple loci from genome-wide association studies account for 5% of the estimated 45% heritability of the disorder. Here, we investigated the extent to which rare genetic variation contributes to the unexplained heritability of USD. Among participants of the United Kingdom 100,000-genome project, 374 unrelated individuals were identified and assigned diagnostic codes indicative of USD. Whole genome gene-based rare variant testing and polygenic risk scoring against a control population of 24,930 ancestry-matched controls was performed. We observed (and replicated in an independent dataset) exome-wide significant enrichment of monoallelic rare, predicted damaging variants in the SLC34A3 gene for a sodium-dependent phosphate transporter that were present in 5% cases compared with 1.6% of controls. This gene was previously associated with autosomal recessive disease. The effect on USD risk of having a qualifying SLC34A3 variant was greater than that of a standard deviation increase in polygenic risk derived from GWAS. Addition of the rare qualifying variants in SLC34A3 to a linear model including polygenic score increased the liability-adjusted heritability from 5.1% to 14.2% in the discovery cohort. We conclude that rare variants in SLC34A3 represent an important genetic risk factor for USD, with effect size intermediate between the fully penetrant rare variants linked with Mendelian disorders and common variants associated with USD. Thus, our findings explain some of the heritability unexplained by prior common variant genome-wide association studies.

'Like a ticking time bomb': A qualitative study exploring the illness experiences of adults with kidney stone disease

OBJECTIVE

Kidney stone disease (KSD) is a common, complex and painful urological condition, but how patients make sense of and respond to the challenges of KSD is poorly understood. Using the common-sense model of illness self-regulation (CSM-SR), we aimed to explore the illness experiences of individuals with KSD.

DESIGN

A qualitative design using individual semi-structured interviews.

METHODS

Thirty-three patients with KSD attending outpatient urology services participated in interviews informed by the CSM-SR. Data were analysed using reflexive thematic analysis. Themes were mapped onto the domains of the CSM-SR.

RESULTS

Five main themes were generated, broadly echoing domains within the CSM-SR: (1) making sense of KSD, (2) normality paused, (3) the psychological burden of KSD, (4) the tensions of managing KSD, and (5) improving understanding of KSD. Additionally, findings suggested that partners' perceptions of KSD were an additional contextual factor that informed patients' own perceptions and management of KSD. Participants appraised initial KSD symptoms as indicative of a serious health threat. Diagnosis brought some relief, however, KSD wielded multi-dimensional impacts on patients' perceptions, self-management and well-being. Anxiety, including fear of KSD recurrence, and low mood were common psychological burdens across narratives.

CONCLUSION

The majority of the themes identified were commensurate with an extended CSM-SR. This model has utility in informing how patients perceive and manage KSD. Examining patients' KSD representations and routinely assessing for psychological distress may be of benefit to improve health outcomes for this patient group.

Associations between smoke exposure and kidney stones: results from the NHANES (2007-2018) and Mendelian randomization analysis

Purpose

It is currently controversial whether smoke exposure is associated with the risk of kidney stones. Herein, publicly available databases were combined to explore relationships with the risk of nephrolithiasis in terms of smoking status and serum cotinine concentrations.

Materials and methods

First, we conducted an observational study using data from 2007 to 2018, based on the National Health and Nutrition Examination Survey (NHANES) database. Univariate analysis, multivariate logistic regression, trend testing, restricted cubic spline (RCS), and multiple imputation (MI) were the main analytical methods of our study. Then, A Mendelian randomization (MR) analysis was performed to explore the causal relationship between serum cotinine and nephrolithiasis. Genetic instruments for serum cotinine and pooled data for kidney stones were derived from publicly available large-scale genome-wide association studies (GWAS). Inverse-variance weighting (IVW) was the primary method for our MR analysis.

Results

A total of 34,657 and 31,352 participants were included in the observational study based on smoking status and serum cotinine concentrations, respectively. Under full adjustment of covariates, current smokers had an increased risk of kidney stones compared to non-smokers [OR = 1.17 (1.04-1.31), P = 0.009, P for trend = 0.010]. Compared with serum cotinine of <0.05 ng/ml, serum cotinine levels of 0.05-2.99 ng/ml [OR = 1.15 (1.03-1.29), P = 0.013] and ≥3.00 ng/ml [OR = 1.22 (1.10-1.37), P < 0.001] were observed to have a higher risk of nephrolithiasis (P for trend < 0.001). In addition, a non-linear relationship between log2-transformed serum cotinine and the risk of nephrolithiasis was found (P for non-linearity = 0.028). Similar results were found when serum cotinine (log2 transformation) was used as a continuous variable [OR = 1.02 (1.01-1.03), P < 0.001] or complete data was used to analyze after MI. In the MR analysis, genetically predicted high serum cotinine was causally related to the high risk of nephrolithiasis [IVW: OR = 1.09 (1.00-1.19), P = 0.044].

Conclusion

Current smoking and high serum cotinine concentrations may be associated with an increased risk of kidney stones. Further research is needed to validate this relationship and explore its underlying mechanisms.

Characterizations of annexin A1-interacting proteins in apical membrane and cytosolic compartments of renal tubular epithelial cells

Annexin A1 (ANXA1) is a multifunctional calcium-binding protein that can bind to membrane phospholipids. Under high-calcium condition, ANXA1 expression increases on renal epithelial cell surface, leading to enhanced adhesion of calcium oxalate (CaOx) crystal (stone material) onto the cells. To regulate various cellular processes, ANXA1 interacts with many other intracellular protein partners. However, components of the ANXA1-interacting protein complex remain unclear. Herein, we characterized the interacting complexes of apical membrane (ApANXA1) and cytosolic (cyANXA1) forms of ANXA1 in apical membrane and cytosolic compartments, respectively, of renal epithelial cells under high-calcium condition using proteomic and bioinformatic approaches. After fractionation, the ApANXA1- and CyANXA1-interacting partners were identified by immunoprecipitation followed by nanoLC‑ESI‑Qq-TOF tandem mass spectrometry (IP-MS/MS). The ANXA1-interacting partners that were common in both apical membrane and cytosolic compartments and those unique in each compartment were then analyzed for their physico-chemical properties (molecular weight, isoelectric point, amino acid contents, instability index, aliphatic index, and grand average of hydropathicity), secondary structure (α-helix, β-turn, random coil, and extended strand), molecular functions, biological processes, reactome pathways and KEGG pathways. The data demonstrated that each set of these interacting proteins exhibited common and unique characteristics and properties. The knowledge from this study may lead to better understanding of the ApANXA1 and CyAXNA1 biochemistry and functions as well as the pathophysiology of CaOx kidney stone formation induced by high-calcium condition.

The Fate of Residual Fragments After Percutaneous Nephrolithotomy: Results from the Endourologic Disease Group for Excellence Research Consortium

Background: Residual fragments (RFs) after percutaneous nephrolithotomy (PCNL) have a significant impact on patients' quality of life and clinical course. There is a paucity of studies that evaluate the natural history of RFs after PCNL. The objective of this study is to compare rates of reintervention, complications, stone growth, and passage in patients with RFs >4, ≤4, and ≤2 mm after PCNL. Methods: Sites from the Endourologic Disease Group for Excellence (EDGE) research consortium examined data of PCNL patients from 2015 to 2019 with at least 1-year follow-up. RF passage, regrowth, reintervention, and complications were recorded and RFs were stratified into >4 and ≤4 mm groups, as well as >2 and ≤2 mm groups. Potential predictors for stone-related events after PCNL were determined using multivariable logistic regression analysis. It was hypothesized that larger RF thresholds would result in lower passage rates, faster regrowth, and greater clinically significant events (complications and reinterventions) than smaller RF thresholds. Results: A total of 439 patients with RFs >1 mm on CT postoperative day 1 were included in this study. For RFs >4 mm, rates of reintervention were found to be significantly higher and Kaplan-Meier curve analysis showed significantly higher rates of stone-related events. Passage and RF regrowth were not found to be significantly different compared with RFs ≤4 mm. However, RFs ≤2 mm had significantly higher rates of passage, and significantly lower rates of fragment regrowth (>1 mm), complications, and reintervention compared with RFs >2 mm. On multivariable analysis, older age, body mass index, and RF size were found to be predictive of stone-related events. Conclusions: With the largest cohort to date, this study by the EDGE research consortium further confirms that clinically insignificant residual fragment is problematic for patients after PCNL, particularly in older more obese patients with larger RFs. Our study underscores the importance of complete stone clearance post-PCNL and challenges the use of Clinically insignificant residual fragment (CIFR).

Role of Ureteroscopy (URS) and Stone Treatment in Patients with Recurrent UTIs: Outcomes over a 10-Year Period

Background. The study aimed to assess whether the eradication of kidney stones might result in a substantial reduction in the onset of recurrent UTIs. Methods. We selected all the patients who underwent ureteroscopy (URS) for stone disease between 2012 and 2021, with either a history of recurrent UTIs (rUTIs), urosepsis or pre-operative positive urine culture (UC). Data included patient demographics, microbiological data, stone parameters, stone-free and infection-free rates (SFR and IFR, respectively) at follow-up, defined as fragments <2 mm at imaging and the absence of symptoms and urine-culture-proven UTI. Results. Overall, 178 patients were selected. The median age was 62 years. The median cumulative stone size was 10 mm (7-17.25), and the commonest locations were the lower pole (18.9%) and proximal ureter (14.9%). The overall stone-free rate at follow-up was 89.3%. The IFR at 3 months was 88.3%. As follow-up duration increased, the IFR reduced to 85.4%, 74.2%, 68% and 65% at 6, 12, 18 and 24 months, respectively. Patients who had infection recurrence were more likely to present stone persistence or recurrence compared to those who were infection-free at follow-up (20% vs. 4.4%, p = 0.005). Conclusions. SFR after URS is a significant predicting variable for the likelihood of infection-free status at follow-up in patients with an rUTI or positive UC at the time of URS.

Outcomes of alpha-blockers as medical expulsive therapy following shockwave lithotripsy: a systematic review and meta-analysis

OBJECTIVES

To determine stone-free rate following shockwave lithotripsy (SWL) with/without alpha-blockers as well as complication rates (individual and classified using the Clavien-Dindo system).

MATERIALS AND METHODS

We performed a systematic review of all randomized controlled trials that included more than 20 patients (age > 18 years) and examined the use of alpha-blockers after SWL. Meta-analysis was performed using 'metafor' in R. We report risk ratios (RRs) with 95% confidence intervals (95% CIs). The PROSPERO ID for the trial was: CRD42021248108.

RESULTS

We assessed 158 full-text articles and included a total of 21 studies in our review. There were 1445 patients receiving alpha-blockers and 1478 control patients. Those receiving alpha-blockers were significantly more likely to be stone-free (RR 1.12, 95% CI 1.07-1.16; P < 0.001). This effect was robust to 'trim-and-fill' adjustment. In those taking alpha-blockers there was a significant reduction in Clavien III-V complications and, on trim-and-fill adjustment, a significant reduction in Clavien I-II complications. There were also significant reduction in rates of steinstrasse, pain and requirement for auxiliary procedures. There was no significant difference in retreatment rates. These effects were robust to trim-and-fill adjustment.

CONCLUSIONS

There is a modest increase in stone-free rates in those receiving alpha-blockers following SWL, with a reciprocal modest risk reduction for steinstrasse, pain and auxiliary procedures. However, alpha-blockers do not reduce the risk of requiring retreatment.

Clinical characteristics of surgically managed patients with asymptomatic renal stones: Comparison of patients with symptomatic renal stones

PURPOSE

This study aimed to compare the characteristics of asymptomatic and symptomatic nephrolithiasis in patients who underwent surgical treatment for kidney stones.

MATERIALS AND METHODS

Between 2015 and 2019, 245 patients who underwent percutaneous nephrolithotomy or retrograde intrarenal surgery for kidney stones were included. The patients were divided into asymptomatic (n=124) and symptomatic (n=121) groups. All patients underwent blood and urine tests, preoperative non-contrast computed tomography, and postoperative stone composition analysis. We retrospectively analyzed and compared the characteristics of the patients and stones, operation time, stone-free rate, and postoperative complications between the two groups.

RESULTS

In the asymptomatic group, mean body mass index (BMI) was significantly higher (25.7±3.8 kg/m² vs. 24.3±2.8 kg/m², p=0.002) and urine pH was significantly lower (5.6±0.9 vs. 5.9±0.9, p=0.013). The ratio of calcium oxalate dihydrate stones was significantly higher in the symptomatic group (5.3% vs. 15.5%, p=0.023). No significant differences were observed in stone characteristics, postoperative outcomes, or complications. In the multivariate logistic regression analysis for predicting variables for asymptomatic renal stones, BMI (odds ratio [OR], 1.144; 95% confidence interval [CI], 1.038-1.260; p=0.007), and urine pH (OR, 0.608; 95% CI, 0.407-0.910; p=0.016) were independent predictive variables for asymptomatic renal stones.

CONCLUSIONS

This study demonstrated that thorough medical check-ups are needed for the early detection of renal stones in individuals with a high BMI or low urine pH.

Role of Phytotherapy in the Management of BPH: A Summary of the Literature

Benign prostatic hyperplasia (BPH) describes the non-malignant enlargement of the prostate. It is both common and growing in incidence. Treatment is multimodal, involving conservative, medical, and surgical interventions. This review aims to examine the evidence base for phytotherapies, specifically analyzing their role in treating lower urinary tract symptoms (LUTS) attributable to BPH. A literature search was completed, specifically looking for randomized control trials (RCTs) and systematic reviews involving phytotherapy treating BPH. Specific emphasis was placed on exploring substance origin, the proposed mechanism of action, evidence of efficacy, and the side-effect profile. Several phytotherapeutic agents were evaluated. These included serenoa repens, cucurbita pepo, and pygeum Africanum, among others. For most of the reviewed substances, only modest effectiveness was reported. Generally, though, all treatments were tolerated well with minimal side effects. None of the treatments discussed in this paper form part of the recommended treatment algorithm in either European or American guidelines. We, therefore, conclude that phytotherapies, in the treatment of LUTS attributable to BPH, do provide a convenient option for patients, with minimal side effects. At present, however, the evidence for the usage of phytotherapy in BPH is inconclusive, with some agents having more backing than others. This remains an expansive field of urology whereby there is still more research to be done.

Duration of Follow-up and Timing of Discharge from Imaging Follow-up, in Adult Patients with Urolithiasis After Surgical or Medical Intervention: A Systematic Review and Meta-analysis from the European Association of Urology Guideline Panel on Urolithiasis

CONTEXT

No algorithm exists for structured follow-up of urolithiasis patients.

OBJECTIVE

To provide a discharge time point during follow-up of urolithiasis patients after treatment.

EVIDENCE ACQUISITION

We performed a systematic review of PubMed/Medline, EMBASE, Cochrane Library, clinicaltrials.gov, and reference lists according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. Fifty studies were eligible.

EVIDENCE SYNTHESIS

From a pooled analysis of 5467 stone-free patients, we estimated that for a safety margin of 80% for remaining stone free, patients should be followed up using imaging, for at least 2 yr (radiopaque stones) or 3 yr (radiolucent stones) before being discharged. Patients should be discharged after 5 yr of no recurrence with a safety margin of 90%. Regarding residual disease, patients with fragments ≤4 mm could be offered surveillance up to 4 yr since intervention rates range between 17% and 29%, disease progression between 9% and 34%, and spontaneous passage between 21% and 34% at 49 mo. Patients with larger residual fragments should be offered further definitive intervention since intervention rates are high (24-100%). Insufficient data exist for high-risk patients, but the current literature dictates that patients who are adherent to targeted medical treatment seem to experience less stone growth or regrowth of residual fragments, and may be discharged after 36-48 mo of nonprogressive disease on imaging.

CONCLUSIONS

This systematic review and meta-analysis indicates that stone-free patients with radiopaque or radiolucent stones should be followed up to 2 or 3 yr, respectively. In patients with residual fragments ≤4 mm, surveillance or intervention can be advised according to patient preferences and characteristics, while for those with larger residual fragments, reintervention should be scheduled.

PATIENT SUMMARY

Here, we review the literature regarding follow-up of urolithiasis patients. Patients who have no stones after treatment should be seen up to 2-3 yr, those with large fragments should be reoperated, and those with small fragments could be offered surveillance with imaging.

Best Practice in Interventional Management of Urolithiasis: An Update from the European Association of Urology Guidelines Panel for Urolithiasis 2022

PURPOSE

The European Association of Urology (EAU) has updated its guidelines on clinical best practice in urolithiasis for 2021. We therefore aimed to present a summary of best clinical practice in surgical intervention for patients with upper tract urolithiasis.

MATERIALS AND METHODS

The panel performed a comprehensive literature review of novel data up to May 2021. The guidelines were updated and a strength rating was given for each recommendation, graded using the modified Grading of Recommendations, Assessment, Development, and Evaluations methodology.

RESULTS

The choice of surgical intervention depends on stone characteristics, patient anatomy, comorbidities, and choice. For shockwave lithotripsy (SWL), the optimal shock frequency is 1.0-1.5 Hz. For ureteroscopy (URS), a postoperative stent is not needed in uncomplicated cases. Flexible URS is an alternative if percutaneous nephrolithotomy (PCNL) or SWL is contraindicated, even for stones >2 cm. For PCNL, prone and supine approaches are equally safe. For uncomplicated PCNL cases, a nephrostomy tube after PCNL is not necessary. Radiation exposure for endourological procedures should follow the as low as reasonably achievable principles.

CONCLUSIONS

This is a summary of the EAU urolithiasis guidelines on best clinical practice in interventional management of urolithiasis. The full guideline is available at https://uroweb.org/guidelines/urolithiasis.

PATIENT SUMMARY

The European Association of Urology has produced guidelines on the best management of kidney stones, which are summarised in this paper. Kidney stone disease is a common condition; computed tomography (CT) is increasingly used to diagnose it. The guidelines aim to decrease radiation exposure to patients by minimising the use of x-rays and CT scans. We detail specific advice around the common operations for kidney stones.

Changes in Urine Composition and Risk of Kidney Stone Disease Following Bariatric Surgery: A Systematic Review over Last 2 Decades

PURPOSE OF REVIEW

The association of kidney stone disease (KSD) and gastrointestinal (GI) surgery has been well established. With a rising obesity crisis, we wanted to see the correlation of urinary composition in patients undergoing bariatric surgery and their risk of KSD. The objective of this paper is to perform a systematic review and meta-analysis of literature to evaluate the changes in urinary composition and risk of KSD following bariatric surgery.

RECENT FINDINGS

A total of seven studies (2498 patients) underwent bariatric surgery with a mean age of 46.7 years and a male:female ratio of 1:3. The most popular bariatric surgery was the Roux-en-Y procedure. Meta-analysis of the studies showed that significant decrease in urinary calcium, citrate, and urate, and increase in urinary oxalate. There was also a nonsignificant volume reduction in the post-operative cohort. The decrease in urinary citrate and increase in urinary oxalate are both predisposing factors of stone formation. There is strong evidence that bariatric surgery results in significant changes in urine composition in keeping with the increased risk of developing KSD. This identifies useful therapeutic targets in the prophylactic management of patients who have undergone bariatric surgery.

Financial Toxicity of Nephrolithiasis: The First Assessment of the Economic Stresses of Kidney Stone Treatment

OBJECTIVE

To investigate the financial toxicity (FT) related to kidney stone treatment.

METHODS

We performed a cross-sectional cohort study with multi-institutional in-person and online cohorts of stone formers.  Participants were surveyed using the validated COST tool (COmprehensive Score for financial Toxicity). The maximum score is 44 and lower scores indicate increased FT. "Moderate FT" was defined by COST scores between 25-14 points and "severe FT" for scores <14. Descriptive statistics, X² tests, T tests, Spearman correlation, and logistic regression were performed using SPSS v28.

RESULTS

241 participants were surveyed, including 126 in-person participants and 115 online. 60% of participants reported at least moderate FT (COST score <26) and 26% reported severe FT (COST score <14). Patients who reported moderate to severe FT were younger than those with low FT by a median difference of 8 years (95%CI = 4, 12). There was a significant correlation between out-of-pocket expense and COST scores, such that as out-of-pocket expenses increased, COST scores decreased, (Spearman's rho =-0.406, p = <0.001). Participants with moderate to severe FT tended to miss more workdays (p = 0.002), and their caretakers tended to miss more workdays (p = 0.007) due to their stone disease.

CONCLUSIONS

Most participants reported moderate to severe FT. As prior studies have shown that patients with "moderate FT" employ cost-coping strategies (i.e., medication rationing) and those with "severe FT" have worse health outcomes, urologists need to be sensitive to the financial burdens of treatment experienced by such patients undergoing kidney stone treatment.

Impact of COVID-19 on the management and outcomes of ureteric stones in the UK: a multicentre retrospective study

OBJECTIVES

To determine if management of ureteric stones in the UK changed during the coronavirus disease 2019 (COVID-19) pandemic and whether this affected patient outcomes.

PATIENTS AND METHODS

We conducted a multicentre retrospective study of adults with computed tomography-confirmed ureteric stone disease at 39 UK hospitals during a pre-pandemic period (23/3/2019-22/6/2019) and a period during the pandemic (the 3-month period after the first severe acute respiratory syndrome coronavirus-2 case at individual sites). The primary outcome was success of primary treatment modality, defined as no further treatment required for the index ureteric stone. Our study protocol was published prior to data collection.

RESULTS

A total of 3735 patients were included (pre-pandemic 1956 patients; pandemic 1779 patients). Stone size was similar between groups (P > 0.05). During the pandemic, patients had lower hospital admission rates (pre-pandemic 54.0% vs pandemic 46.5%, P < 0.001), shorter mean length of stay (4.1 vs 3.3 days, P = 0.02), and higher rates of use of medical expulsive therapy (17.4% vs 25.4%, P < 0.001). In patients who received interventional management (pre-pandemic 787 vs pandemic 685), rates of extracorporeal shockwave lithotripsy (22.7% vs 34.1%, P < 0.001) and nephrostomy were higher (7.1% vs 10.5%, P = 0.03); and rates of ureteroscopy (57.2% vs 47.5%, P < 0.001), stent insertion (68.4% vs 54.6%, P < 0.001), and general anaesthetic (92.2% vs 76.2%, P < 0.001) were lower. There was no difference in success of primary treatment modality between patient cohorts (pre-pandemic 73.8% vs pandemic 76.1%, P = 0.11), nor when patients were stratified by treatment modality or stone size. Rates of operative complications, 30-day mortality, and re-admission and renal function at 6 months did not differ between the data collection periods.

CONCLUSIONS

During the COVID-19 pandemic, there were lower admission rates and fewer invasive procedures performed. Despite this, there were no differences in treatment success or outcomes. Our findings indicate that clinicians can safely adopt management strategies developed during the pandemic to treat more patients conservatively and in the community.

Variation in Tap Water Mineral Content in the United Kingdom: Is It Relevant for Kidney Stone Disease?

Introduction: The dissolved mineral content of drinking water can modify a number of excreted urinary parameters, with potential implications for kidney stone disease (KSD). The aim of this study is to investigate the variation in the mineral content of tap drinking water in the United Kingdom and discuss its implications for KSD. Methods: The mineral composition of tap water from cities across the United Kingdom was ascertained from publicly available water quality reports issued by local water supply companies using civic centre postcodes during 2021. Water variables, reported as 12-monthly average values, included total water hardness and concentrations of calcium, magnesium, sodium and sulphate. An unpaired t-test was undertaken to assess for regional differences in water composition across the United Kingdom. Results: Water composition data were available for 66 out of 76 cities in the United Kingdom: 45 in England, 8 in Scotland, 7 in Wales and 6 in Northern Ireland. The median water hardness in the United Kingdom was 120.59 mg/L CaCO3 equivalent (range 16.02−331.50), while the median concentrations of calcium, magnesium, sodium and sulphate were 30.46 mg/L (range 5.35−128.0), 3.62 mg/L (range 0.59−31.80), 14.72 mg/L (range 2.98−57.80) and 25.36 mg/L (range 2.86−112.43), respectively. Tap water in England was markedly harder than in Scotland (192.90 mg/L vs. 32.87 mg/L as CaCO3 equivalent; p < 0.001), which overall had the softest tap water with the lowest mineral content in the United Kingdom. Within England, the North West had the softest tap water, while the South East had the hardest water (70.00 mg/L vs. 285.75 mg/L as CaCO3 equivalent). Conclusions: Tap water mineral content varies significantly across the United Kingdom. Depending on where one lives, drinking 2−3 L of tap water can contribute over one-third of recommended daily calcium and magnesium requirements, with possible implications for KSD incidence and recurrence.

Comparison between standard, mini and ultra-mini percutaneous nephrolithotomy for single renal stones: a prospective study

PURPOSE

Based on the current trend of miniaturization of instruments used in percutaneous nephrolithotomy (PCNL), it is necessary to compare different PCNL modalities regarding their access sheath size used. Thus, the safety and efficacy among standard, mini and ultra-mini PCNL (s-PCNL, m-PCNL, um-PCNL) were compared.

METHODS

We performed a prospective, non-randomized trial between January 2018 and July 2020. Patients with stones classified as Guy's stone score grade I were included. The set-up for s-PCNL and m-PCNL included a 30 Fr and 22 Fr percutaneous tract, respectively. In both set-ups, an ultrasonic/ballistic lithotripter was utilized. In the case of um-PCNL, a 12 Fr percutaneous tract was established. A high-power laser was used for lithotripsy. Hemoglobin drop, complication rate, length of hospital stay (LOS), stone-free rate (SFR) and operation time were evaluated.

RESULTS

A total of 84 patients, 28 patients per method, were evaluated. Hemoglobin drop was higher in the s-PCNL group when compared to m-PCNL (p = 0.008) and um-PCNL groups (p < 0.001), while um-PCNL group had the slightest hemoglobin drop. LOS was similar between s-PCNL group and m-PCNL group, but um-PCNL group required shorter hospital stay than the other two modalities (p < 0.001). The complication and transfusion rates as well as SFR did not differ between groups. Operation time in the um-PCNL set-up was longer compared to s-PCNL (p < 0.001) and m-PCNL (p = 0.011), whereas s-PCNL and m-PCNL did not differ significantly.

CONCLUSION

m-PCNL showed less hemoglobin drop, but similar operation time and SFR when compared to s-PCNL. um-PCNL showed even less hemoglobin drop, but the operation time was longer compared to the two other modalities.

Lithotripsy devices for percutaneous nephrolithotomy (PNL) - new developments

PURPOSE OF REVIEW

Percutaneous nephrolithotomy (PNL) is the mainstay of surgery for renal calculi>2 cm or complex multiple calculi and is a technique that has been around since 1976. We review recent literature surrounding novel lithotripsy devices and technology used in PNL.

RECENT FINDINGS

At present, the Holmium:yttrium-aluminum-garnet (Ho:YAG) laser is widely accepted as the gold standard laser lithotripsy for PNL. SwissLithoClast Trilogy offers a range of probes with a trifecta of electromagnetic, ultrasonic energy with surgeon-controlled suction. The Olympus Shockpulse-SE is a similar lithotripter that relies on continuous ultrasonic energy with pulsed ballistic energy to break stones. Thulium Fiber Laser (TFL) offers an alternative laser energy source to the Holmium laser, which has been shown to be very effective at producing small stone fragments and dust. The Moses technology is another addition in a long list of improvements to the Ho:YAG laser, forming vaporization bubble through which more effective energy can be applied to stones.

SUMMARY

Trilogy, Shockpulse, TFL and Moses pulse modulation technology for the Holmium laser all provide improvements compared with older lithotripsy devices. In particular, they convey a safer, efficient and more effective way to manage and clear stones.

Empagliflozin and Decreased Risk of Nephrolithiasis: A Potential New Role for SGLT2 Inhibition?

CONTEXT

Diabetes mellitus is a risk factor for nephrolithiasis. A recent observational study found that in patients with type 2 diabetes (T2D), SGLT2 inhibitor use was associated with a 49% lower risk of nephrolithiasis compared with GLP-1 receptor agonists.

OBJECTIVE

We examined the association between nephrolithiasis and the SGLT2 inhibitor empagliflozin, using existing data from randomized clinical trials.

METHODS

We pooled data from 15 081 T2D patients randomized to empagliflozin (n = 10 177) or placebo (n = 4904) from 20 phase I-IV trials, including the large cardiovascular outcome trial, EMPA-REG OUTCOME. Incident urinary tract stone events were captured using a predefined collection of MedRA terms. A sensitivity analysis using a narrower definition was also performed. Incidence rate ratios (IRR) and 95% CIs were calculated using the relative risk estimate, stratified by study.

RESULTS

The median exposures to study drug were 543 days (placebo) and 549 days (empagliflozin); 183 patients experienced an incident urolithiasis during follow-up (placebo, 79; empagliflozin, 104), yielding annual incidence rates of 1.01 vs 0.63 events/100 patient-years in the 2 respective groups. The IRR was 0.64 (95% CI, 0.48-0.86), in favor of empagliflozin. In the sensitivity analysis, the results were similar (IRR, 0.62 [95% CI, 0.45-0.85]).

CONCLUSION

Compared with placebo, empagliflozin therapy was associated with an approximate 40% reduced risk of urinary tract stone events in T2D patients. The underlying mechanisms are unknown but may involve altered lithogenic profile of the urine. Dedicated randomized prospective clinical trials are warranted to confirm these initial observations in patients with and without T2D.

Chronic hepatitis B virus infection increases the risk of upper urinary calculi

Background

Although hepatitis B virus (HBV) is a recognized risk factor for renal diseases, little is known about HBV infection in individuals with upper urinary calculi (UUC). We investigated the relationship between chronic HBV infection and UUC.

Methods

We retrospectively analysed data from 1399 patients who were discharged from the Department of Urology (2017–2018). The diagnosis of UUC was determined using urinary tract ultrasonography or computed tomography, and HBV infection was evaluated by a positive hepatitis B surface antigen (HBsAg) test. Data on patients with and without UUC and HBsAg-positive and HBsAg-negative patients were compared by univariate and multivariate analyses.

Results

Data on chronic HBV infection and UUC were available for 1062 patients, including 514 who presented with UUC and 548 who did not. Overall, 5.8% of total patients, 8.0% of UUC patients and 3.8% of non-UUC patients had chronic HBV infection. UUC patients (41/514) had a significantly higher prevalence of HBsAg positivity (OR 2.175; 95% CI 1.267–3.734; P = 0.004) than non-UUC patients (21/548). After stratifying by sex, the relative odds of HBsAg positivity were statistically significant in men (OR 2.156; 95% CI 1.162–4.003; P = 0.015) but not in women (OR 2.947; 95% CI 0.816–10.643; P = 0.099). The incidence of urinary pH > 6 and staghorn stones was significantly higher in HBsAg-positive UUC patients than in HBsAg-negative UUC patients.

Conclusion

This is the first study to demonstrate that chronic HBV infection is strongly associated with UUC, at least in men. The urinary pH > 6 and staghorn stones were more common in UUC patients with chronic HBV infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12894-022-01038-z.

Development of a novel predictive model for a successful stone removal after flexible ureteroscopic lithotripsy based on ipsilateral renal function: a single-centre, retrospective cohort study in China

OBJECTIVES

The aims of this study were to investigate the effect of preoperative ipsilateral renal function on the success of kidney stone removal with flexible ureteroscopic lithotripsy and to develop a predictive model based on the results.

DESIGN

Retrospective cohort study.

SETTING

Data from the 2001-2012 period were collected from the electronic records of West China Hospital, Sichuan University.

PARTICIPANTS

576 patients who underwent flexible ureteroscopic lithotripsy were included in the study.

PRIMARY OUTCOME

Stone-free rate (SFR) after the procedures.

RESULTS

In patients with suspected impaired kidney function, the overall SFR was 70.1%. Stone volume (OR 1.46; 95% CI 1.18 to 1.80), lower calyx stones (OR 1.80; 95% CI 1.22 to 2.65), age (OR 1.02; 95% CI 1.00 to 1.04), body mass index (OR 1.10; 95% CI 1.04 to 1.17) and estimated glomerular filtration rate of the affected kidney (OR 0.95; 95% CI 0.94 to 0.97) were identified as independent predictors of SFR. Lasso regression selected the same five predictors as those identified by univariate and multivariate logistic regression analyses, thus verifying our model. The mean area under the curve, based on 1000 iterations and 10-fold validation, was 0.715 (95% CI 0.714 to 0.716). The Hodges-Lehmann test and calibration curve analysis revealed no significant mismatch between the prediction model and the retrospective cohort.

CONCLUSION

Ipsilateral renal function may be a novel independent risk factor for kidney stone removal with flexible ureteroscopic lithotripsy. A novel nomogram for predicting SFR that uses stone volume, lower calyx stones, age, body mass index and estimated glomerular filtration rate was developed, but remains to be externally validated.

Renal and ureteric stones: a clinical review

This clinical review on renal and ureteric stones discusses how stones form, the incidence, risks, and complications associated with calculi. It reflects on the management and treatment options available, and highlights the important contribution by nurses and those working in advanced clinical practice roles in using their knowledge and rational clinical decision making to ensure timely recognition, prompt investigation, management and ongoing health promotion.

Optimal Delivery of Follow-Up Care for the Prevention of Stone Recurrence in Urolithiasis Patients: Improving Outcomes

Urolithiasis is a common clinical condition with frequent recurrences. Advances in knowledge of pathophysiological mechanisms permit the categorization of patients to low and high risk for recurrence, with specific metabolic abnormalities diagnosed in the second category. Follow-up is essential for patients with urolithiasis and consists of both imaging and metabolic follow-up with urine studies. No formal guidelines or solid evidence currently exists regarding frequency and type of follow-up studies to be performed in each category. This review aims to summarize existing evidence regarding follow-up, in order to guide clinicians on how and when to follow-up urolithiasis patients according to existing clinical scenario.

HydroZitLa inhibits calcium oxalate stone formation in nephrolithic rats and promotes longevity in nematode Caenorhabditis elegans

Low fluid intake, low urinary citrate excretion, and high oxidative stress are main causative factors of calcium oxalate (CaOx) nephrolithiasis. HydroZitLa contains citrate and natural antioxidants and is developed to correct these three factors simultaneously. Antioxidants theoretically can prolong the lifespan of organisms. In this study, we preclinically investigated the antilithogenic, lifespan-extending and anti-aging effects of HydroZitLa in HK-2 cells, male Wistar rats, and Caenorhabditis elegans. HydroZitLa significantly inhibited CaOx crystal aggregation in vitro and reduced oxidative stress in HK-2 cells challenged with lithogenic factors. For experimental nephrolithiasis, rats were divided into four groups: ethylene glycol (EG), EG + HydroZitLa, EG + Uralyt-U, and untreated control. CaOx deposits in kidneys of EG + HydroZitLa and EG + Uralyt-U rats were significantly lower than those of EG rats. Intrarenal expression of 4-hydroxynonenal in EG + HydroZitLa rats was significantly lower than that of EG rats. The urinary oxalate levels of EG + HydroZitLa and EG + Uralyt-U rats were significantly lower than those of EG rats. The urinary citrate levels of EG + HydroZitLa and EG + Uralyt-U rats were restored to the level in normal control rats. In C. elegans, HydroZitLa supplementation significantly extended the median lifespan of nematodes up to 34% without altering feeding ability. Lipofuscin accumulation in HydroZitLa-supplemented nematodes was significantly lower than that of non-supplemented control. Additionally, HydroZitLa inhibited telomere shortening, p16 upregulation, and premature senescence in HK-2 cells exposed to lithogenic stressors. Conclusions, HydroZitLa inhibited oxidative stress and CaOx formation both in vitro and in vivo. HydroZitLa extended the lifespan and delayed the onset of aging in C. elegans and human kidney cells. This preclinical evidence suggests that HydroZitLa is beneficial for inhibiting CaOx stone formation, promoting longevity, and slowing down aging.

Diet-Derived Antioxidants and Risk of Kidney Stone Disease: Results From the NHANES 2007-2018 and Mendelian Randomization Study

We aimed to explore the associations between diet-derived antioxidants and kidney stone disease (KSD) risk in this study. We performed weighted multivariable-adjusted logistic regression to assess the associations between the six main diet-derived antioxidants and the risk of KSD by using data from the National Health and Nutrition Examination Survey (NHANES) 2007–2018. Then, we used the Mendelian randomization (MR) approach to verify the causal relationships between circulating antioxidants levels and KSD risk. Genetic tools were extracted from published genome-wide association studies (GWAS). Summary data for KSD was from the FinnGen study and UK biobank. Inverse variance weighted (IVW) was the primary analysis. The 26,438 participants, including 2,543 stone formers, were included for analyses. There were no significant associations between retinol, vitamin B6, vitamin C, vitamin E, and lycopene intake with the risk of KSD across all the quartile categories. Similarly, pooled odds ratio (OR) for KSD risk in genetically predicted per unit change were 1.25 (95% CI: 0.39, 4.02; p = 0.712), 1.14 (95% CI: 0.84, 1.53; p = 0.400), 0.75 (95% CI: 0.52, 1.10; p = 0.141), 1.66 (95% CI: 0.80, 3.46; p = 0.178), 1.27 (95% CI: 0.29, 5.62; p = 0.756), and 0.92 (95% CI: 0.76, 1.12; p = 0.417) for retinol, β-carotene, vitamin B6, vitamin C, α-tocopherol, and lycopene, respectively. The above estimates were replicated in the secondary analyses using UK biobank data. Our study did not support a causal association between circulating antioxidants levels and KSD risk. However, these findings should be verified in larger sample-size MR due to the pleiotropy and other limitations.

Is the visceral adiposity index a potential indicator for the risk of kidney stones?

OBJECTIVE

To determine whether the visceral adiposity index (VAI) was linked to the risk of kidney stones (KS) in the representative U.S. adults.

METHODS

We investigated 59842 participants who joined the 2007-2018 National Health and Nutrition Examination Survey. The association between the visceral adiposity index (VAI) and KS was identified by logistic regression analysis. Meanwhile, the subgroup analysis as well as the calculation of dose-response curves were also utilized to identify sensitive groups.

RESULTS

Data from 29384 participants were available, including 2781 self-reported ever experiencing KS diseases. Overall, the VAI was 0.74 (0.70, 0.78) in the KS group, while 0.55 (0.52, 0.57) in the control group. After adjusting for confounders, the prevalence of KS increased by 13% for each unit of VAI increment (OR = 1.13, 95% CI: 1.08, 1.19). Moreover, a linear relationship was found between the VAI and the prevalence of KS. By subgroup analysis, we found that a positive correlation between VAI and the risk of KS both in male (OR=1.14, 95%CI:1.07, 1.22) and female (OR=1.14, 95%CI:1.05, 1.24), White (OR=1.20, 95%CI:1.11, 1.28) and other race, all aged subgroups, nonhypertensive (OR=1.06, 95%CI:1.08, 1.25) and nondiabetic subgroups (OR=1.14, 95%CI:1.07, 1.21).

CONCLUSIONS

Elevated VAI was strongly associated with KS in representative U.S. adults, which may be a promising indicator for the risk of kidney stones.

Decision-Making, Preference, and Treatment Choice for Asymptomatic Renal Stones-Balancing Benefit and Risk of Observation and Surgical Intervention: A Real-World Survey Using Social Media Platform

Introduction: The burden of kidney stone disease has risen, and several treatment options now exist. We wanted to evaluate the preference and treatment choices based on the information provided for management of hypothetical 8 and 15 mm renal stone, and factors that influenced their decision. Materials and Methods: An online questionnaire to investigate trends in decision-making for two hypothesized scenarios of asymptomatic kidney stones (8 and 15 mm) was formatted online in Microsoft Forms and posted on social media (Facebook) in Europe. The ethical approval was obtained from the University Ethics Committee, and data were collected from general public between September and November 2020. Results: A total of 476 participants of different age and background answered the survey with a male:female ratio of 1:2.7. The age groups were categorized as 18-25 years (n = 149), 26-49 years (n = 192), and 50+ years (n = 135). In the 8 mm scenario, 107 of the 476 participants (22.5%) chose observation, 249 (52.3%) chose extracorporeal shockwave lithotripsy (SWL) and 120 (25.2%) opted for ureteroscopy (URS). In the 15 mm scenario, 194 participants chose SWL treatment (40.8%), 216 (45.4%) URS, and 66 (13.9%) preferred percutaneous nephrolithotomy. The influencing factors were success rate, complication risk and invasiveness of the procedure. On comparison to 8 mm stone, while stent avoidance and activity limitation were considered less important with 15 mm stone (p < 0.001), complication rates were considered more important (p < 0.001). Conclusion: More than one treatment choice for kidney stones often exists and clinicians must take patient choice into account via an informed decision-making process. While some might accept a higher risk of invasiveness and complications for higher stone-free rate, others might have a more conservative approach to this. It is about time that urologists take patient priorities and concerns into account and perhaps use Patient Reported Outcome Measures in addition to clinical outcomes when comparing treatment success.

Acupuncture versus Lornoxicam in the Treatment of Acute Renal Colic: A Randomized Controlled Trial

Objective

To compare the analgesic efficacy and safety of acupuncture and lornoxicam in acute renal colic (ARC).

Design, Setting, Participant

A randomized, double-blind, parallel-controlled, single-centered trial was conducted at Susong County People’s Hospital from October 2019 to November 2020. Eighty-four patients with ARC were randomly divided into lornoxicam group (Group L) and acupuncture group (Group A). Group A was treated with acupuncture at Sanyinjiao (SP6), Yinlingquan (SP9) and normal saline, and Group L was treated with sham acupuncture at SP6, SP9 and lornoxicam.

Main Outcome Measures

Visual analogue scale (VAS) scores and adverse reactions such as nausea and dizziness were recorded within 5, 10, 15, 20 and 40 minutes after treatment. The main outcome of this study was the short-term effective (STE) rate, the secondary outcome was the onset time, and the safety index was incidence of adverse reactions.

Results

A total of 80 patients completed this study, including 41 patients (21 males and 20 females) in Group L and 39 patients (21 males and 18 females) in Group A. Group A exhibited lower scores versus group L after treatment (P < 0.05). The overall STE of group L was 61.00% (25/41), significantly lower than group A [84.62% (33/39)] (P < 0.001). There was no difference in the incidence of adverse reactions between group A [2.6% (1/39)] and group L [7.3% (3/41)] (P = 0.616). The ordered logistic regression analysis showed patients receiving acupuncture therapy are more likely to be cured [OR = 2.887, 95% CI: (1.190, 7.000), P = 0.019].

Conclusion

Acupuncture at SP6, SP9 and intramuscular injection of lornoxicam can effectively and safely relieve ARC, but the former has faster and better analgesic effect. Moreover, the incidence of adverse reactions was similar between the two treatments. This acupuncture therapy is recommended as a complementary therapy for ARC.

The development and application of a triage system for urolithiasis during COVID-19

Purpose

To balance epidemic prevention with the therapeutic needs of patients with urolithiasis during the COVID-19 pandemic, we developed a triage system to guide medical staff in making priority decisions.

Methods

The study began with a review of the literature to propose a theoretical framework. Then, focus groups were assembled to develop, supplement, refine and form a consensus on the indications of the triage system. Finally, the system was implemented in the clinic. The validity and reliability of the system were tested by a content validity index and the interrater reliability kappa coefficient. Changes in patient characteristics and waiting time before and after the epidemic were compared.

Results

The theoretical framework was based on disease pathophysiology, including obstruction, infection, kidney dysfunction, and other symptoms. With this guide, a 28-item triage system with categories of T1–5 (low priority to urgent) was developed. The content validity index and the interrater reliability coefficient were 0.833 and 0.812, respectively. During clinical application, although the total number of patients remained steady, the proportion of T1 decreased significantly; even though the overall waiting time of patients did not change significantly, it increased for T1 and decreased for T2–4 in 2020 compared with 2019 (P < 0.05).

Conclusion

This triage tool based on the dimensions of obstruction, infection, kidney dysfunction, and other symptoms has good psychometric properties and significant utility for prioritizing patients with urolithiasis during times of crisis. With this system, patients of moderate to high priority were treated promptly during the COVID-19 pandemic.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-021-03871-7.

Comparison of the Efficacy of Male Sexual Activity Versus Alpha-Blockers in the Expulsion of Distal Ureteric Stones: A Systematic Review and Meta-Analysis

Globally, the prevalence of urolithiasis is increasing, with limited effective treatment options. Though debate exists within the literature, the use of medical expulsive therapy (MET) for distal ureteric stones in the form of alpha-blockers is commonplace. Alpha-blockers work via the inhibition of norepinephrine, resulting in a small degree of distal ureteric relaxation. Nitric oxide (NO), the main neurotransmitter involved in penile erection, causes smooth muscle relaxation of the distal ureter. It is hypothesised that these alternative pathways may achieve the same desire clinical effect. To our knowledge, this is the first meta-analysis comparing the efficacy of male sexual activity, in the form of intercourse or masturbation, to alpha-blockers in the expulsion of ureteric stones. We conducted a comprehensive search of electronic databases (PubMed, MEDLINE, EMBASE, SCOPUS, CENTRAL and Google Scholar), identifying studies comparing male sexual activity versus alpha-blockers, in male patients with distal ureteric stones. The Cochrane risk-of-bias tool was used to assess the included studies. For data analysis, a random effects model was used in the event of significant heterogeneity (>75%), with fixed-effects modelling in the event of low-moderate heterogeneity. A search of electronic databases found three randomised control trials (RCTs), enrolling a total of 262 patients. There was no statistically significant difference observed when patients engaged in sexual activity rather than alpha-blocker, when looking at stone expulsion rate at two weeks (P=0.36), expulsion rate at four weeks (P=0.57), or the mean stone expulsion time (P=0.21). Furthermore, there was no significant difference observed when looking at analgesic requirements (P=0.43), or the requirement for additional procedures (P=0.57). Our meta-analysis demonstrated that male sexual activity as an alternative therapy for distal ureteric stones had comparable outcomes to the use of alpha-blocker, proving a viable alternative therapy in those patients wishing to avoid pharmacological management.

Gender Differences in Kidney Stone Disease (KSD): Findings from a Systematic Review

Purpose of Review

The prevalence of kidney stones is rising and historically carries a preponderance for males. However, recent evidence has questioned whether this gender gap is closing. The aim of this systematic review was to examine this further as well as evaluate possible underlying causes.

Recent Findings

Recent evidence confirms the disparity in kidney stone disease between genders is closing. In the modern era, the rise in prevalence among females has been greater, especially in adolescence. Quality of life is also more adversely affected by kidney stone events among females who are also more likely to develop sepsis after endourological surgery. Males, however, are more likely to present with stone events during periods of high ambient temperatures

Summary

Recent literature demonstrates a temporal change in the disease burden of KSD among men and women. The latter, especially adolescent females, are more likely to develop KSD in their lifetime compared to previous eras. Determining causation is complex and continued research is warranted.

Risk of UTI in kidney stone formers: a matched-cohort study over a median follow-up of 19 years

PURPOSE

To describe risk of UTI in Stone formers comparing to non-stone formers.

METHODS

Retrospective cohort study using electronic records for patients across southern England. Stone formers referred to a tertiary referral centre in Southern England, comparator patients were age and sex matched with 3:1 ratio from same database. Those with no documentation were excluded. UTI defined using ICD-10 codes. Risk of UTI presented as hazard ratio with 95% confidence interval, generated using cox regression. Sample size calculated using 80% power and significance set at 0.05.

RESULTS

Eight hundred and nineteen stone formers were included after 1000 records were screened for inclusion, with 2477 age and sex matched non-stone formers extracted from the same database. Sample size was calculated at 287 per group. Stone formers were at significantly increased risk of developing a UTI (HR 5.67; 95% CI 4.52-7.18, p < 0.001). Median follow-up was 19 years (IQR: 15-22).

CONCLUSIONS

Kidney stone formers are at increased risk of developing urinary tract infections.

Proteomic analysis reveals some common proteins in the kidney stone matrix

Background

Proteins are the most abundant component of kidney stone matrices and their presence may reflect the process of the stone’s formation. Many studies have explored the proteomics of urinary stones and crystals. We sought to comprehensively identify the proteins found in kidney stones and to identify new, reliable biomolecules for use in nephrolithiasis research.

Methods

We conducted bioinformatics research in November 2020 on the proteomics of urinary stones and crystals. We used the ClusterProfiler R package to transform proteins into their corresponding genes and Ensembl IDs. In each study we located where proteomic results intersected to determine the 20 most frequently identified stone matrix proteins. We used the Human Protein Atlas to obtain the biological information of the 20 proteins and conducted Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) analysis to explore their biological functions. We also performed immunohistochemistry to detect the expression of the top five stone matrix proteins in renal tissue.

Results

We included 19 relevant studies for analysis. We then identified 1,409 proteins in the stone matrix after the duplicates were removed. The 20 most-commonly identified stone matrix proteins were: S100A8, S100A9, uromodulin, albumin, osteopontin, lactotransferrin, vitamin K-dependent protein Z, prothrombin, hemoglobin subunit beta, myeloperoxidase, mannan-binding lectin serine protease 2, lysozyme C, complement C3, serum amyloid P-component, cathepsin G, vitronectin, apolipoprotein A-1, eosinophil cationic protein, fibrinogen alpha chain, and apolipoprotein D. GO and KEGG analysis revealed that these proteins were typically engaged in inflammation and immune response.Immunohistochemistry of the top five stone matrix proteins in renal tissue showed that the expression of S100A8, S100A9, and osteopontin increased, while uromodulin decreased in kidney stone patients. Albumin was rarely expressed in the kidney with no significant difference between healthy controls and kidney stone patients.

Conclusion

Proteomic analysis revealed some common inflammation-related proteins in the kidney stone matrix. The role of these proteins in stone formation should be explored for their potential use as diagnostic biomarkers and therapeutic targets for urolithiasis.

Association of Kidney Stone Disease (KSD) with Primary Gastrointestinal Surgery: a Systematic Review over Last 2 Decades

PURPOSE OF REVIEW

We aim to provide an up-to-date literature review to further characterise the association of kidney stone disease (KSD) with gastrointestinal (GI) surgery. As KSD is associated with significant morbidity, it is important to quantify and qualify this association to provide better care and management for the patient subgroup.

OBJECTIVE

To perform a systematic review of the existing literature to evaluate the association of KSD following GI surgery.

METHODS

A literature search was performed of the following databases: MEDLINE, EMBASE, Scopus, Google Scholar, Key Urology, Uptodate and Cochrane Trials from January 2000 to June 2020.

RECENT FINDINGS

A total of 106 articles were identified, and after screening for titles, abstracts and full articles, 12 full papers were included. This involved a total of 9299 patients who underwent primary GI surgery. Over a mean follow-up period of 5.4 years (range: 1-14.4 years), 819 (8.8%) developed KSD, varying from 1.2 to 83% across studies. The mean time to stone formation was approximately 3 years (range: 0.5-9 years). In the 4 studies that reported on the management of KSD (n = 427), 38.6% went on to have urological intervention. There is a high incidence of KSD following primary GI surgery, and after a mean follow-up of 3 years, around 9% of patients developed KSD. While the GI surgery was done for obesity, inflammatory bowel disease or cancer, the risk of KSD should be kept in mind during follow-up, and prompt urology involvement with metabolic assessment, medical and or surgical management offered as applicable.

Urolithiasis prevalence in the Russian Federation: analysis of trends over a 15-year period

PURPOSE

To conduct a comparative analysis of the prevalence of urolithiasis in the Russian Federation.

METHODS

We analysed urolithiasis prevalence and incidence data from 2005 to 2019 (15 years) for the entire population of Russia. Data were provided by the 'Ministry of Health' of the Russian Federation. The prevalence and incidence of urolithiasis were collected and analysed for both adults and children for each region of the Russian Federation over this 15-year period. Statistical analysis was performed using the SPSS Statistics 21 software package (SPSS). Intergroup correlations and differences between samples in the studied parameters were considered significant at p < 0.05.

RESULTS

A total of 656,911 and 889,891 urolithiasis cases were observed in 2005 and 2019, respectively, an increase in urolithiasis prevalence of 35.4% for the study period, with the growth rate that was fairly uniform. The incidence of urolithiasis in the Russian Federation was 176,773 in 2005, while 205,414 new urolithiasis cases were recorded in 2019, with a clear tendency to a rising incidence of urolithiasis, an increase of 16.2% during the study period. The incidence per 100,000 in children remained stable during the entire period of analysis.

CONCLUSION

The incidence and prevalence of urolithiasis in the adult population steadily increased in all regions of the Russian Federation, while the incidence in children remained stable. The incidence of urolithiasis was associated with an increase in the incidence of diabetes mellitus, obesity and meat consumptions, highlighting the strong association of kidney stone disease with these risk factors.

Prediction of burden and management of renal calculi from whole kidney radiomics: a multicenter study

Purpose

To assess if autosegmentation-assisted radiomics can predict disease burden, hydronephrosis, and treatment strategies in patients with renal calculi.

Methods

The local ethical committee-approved, retrospective study included 202 adult patients (mean age: 53 ± 17 years; male: 103; female: 99) who underwent clinically indicated, non-contrast abdomen-pelvis CT for suspected or known renal calculi. All CT examinations were reviewed to determine the presence (n = 123 patients) or absence (n = 79) of renal calculi. On CT images with renal calculi, each kidney stone was annotated and measured (maximum dimension, Hounsfield unit (HU), and combined and dominant stone volumes) using a HU threshold-based segmentation. We recorded the presence of hydronephrosis, number of renal calculi, and treatment strategies. Deidentified CT images were processed with the radiomics prototype (Radiomics, Frontier, Siemens Healthineers), which automatically segmented each kidney to obtain 1690 first-, shape-, and higher-order radiomics. Data were analyzed using multiple logistic regression analysis with areas under the curve (AUC) as output.

Results

Among 202 patients, only 28 patients (18%) needed procedural treatment (lithotripsy or ureteroscopic stone extraction). Gray-level co-occurrence matrix (GLCM) and gray-level run length matrix (GLRLM) differentiated patients with and without procedural treatment (AUC 0.91, 95% CI 0.85–0.92). Higher-order radiomics (gray-level size zone matrix – GLSZM) differentiated kidneys with and without hydronephrosis (AUC: 0.99, p < 0.001) as well those with different stone volumes (AUC up to 0.89, 95% CI 0.89–0.92).

Conclusion

Automated segmentation and radiomics of entire kidneys can assess hydronephrosis presence, stone burden, and treatment strategies for renal calculi with AUCs > 0.85.

Risk of Metabolic Syndrome in Kidney Stone Formers: A Comparative Cohort Study with a Median Follow-Up of 19 Years

Background: Kidney stone formers (SF) are more likely to develop diabetes mellitus (DM), but there is no study examining risk of metabolic syndrome (MetS) in this population. We aimed to describe the risk of MetS in SF compared to non-SF. Methods and Materials: SF referred to a tertiary referral metabolic centre in Southern England from 1990 to 2007, comparator patients were age, sex, and period (first stone) matched with 3:1 ratio from the same primary care database. SF with no documentation or previous MetS were excluded. Ethical approval was obtained and MetS was defined using the modified Association of American Clinical Endocrinologists (AACE) criteria. Analysis with cox proportional hazard regression. Results: In total, 828 SF were included after 1000 records were screened for inclusion, with 2484 age and sex matched non-SF comparators. Median follow-up was 19 years (interquartile range—IQR: 15–22) for both stone formers and stone-free comparators. SF were at significantly increased risk of developing MetS (hazard ratio—HR: 1.77; 95% confidence interval—CI: 1.55–2.03, p < 0.001). This effect was robust to adjustment for pre-existing components (HR: 1.91; 95% CI: 1.66–2.19, p < 0.001). Conclusions: Kidney stone formers are at increased risk of developing metabolic syndrome. Given the pathophysiological mechanism, the stone is likely a ‘symptom’ of an underlying metabolic abnormality, whether covert or overt. This has implications the risk of further stone events and cardiovascular disease.

Role of urinary biomarkers for diagnosis and prognosis of kidney stone disease

PURPOSE OF REVIEW

Urinary biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1) and N-acetyl-B-D-glucosamindase (NAG) are recognised as being useful for the detection of kidney tubular damage but their role in the diagnosis and prognosis of kidney stone disease (KSD) is still unknown. To clarify this, we performed a systematic review of literature in accordance with Cochrane methodology from inception to September 2020.

RECENT FINDINGS

Twelve studies were included and a variety of urinary biomarkers (KIM-1, NGAL, NAG, proteins/peptides, cytokines, CA19-9) were measured in a total of 998 patients with KSD. Despite some contradicting studies, majority of the biomarkers studied showed a significant rise in patients with KSD compared to healthy controls, with levels decreasing after their surgical management, noticed as early as 4 h postprocedure. There was limited evidence of correlation with stone burden and elevated levels were also associated with hydronephrosis and superimposed infections.

SUMMARY

Urinary biomarkers could be used in the diagnosis, prognosis and stone-treatment response in patients with KSD. However, as novel indicators, they may not be reliable as the sole diagnostic or prognostic tool for KSD as they are readily confounded by other causes of kidney injury. Further studies are needed to determine their ability to separate KSD from other causes of obstructive uropathy and acute renal injury.

Variations in the mineral content of bottled 'carbonated or sparkling' water across Europe: a comparison of 126 brands across 10 countries

Introduction

Kidney stone disease is a common disease with high recurrence rates. Sufficient intake of water is the cornerstone in primary prevention of stone disease. However, the mineral composition of water can affect urinary minerals and influence stone formation. The aim of this study is to assess the variation in the mineral composition of bottled sparkling or carbonated drinking water across Europe.

Material and methods

The two largest supermarket chains in each participating country were visited to obtain data on mineral composition regarding bicarbonate, calcium, magnesium, potassium, sodium and sulphates of sparkling or carbonated waters by reading the ingredient labels on the bottles supplied by the manufacturers. Alternatively, the web-shops of these supermarkets were consulted.

Results

In total, 126 sparkling water brands across ten European countries were analysed regarding mineral composition. The median concentrations per mineral varied greatly. The greatest variation in median mineral content was found for sodium and sulphates with levels ranging from 3.1 mg/l to 63.0 mg/l and 6.0 mg/l to 263.0 mg/l respectively. A wide distribution of calcium content was found in Switzerland, with calcium levels reaching up to 581.6 mg/l.

Conclusions

This study confirms that the mineral composition of sparkling or carbonated water varies greatly across Europe. Patients with kidney stone disease should be aware that the mineral content of water may influence stone formation and be mindful of the great variation that exists between different water brands. Mineral water can be a source of potential promotors or inhibitors of stone formation and patients and urologists need to be mindful of this.