Chronological changes in the epidemiological characteristics of upper urinary tract urolithiasis in Japan

Annual record on the number of general urological surgeries registered in the National Clinical Database system between April 2018 and December 2021 in Japan

BACKGROUND

The Japanese National Clinical Database (NCD) is a large-scale, nationwide, web-based data entry system that covers the majority of surgical cases performed in Japan. An NCD specializing in urological surgery was launched based on the NCD system in 2018.

METHODS

All urological surgeries performed at more than 1000 institutions were registered from 2018. We herein report the number of surgeries conducted as stipulated in the "Certified Urology Surgeon Training Curriculum" between April 2018 and December 2021.

RESULTS

A total of 1 377 677 cases were registered from 1185 facilities nationwide under the initiative of the Japanese Urological Association. We examined the number of procedures performed every year for each of the 10 categories.

CONCLUSIONS

The NCD system sustainably provides important information relating to the preoperative status, operational outcome, and best practice for urological surgery in Japan.

Japanese survey of perioperative complications and ureteral stricture after ureteroscopy with laser lithotripsy for upper urinary tract stones in multicenter collaborative study

OBJECTIVES

This study aimed to investigate perioperative complications and the details of postoperative ureteral stricture after ureteroscopy with laser lithotripsy (URS-L) for upper urinary tract stones in Japan.

METHODS

Patient data on intra- and postoperative complications after ureteroscopy using URS-L were retrospectively collected from multiple centers in Japan between April 2017 and March 2020 with the cooperation of the Japanese Society of Endourology and Robotics. Data included the number of patients undergoing URS-L, number and type of intra- and postoperative complications, and detailed characteristics of postoperative ureteral stricture.

RESULTS

In total, 14 125 patients underwent URS-L over 3 years at 82 institutions. Annual URS-L numbers gradually increased from 4419 in 2017, to 4760 in 2018, and 4946 in 2019. The total complication rate was 10.5%, which was divided into intra-operative complications in 1.40% and postoperative complications in 9.18%. The annual incidences of intra- and postoperative complications were not significantly different from year to year (p = 0.314 and p = 0.112). Ureteral perforation, ureteral avulsion, and the intra-operative conversion rate were 1.35%, 0.03%, and 0.02%, respectively. Fever >38°C, septic shock, blood transfusion, and postoperative mortality were 7.44%, 0.81%, 0.07%, and 0.04%, respectively. Ureteral stricture occurred in 0.8% of cases. The median length of stricture site was 10.0 mm and the success rate of stricture treatment was 54.6%.

CONCLUSION

Although URS-L utilization has increased in Japan, the annual complication rate has remained steady. Although URS-L is a useful and less invasive procedure, devastating complications can still occur.

Changes in Urinary Uric Acid Concentration after Dotinurad Administration to Patients with Hyperuricemia: A Post Hoc Analysis of Two Clinical Trials in Japan

Dotinurad has been approved in Japan as a selective urate reabsorption inhibitor for the treatment of gout and hyperuricemia. The relationship between uric acid crystallization and the use of uricosuric drugs is widely acknowledged; however, the relationship between changes in urinary uric acid concentration and urine pH or volume has not been sufficiently analyzed. Therefore, we investigated the changes in urinary uric acid concentration following dotinurad administration as well as the relationship between urine pH or volume and urinary uric acid concentration. This post hoc analysis used data from 2 clinical trials that included 12 and 26 patients with hyperuricemia who received dotinurad treatment (for 7 days on an inpatient basis and 14 weeks on an outpatient basis, respectively). The urinary uric acid concentration transiently increased in the early stages of dotinurad use and when its dose was increased, but decreased over time. No uric acid concentrations exceeded the soluble limit at any urine pH. An inverse correlation was observed between urine volume and urinary uric acid concentration. This study highlights the significance of adequately managing urinary uric acid concentrations by increasing urine volume and alkalinizing urine to prevent uric acid crystallization during dotinurad administration.

Plasma levels and urinary excretion of protein Z in patients with urolithiasis

OBJECTIVES

Protein Z (PZ) is a γ-carboxyglutamic acid protein present in plasma that is involved in blood coagulation. Detailed analysis of urinary stones from patients with urolithiasis has revealed that PZ is often found in urinary stones composed of calcium oxalate monohydrate. In this study, we compared blood and urinary PZ concentrations between healthy individuals and patients with urolithiasis.

METHODS

Plasma and urine were collected from healthy individuals and patients with urolithiasis who provided informed consent. PZ was detected as a urinary stone matrix protein in some of the patients. PZ was quantified by ELISA, creatinine was measured by the enzymatic method, and the total protein concentration was measured by the Bradford method.

RESULTS

The plasma PZ level was 2.54 ± 1.02 μg/mL in healthy individuals and that in urolithiasis patients classified by stone history were from 1.16 ± 0.77 to 3.73 ± 1.09 μg/mL, which was not significantly different. The urinary excretion of PZ (PZ/creatinine) was also not different in patients with urolithiasis and in healthy individuals (from 54.1 ± 40.9 to 95.4 ± 69.4 ng/mg vs. 73.3 ± 36.0 ng/mg). A positive correlation was found between the plasma PZ level and creatinine-corrected urinary PZ concentration (r = 0.46).

CONCLUSIONS

Both the plasma level and urinary excretion of PZ in urolithiasis patients were not significantly different with normal individuals. PZ detected in urinary stones as a matrix protein is thought to be incorporated into urinary stones regardless of blood and urine levels of PZ.

Evaluation of the safety and efficiency of color Doppler ultrasound-guided percutaneous nephrolithotomy in clinical practice: results from a retrospective study

This study evaluated the clinical value of color Doppler ultrasound-guided percutaneous nephrolithotomy (PCNL) in avoiding bleeding caused by punctured blood vessels. Herein, we retrospectively included patients who underwent color Doppler ultrasound-guided PCNL or PCNL using the conventional channel technique from August 2018 to August 2022. The clinical characteristics of patients during surgery, complications, and hospital stay were recorded and compared. Overall, 228 patients were enrolled, with 126 patients (age, 47.6 ± 13.2 years; men: 57.14%) in the color Doppler ultrasound-guided PCNL group and 102 patients (age, 46.6 ± 12.3 years) in the B-mode ultrasound-guided puncture group. The total operation time (63.5 ± 15.5 vs. 61.3 ± 16.3 min, p = .5236) and stone clearance rate (86.50% vs. 83.33%, p = .7139) were similar between the two groups. However, the puncture time for the color Doppler ultrasound-guided PCNL group was longer than that for the B-mode ultrasound-guided puncture group (5.1 ± 2.3 vs. 2.6 ± 1.6 min, p = .0019). Moreover, the length of postoperative hospital stay in the color Doppler ultrasound-guided PCNL group reduced significantly by ∼1 day compared with that in the B-mode ultrasound-guided puncture group (4.5 ± 1.6 vs. 5.6 ± 2.1 days, p = .0087). The blood transfusion rate (1.58% vs. 4.9%, p = .0399), sedation-related adverse event rate (0.79% vs. 2.9%, p = .0332), perineal hematoma incidence (0% vs. 2.94%, p < .0001), and serum decreased hemoglobin levels (12.2 ± 9.7 vs. 23.5 ± 10.1 g/L, p < .001) after color Doppler ultrasound-guided PCNL were significantly lower than those after B-mode ultrasound-guided puncture. The stone clearance rate was similar between the two groups, with a similar operation time. Moreover, color Doppler ultrasound-guided PCNL shortened the postoperative hospital stay and decreased Hb levels, blood transfusion rate, and perineal hematoma incidence.

Application of ultrasound imaging in the treatment of urinary tract stones

Urinary tract stones are a common clinical condition that affect millions of individuals worldwide. The management of these stones has evolved significantly over the past 70 years, and ultrasound imaging has emerged as a valuable tool for diagnosis, treatment planning, and follow-up. This review aims to provide an overview of the application of ultrasound imaging in the treatment of urinary tract stones, highlighting its advantages, limitations, and current advancements in the field.

Stone-event-free survival after ureteroscopic lithotripsy by age: comparison between young and older patients

The aim of this study is to examine stone-event-free survival after ureteroscopic lithotripsy (URSL) and risk factors for stone events by age. We retrospectively collected data of all URSL cases at our institution from 2008 to 2021. A total of 1334 cases were included and divided into young (< 65 years, 792 cases), young-old (65-74 years, 316 cases), old-old (75-84 years, 172 cases), and oldest-old (≥ 85 years, 54 cases) groups. Patient characteristics, surgical outcomes, and postoperative stone events were evaluated. The stone-event-free survival and risk factors were compared between young and older groups. Overall, 214 (16.0%) cases developed stone events during a mean follow-up period of 763 days and the 2-year, 5-year, and 8-year stone-event-free survival rates were 84.5%, 72.2%, and 57.2%, respectively. The numbers of stone events in young, young-old, old-old, oldest-old groups were 133 (16.8%), 53 (16.8%), 21 (12.2%), and 7 (13.0%), respectively. No significant differences were found in stone-event-free survival between the young group and each of the older groups. Residual fragment > 4 mm and stone burden ≥ 15 mm were common risk factors in both young and older groups. Especially in older patients, preoperative stenting, which was most often performed to treat obstructive pyelonephritis, was the third risk factor. In conclusion, stone-event-free survival after URSL was comparable between young and older patients. Residual fragment > 4 mm and stone burden ≥ 15 mm were common risk factors in both groups. Preoperative stenting was an additional risk factor in older patients, suggesting that urinary tract infection may influence stone events.

Safety and efficacy of ureteroscopy for urolithiasis in octogenarians

OBJECTIVE

To examine the safety and efficacy of ureteroscopy (URS) for urolithiasis in octogenarians, and identify preoperative risk factors for the incidence of postoperative complications.

METHODS

The patients who underwent URS for urolithiasis were divided into octogenarians and younger patients (age: <80 years), and the groups were compared regarding their clinical characteristics, intraoperative and postoperative complications, and stone-free rate. The predictors of postoperative complications were evaluated using logistic regression models.

RESULTS

A total of 1207 patients were included, 166 in the octogenarian patient group and 1041 in the younger patient group. The proportion of female patients (p < 0.001), American Society of Anesthesiologists (ASA) score (p < 0.001), rate of preoperative pyelonephritis (p < 0.001), and diabetes mellitus (p = 0.003) were higher in the octogenarian group. No statistically significant differences were found between the two groups regarding stone size, location, and intraoperative complications. Postoperative complications, which reached a significant difference, were observed in 34 (20.5%) octogenarians and 117 (11.2%) younger patients (p = 0.002). However, age itself was not significantly associated with postoperative fever, the most frequent postoperative complication, in multivariate analysis. Female sex, ASA score of ≥3, history of diabetes mellitus, and prolonged operative time (≥120 min) were the significant predictors of fever. The stone-free rate in the octogenarian group was superior to that in the younger patient group (80.1% vs. 70.6%, respectively; p = 0.035).

CONCLUSION

Our results suggest that URS for urolithiasis can be safely and effectively applied to octogenarians in selected cases.

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.

The impacts of metabolic syndrome on the risk of severe urolithiasis

Metabolic syndrome (MetS) is significantly correlated with urolithiasis. However, few studies have evaluated the severity of urolithiasis. This study aimed to investigate the relationship of MetS with severe urolithiasis disease (SUD). The data of 910 patients with urolithiasis in the Department of Urology, Second Hospital of Tianjin Medical University from June 2020 to May 2021 were retrospectively collected. The patients were divided into two groups according to the severity of urolithiasis, and the relationships of MetS and its components with SUD were evaluated. The results showed 605 SUD and 272 Mets patients. Multiple regression analysis showed that middle age, male gender, and MetS increased the risk of SUD, whereas serum magnesium decreased it (P < 0.05). Further analysis revealed that the odds ratio (OR) of SUD increased with MetS grade (0-4) (1.029-2.117). Grade 4 patients had a 2.1-fold higher risk of SUD than grade 0 patients (OR 2.117; 95% CI 1.053-4.256; P = 0.035); hypertension and dyslipidemia were most strongly associated with SUD among the four MetS features (P < 0.05). Additionally, calcium oxalate was the most predominant stone component (78.7%) in the SUD(+) group, which also had stones with higher uric acid and lower calcium oxalate dihydrate levels than those of the SUD(-) group (P < 0.05). Our study concluded that SUD is more common in middle-aged men, MetS is an independent risk factor for SUD. The more severe the MetS, the higher the risk of SUD, in which hypertension and dyslipidemia play major roles.

Variables measured on three-dimensional computed tomography are preferred for predicting the outcomes of shock wave lithotripsy

PURPOSE

Shock wave lithotripsy (SWL) is used to treat upper urinary tract stones. Recently, some volume analyzers have enabled preoperative assessment using three-dimensional computed tomography (3D-CT). We evaluated the efficacy of 3D-CT variables for predicting the outcomes of SWL.

METHODS

The study population included 193 patients who underwent SWL between November 2014 and August 2020. In addition to conventional two-dimensional computed tomography (2D-CT) assessments, 3D-CT assessments of targeted stones were retrospectively performed, and stone size and stone density (SD) were measured. The successful and unsuccessful treatment groups were compared and risk factors for an unsuccessful first SWL session were investigated. The predictive accuracy of variables measured on 3D-CT was evaluated by receiver operating characteristic curves and multivariate analyses.

RESULTS

The success rate of the first SWL session was 73.1%. Stone volume, mean SD and highest SD on 3D-CT were significantly higher in the unsuccessful group than in the successful group. Stone volume showed a higher area under the curve (AUC) than the estimated volumetric stone burden and stone diameter, which were measured on 2D-CT (0.729, 0.683, and 0.672, respectively). The AUCs of the mean SD and highest SD on 3D-CT were higher than those on 2D-CT (0.699, 0.680, 0.617, and 0.627, respectively). Multivariate analyses identified stone volume (≥ 0.29 ml), mean SD on 3D-CT (≥ 421 HU), and absence of hydronephrosis as independent predictive factors for unsuccessful SWL.

CONCLUSION

3D-CT variables were promising predictors of the outcomes of SWL. Preoperative 3D-CT assessment is helpful for selecting favorable patients for SWL.

Independent and interactive effects of kidney stone formation and conventional risk factors for chronic kidney disease: a follow-up study of Japanese men

PURPOSE

To assess the impact of interactions between kidney stone formation and conventional risk factors on incident chronic kidney disease (CKD).

METHODS

A total of 11,402 subjects (men 30-69 years of age, Japanese) without CKD at baseline were observed over an average period of 4 years. Cox proportional hazards regression models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) to determine the association between incident CKD, kidney stone formation, and conventional risk factors (diabetes mellitus, hypertension, overweight/obesity, dyslipidemia, and hyperuricemia/gout). We also examined the interactions of renal stones and the conventional risk factors for CKD.

RESULTS

In total, 2301 men (20.2%) developed incident CKD during the follow-up period. After multivariable adjustment, kidney stones were found to increase the risk of incident CKD (HR 1.16; 95% CI 1.03-1.32). Kidney stone formers with hypertension, dyslipidemia, or hyperuricemia/gout presented a greater risk for incident CKD than those who had either kidney stones or other risk factors. However, no significant interactions between kidney stones and other risk factors were found to increase CKD risk. On the other hand, a negative interactive effect between kidney stones and overweight/obesity was observed, leading to reversed risk of incident CKD in coexistence of both factors.

CONCLUSION

Kidney stones were linked to a higher risk for the development of CKD. However, no positive interactive effects were identified between renal stones and conventional risk factors on the risk of incident CKD.

Risk factors for urolithiasis in patients with Crohn's disease

OBJECTIVE

To study the risk factors for urolithiasis in patients with Crohn's disease.

METHODS

This retrospective study included 1071 patients with Crohn's disease who were treated at a single center. Data pertaining to the following variables were analyzed: sex; age; type of Crohn's disease; number of intestinal resections; residual small intestine length; ileostomy; history of glucocorticoid therapy; and duration of Crohn's disease treatment.

RESULTS

Of the 1071 patients, 34 (28 male and six female) had urolithiasis (urolithiasis group) and 1037 (711 male and 326 female) did not (non-urolithiasis group). The median residual small intestine length measured in the urolithiasis group (280.0 cm) was significantly shorter than that in the non-urolithiasis group (342.5 cm; P < 0.01). Significantly more patients in the urolithiasis group (14/34) received steroid medication than those in the non-urolithiasis group (213/1037; P < 0.01). On multivariate analysis, male sex (odds ratio 3.15; P < 0.05), history of glucocorticoid therapy (odds ratio 3.07; P < 0.05), and shorter residual small intestine length (odds ratio 0.99; P < 0.01) were risk factors for the development of urolithiasis in patients with Crohn's disease.

CONCLUSION

Our results suggest that male sex, history of glucocorticoid therapy, and shorter residual small intestine length are risk factors for urolithiasis in patients with Crohn's disease.

Low bone mineral density is a potential risk factor for symptom onset and related with hypocitraturia in urolithiasis patients: a single-center retrospective cohort study

Background

Patients with urolithiasis have a lower bone mineral density (BMD) than those without stones, suggesting a potential correlation between calcium stone formation and bone resorption disorders, including osteopenia and osteoporosis.

Methods

To investigate the influence of BMD on clinical outcomes in urolithiasis, we performed a single-center retrospective cohort study to analyze patients with urolithiasis who underwent both BMD examination and 24-h urine collection between 2006 and 2015. Data from the national cross-sectional surveillance of the Japanese Society on Urolithiasis Research in 2015 were utilized, and additional data related to urinary tract stones were obtained from medical records. The primary outcome was the development of stone-related symptoms and recurrences during follow-up. A total of 370 patients were included in this 10-year study period.

Results

Half of the patients had recurrent stones, and the two-thirds were symptomatic stone formers. While only 9% of patients had hypercalciuria, 27% and 55% had hyperoxaluria and hypocitraturia, respectively. There was a positive correlation between T-scores and urinary citrate excretion. Both univariate and multivariate analyses demonstrated that female sex was associated with recurrences (odds ratio = 0.44, p = 0.007), whereas a T-score < − 2.5 and hyperoxaluria were associated with symptoms (odds ratio = 2.59, p = 0.037; odds ratio = 0.45, p = 0.01; respectively).

Conclusion

These results revealed that low T-scores might cause symptoms in patients with urolithiasis, suggesting the importance of BMD examination for high-risk Japanese patients with urolithiasis having hypocitraturia.

Prospective evaluation and classification of endoscopic findings for ureteral calculi

Difficulty in performing ureteroscopic lithotripsy (URSL) depends on endoscopic findings surrounding calculi. In this multicentre prospective cohort study of 185 patients with a single ureteral stone who underwent ureteroscopic lithotripsy registered in the SMART study between January 2014 and February 2017, we established a classification of endoscopic findings and analysed risk factors for ureteral changes. We evaluated endoscopic findings (oedema, polyps, ureteral mucosa-stone adherence, and distal ureteric tightness) based on the SMART classification. Operative time and ureteral injuries were significantly correlated with endoscopic finding grades. Multivariate analyses revealed that mucosa-stone adherence (MSA) was strongly affected by hydronephrosis grade (odds ratio, 12.4; p = 0.022) and the interval before surgery (odds ratio, 1.10; p = 0.012). The cutoff value for MSA was 98 days, with a predictive accuracy of 0.78. Risk factors for distal ureteric tightness were age (odds ratio, 0.96; p = 0.004) and early intervention (odds ratio, 0.90; p = 0.023). The cutoff value was 34 days, with a predictive accuracy of 0.72. In conclusion, appropriate intervention around 34 days (limited to 98 days) after symptom onset is necessary for treating ureteral calculi. Even if intervention passed 98 days post-symptom onset, staged URSL, alternative procedures, and detailed informed consent should be planned in advance, assuming strong MSA.

Association of Severe Microscopic Hematuria with Successful Conservative Treatment of Single Uncomplicated Ureteral Calculus: A Multicenter Cohort Study

BACKGROUND

Although detection of microscopic hematuria is a well-known diagnostic method for urolithiasis, its ability to predict urolithiasis treatment outcomes in adults is unknown.

OBJECTIVE

To evaluate the role of microscopic hematuria in conservative treatment of ureteral calculus.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study involved 482 patients who were diagnosed with a single uncomplicated ureteral calculus (≤10 mm) using computed tomography and underwent conservative therapy at two Japanese community hospitals between 2013 and 2018. Patients were divided into three groups according to the severity of microscopic hematuria (no, ≤4; mild to moderate, 5-99; and severe, ≥100 red blood cells per high-power field) and as determined during the first emergency department or urologic outpatient clinic visit.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

A multivariate logistic regression analysis was performed to estimate the odds ratio for successful conservative therapy at 28 d after the diagnosis. Statistical significance was set at p < 0.05.

RESULTS AND LIMITATIONS

Of the 482 patients, 81 (16.8%), 209 (43.4%), and 192 (39.8%) had no, mild to moderate, and severe microscopic hematuria, respectively. After adjustments for six relevant confounders, severe microscopic hematuria showed a significant association with successful conservative therapy at 28 d (adjusted odds ratio, 1.91; 95% confidence interval, 1.02-3.57; p = 0.043), whereas mild to moderate microscopic hematuria did not (adjusted odds ratio, 1.05; 95% confidence interval, 0.57-1.93; p = 0.872) when compared with no microscopic hematuria.

CONCLUSIONS

Severe microscopic hematuria was significantly associated with successful conservative therapy for single uncomplicated ureteral calculus.

PATIENT SUMMARY

Microscopic hematuria might have predictive value for conservative treatment of a single uncomplicated ureteral calculus. Using the presence or absence of blood in urine and other predictive factors, clinicians may lead patients with a single uncomplicated ureteral calculus to successful conservative therapy.

Development and validation of a prediction model for failed shockwave lithotripsy of upper urinary tract calculi using computed tomography information: the S3HoCKwave score

Purpose

To develop and validate a new clinical prediction model that accurately predicts the failure of shockwave lithotripsy (SWL) using information obtained from non-contrast-enhanced computed tomography (NCCT).

Methods

This multicentre retrospective cohort study consecutively enrolled patients diagnosed with upper urinary tract calculi by NCCT at five hospitals in Japan from January 1, 2006 to December 31, 2016. Among the candidate predictors, we selected the six most significant predictors a priori. The main outcome was SWL failure after three sessions. Model calibration was evaluated by the calibration slope and the Hosmer–Lemeshow test. Discrimination was evaluated by the receiver-operating characteristic curves and the area under the curve (AUC). A multivariable logistic regression analysis was performed; based on the estimated β coefficients, predictive scores were generated.

Results

Of 2695 patients, 2271 were included. Patients were divided into the development cohort (1666 patients) and validation cohort (605 patients) according to geographical factors. We developed a clinical prediction model with scores ranging from 0 to 49 points. We named the prediction model the S₃HoCKwave score based on the initials of the predictors (sex, skin-to-stone distance, size, Hounsfield units, colic, and kidney or ureter). As a result of internal validation, the optimism-corrected AUC was 0.72. In the validation cohort, the Hosmer–Lemeshow test did not show statistical significance (P = 0.33), and the AUC was 0.71 (95% confidence interval 0.65–0.76).

Conclusions

The S₃HoCKwave score is easy to understand, has a relatively high predictive value, and allows clinicians to make appropriate treatment selections.

Electronic supplementary material

The online version of this article (10.1007/s00345-020-03125-y) contains supplementary material, which is available to authorized users.

Dotinurad: a novel selective urate reabsorption inhibitor as a future therapeutic option for hyperuricemia

Gout is a chronic inflammatory disease caused by precipitation of urate crystals in the joints, kidneys, and urinary tract. Independent of urate deposition disorders, recent studies have shown a positive association between circulating uric acid (UA) levels and cardiovascular (CV) diseases. These results indicate that UA is a precipitating factor of both gout and the progression of CV diseases, including hypertension and/or chronic kidney disease (CKD). A large body of evidence has shown that UA-lowering therapies are effective in preventing the progression of hypertension/CKD and that a causal relationship exists between serum UA level and CV diseases. Despite the urgent need for effective UA-lowering drugs that can be used to obtain better therapeutic outcomes and prognosis, only few drugs have been developed in the past decades. Recently, febuxostat and topiroxostat, which are xanthine oxidoreductase inhibitors, were developed and used in clinical practice. Of note, after the approval of lesinurad, which is a urate transporter-1 (URAT-1) inhibitor, in the United States in 2015, dotinurad (Fig. 1), a novel promising drug with selective UA reabsorption inhibitory property, was recently developed in Japan in 2018. Dotinurad is indicated for patients with hyperuricemia/gout as most patients with hyperuricemia are classified into “underexcretion type”, which requires the inhibition of URAT-1 to excrete excess UA via the kidney. Focusing on dotinurad, the present study highlighted the multifaceted preliminary new trials that assessed for drug efficacy and safety, pharmacokinetics (PK) according to age and gender, the presence or absence of liver and kidney disorders, drug interactions with NSAID, and non-inferiority of dotinurad to either febuxostat or benzbromarone. A series of studies included in this supplemental review indicate that dotinurad reduces serum UA levels, and its efficacy and safety are similar to those of other UA-lowering agents currently used even in hyperuricemic patients with various clinical conditions. Moreover, two exploratory studies with a small sample size were conducted to compare PK parameters between patients with overproduction- and underexcretion-type hyperuricemia, and results showed that the effects of UA-lowering agents were comparable between the two subtype groups.Fig. 1

Efficacy of Naftopidil as a Medical Expulsive Therapy in Japanese Men With Ureteral Stones: A Prospective Randomized Controlled Study

Background

Naftopidil combined with an antispasmodic agent and a supplement that facilitates stone expulsion has reportedly produced an increased rate of ureteral stone expulsion. A randomized controlled study was conducted to determine the efficacy of naftopidil as a medical expulsive therapy for male patients with ureteral stones.

Methods

Male patients (n = 500) with stones from the upper to the lower ureter were randomized to one of four groups and followed for 1 month to assess spontaneous passage of stones. The control group received only analgesics. The other three groups received daily doses of 240 mg flopropione, an antispasmodic agent and 1,350 mg extract of Quercus salicina Blume/Quercus stenophylla Makino (QS), a supplement that facilitates stone expulsion; 50 mg naftopidil; or 50 mg naftopidil in combination with 240 mg flopropione and 1,350 mg QS. Stone expulsion and characteristics were evaluated by urinalysis; kidney, ureter and bladder X-ray; ultrasound; and computed tomography.

Results

The probability of expulsion of ureteral stones < 6 mm increased 1.570-fold (95% confidence interval (CI): 1.039 - 2.374, P < 0.05) with naftopidil compared to control; the probability of expulsion of a lower ureteral stone < 6 mm increased 1.778-fold (95% CI: 1.066 - 2.965, P < 0.05) with naftopidil compared to control. None of the stones > 6 mm spontaneously passed.

Conclusions

For relatively small ureteral stones < 6 mm, analgesic treatment combined with naftopidil would be the first choice. However, for relatively large ureteral stones > 6 mm, it appears that analgesia is sufficient for initial treatment of ureteral stone.

The Urological Association of Asia clinical guideline for urinary stone disease

The Urological Association of Asia, consisting of 25 member associations and one affiliated member since its foundation in 1990, has planned to develop Asian guidelines for all urological fields. The field of stone diseases is the third of its guideline projects. Because of the different climates, and social, economic and ethnic environments, the clinical practice for urinary stone diseases widely varies among the Asian countries. The committee members of the Urological Association of Asia on the clinical guidelines for urinary stone disease carried out a surveillance study to better understand the diversity of the treatment strategy among different regions and subsequent systematic literature review through PubMed and MEDLINE database between 1966 and 2017. Levels of evidence and grades of recommendation for each management were decided according to the relevant strategy. Each clinical question and answer were thoroughly reviewed and discussed by all committee members and their colleagues, with suggestions from expert representatives of the American Urological Association and European Association of Urology. However, we focused on the pragmatic care of patients and our own evidence throughout Asia, which included recent surgical trends, such as miniaturized percutaneous nephrolithotomy and endoscopic combined intrarenal surgery. This guideline covers all fields of stone diseases, from etiology to recurrence prevention. Here, we present a short summary of the first version of the guideline - consisting 43 clinical questions - and overview its key practical issues.

Recent surgical treatments for urinary stone disease in a Korean population: National population-based study

OBJECTIVES

To provide surgical treatment trends for urinary stone disease in Korea.

METHODS

We analyzed medical service claim data of surgical treatments to urinary stone disease submitted by medical service providers from the Health Insurance Review and Assessment Service from 2009 to 2016.

RESULTS

There was a significantly increasing trend among outpatients and inpatients for urinary stone disease from 2009 to 2016 (R²  = 0.643, P = 0.017; R²  = 0.575, P = 0.029). The number of shock wave lithotripsy for treating urinary stone disease increased by 16% from 89 553 in 2009 to 104 013 in 2016 (R²  = 0.684). The number of ureteroscopic lithotripsy increased by 97% from 6106 in 2009 to 12 057 in 2016 (R²  = 0.99). The number of flexible ureteroscopic lithotripsy increased by 16-fold from 219 in 2009 to 3712 in 2016 (R²  = 0.756). The number of percutaneous nephrolithotomy increased by 99.7% from 919 in 2009 to 1835 in 2016 (R²  = 0.987). The use of non-contrast and contrast-enhanced computed tomography in the diagnostic codes for urinary stone disease increased by 394.8% and 263.3% from 2009 to 2016, respectively (R²  = 0.83; R²  = 0.967). Conversely, the use of intravenous pyelography decreased 26.2% over the same period (R²  = 0.945).

CONCLUSIONS

Outpatient and inpatient procedures for urinary stone disease have increased over the past 8 years in Korea. Shock wave lithotripsy is the most widely used treatment modality for urinary stone disease, and endoscopic surgical procedures are rapidly being implemented. There has been a steep increase in the use of computed tomography, whereas conventional intravenous pyelography is declining.

Chronological changes in epidemiological characteristics of lower urinary tract urolithiasis in Japan

OBJECTIVES

To determine changes and trends in the annual incidence and epidemiological aspects of lower urinary tract stones in Japan.

METHODS

Data about patients who had been diagnosed by urologists in 2015 with first and recurrent lower urinary tract stones were collected from 301 hospitals approved by the Japanese Board of Urology. The estimated annual incidence according to sex, age and stone composition was compared with previous nationwide surveys between 1965 and 2005.

RESULTS

The incidence of lower urinary tract stones in Japan has steadily increased from 4.7 per 100 000 in 1965 to 12.0 per 100 000 in 2015. However, the age standardized annual incidence of lower urinary tract stones has remained relatively stable over the same period at 5.5 per 100 000 and 6.0 per 100 000 in 1965 and 2015, respectively. The increase in incidence was most evident among individuals aged ≥80 years. The incidence of calcium oxalate stones has steadily increased among males and females, whereas that of infection-related stones has significantly decreased from 26.2% to 14.3% among men over the past 50 years.

CONCLUSIONS

Nationwide surveys suggest a steady increase in the incidence of lower urinary tract stones over a 50-year period in Japan. This trend might reflect changes in the aging population and improved Japanese medical standards.