Urolithiasis Incidence Research Articles

Drinking water is the urolithiasis development factor among the rural population of a single region

BACKGROUND: The urolithiasis incidence in the Nizhny Novgorod Region exceeds the national average that determines the importance of analyzing the causes of its development and creating preventive measures. AIM: To evaluate the relationship between the urolithiasis incidence and drinking water composition consumed by the rural population of the Nizhny Novgorod Region. MATERIALS AND METHODS: A chemical analysis of drinking water was performed in 50 rural districts of the Nizhny Novgorod Region (a total of 61 samples). Water was taken from centralized water supply sources, artesian wells and boreholes, and springs. The relationship between the urolithiasis incidence and chemical composition measures of drinking water was assessed. RESULTS: Differences in the impurity content of drinking water were found between districts with different values of urolithiasis incidence. Exceeding the standard values for impurities specified in the Sanitary regulations and standards (SanPin) was most commonly detected in water from districts with the highest incidence of urolithiasis. An increase in the calcium/magnesium ratio was the most commonly noted in drinking water from these districts. In 41 (67.2%) of 61 samples, an increase of calcium level was detected. The hardness of drinking water was higher than the standard in 33.3–38.8% of samples depending on the water intake source. CONCLUSIONS: Drinking water with a high level of hardness and mineralization is one of the etiological factors for the development of urolithiasis in Nizhny Novgorod Region. In rural areas of this region with a high incidence of urolithiasis, the monitoring of the state of central water supply sources and the impurity content in drinking water should be intensified.

Exploring the Impact of Family History, Demographics and Ecological Factors on Urolithiasis Prevalence: Insights from a Nationwide Study.

This study aimed to evaluate the potential risk factors of lifetime urolithiasis occurrence on a nationwide scale in Iran. All data regarding urinary stone events were extracted from the cross-sectional Iran National Stone Survey (INSS) study, and the possible determinants of urolithiasis incidence were evaluated. Our multivariable logistic regression suggested that while older age at presentation, male sex, and a positive family history of urolithiasis in either of the patient's parents or siblings were all significantly associated with an increased odds of lifetime urolithiasis occurrence (all P < .001), a positive family history in one's sister (odds ratio; OR=5.56) or brother (OR=4.70) were the most significant predictors. Moreover, belonging to Baluch ethnicity (i.e., an ethnical group indigenous to the south eastern regions of Iran) and residing in regions with higher water hardness (i.e., total concentration of dissolved minerals) were also associated with an increased odds of urolithiasis occurrence (P < .001 and P=.023, respectively). Conversely, living in regions with higher mean humidity decreased the chances of developing a urinary stone event during one's lifetime (OR=0.62, P <.001). Our results indicated that a constellation of demographic, ecological, and familial risk factors are associated with an elevated risk of developing urinary stones during one's lifetime. These findings can assist in implementing novel regional healthcare policies, considering the specific demographic and ecological characteristics. They also support tailoring personalized preventive strategies, particularly for individuals with multiple nonmodifiable risk factors.

Microbiological Characteristics of Kidney Stones in Patients With Urolithiasis

Microbiological Characteristics of Kidney Stones in Patients With Urolithiasis

Longitudinal trend of urolithiasis incidence rates among world countries during past decades

IntroductionThis study explores the trend of urolithiasis in various countries and categorizes the countries in terms of how their urolithiasis incidence rate has changed over time.MethodsThe incidence rate of urolithiasis in 204 countries from 1990 to 2019, extracted from the Global Burden of Disease study, has been analyzed.ResultsAccording to the results, all regions had experienced an increasing trend in urolithiasis rate, except for Eastern Europe, Central Europe, and Southeast Asia regions (decreasing rates of -71.4, -56.2, and -9.2 per 100000, respectively). Moreover, the Caribbean region had the highest increasing trend of urolithiasis rates, and Central Asia was in the next rank (increasing rate of 48.3 and 34.3 per 100,000, respectively, p-value < .05). Also, African regions revealed significant increasing trends over time (p-value < 0.05). The outstanding findings in cluster analysis showed that Afghanistan, Andorra, and Comoros had the most decreasing trend in urolithiasis rates over time (decreasing rate of -128.2 per 100000, p-value < .001). Cuba, Cyprus, Czechia, the Democratic People's Republic of Korea, Denmark, and Djibouti were in the next rank in terms of decreasing rate (decreasing rate of -92.3 per 100000, p-value < .001). In addition, urolithiasis rates in Congo, Eswatini, Gabon, and Grenada have the most increasing trend (increasing rate of 116.1 per 100000, p-value < .001).ConclusionThe trend of urolithiasis rates was significantly increased in most countries, and Congo, Eswatini, Gabon, and Grenada had the highest trend among others. Also, Afghanistan, Andorra, and Comoros revealed the most decreasing rates, and the trend has dropped remarkably in several other countries.

Global, Regional, and National Incidence and Disability-Adjusted Life-Years for Urolithiasis in 195 Countries and Territories, 1990-2019: Results from the Global Burden of Disease Study 2019.

Purpose: Urolithiasis is highly prevalent worldwide. The aim of this study was to report the results of the Global Burden of Disease 2019 study on urolithiasis burden estimates grouped by gender, regions, countries or territories, and sociodemographic index (SDI) from 1990 to 2019 globally. Methods: We reported detailed estimates and temporal trends of the burden estimates of urolithiasis from 1990 to 2019 in 195 countries and territories and further evaluated the relationship between these estimates and SDI, a composite indicator of income per person, years of education, and fertility as a measurement of country/region socio-economic level. Urolithiasis incidence and disability-adjusted life years by gender, regions, countries or territories, and SDI were reported. The percentage change and estimated annual percentage change of these burden estimates were calculated to quantify temporal trends. Results: From 1990 to 2019, the age-standardized incidence rate (ASIR) and disability-adjusted life years (DALYs) of urolithiasis decreased globally by 0.459% and 1.898% per year, respectively. Such a trend of ASIR was prominently due to the decline in the middle, high-middle, and high SDI countries, including Eastern Asia, high-income Eastern Europe, and high-income North America. During this period, these estimates increased in low and low-middle SDI countries, particularly in South Asia, Andean Latin America, and Western Europe. A decline in DALYs was observed in all SDI countries. An approximate positive linear association existed between the burden estimate's decreased APC and SDI level, except at the high SDI level. Both males and females showed the same trend. Conclusions: This study provides comprehensive knowledge of the burden estimate of urolithiasis. Although the burden estimates of urolithiasis showed a global decrease during the past 29 years, this progress has yet to be universal; the increasing trends were observed in countries with low and low-middle SDI countries. Research in these countries is needed and helps with the appropriate allocation of health resources for prevention, screening, and treatment strategies.

EFFECT OF IRON ON BONE TISSUE METABOLISM AND THYROID FUNCTION IN CHILDREN LIVING ON RADIOLOGICALLY CONTAMINATED TERRITORIES SINCE THE ChNPP ACCIDENT.

identification of clinical and metabolic characteristics of osteogenesis and factors affecting bone mineral density (BMD) in children living in radioactively contaminated territories (RCT) after the ChNPP accident for the use of therapeutic and preventive measures aiming to reduce the incidence of disorders. Children aged 4 to 18 years old (n = 539) were involved in the study within 4 age groups, namely under 7 years old, 7-10 years old, 10-14 years old, older than 14 years old. Studied parameters in children with a reduced BMD (85-65 relative units and under 65 relative units) were estimated vs. the normative BMD (100-85 relative units) cases. Diagnosis of osteopenia and osteoporosis in children was established according to the BMD T-index. Family history of the relatives of children was studied. Body weight at birth, fractures of the long bones, complaints of osalgia, jaw anomalies, dental caries, presence of obesity, and hypermobility syndrome (HMS) were assessed. Peripheral blood biochemical tests were performed featuring the serum total protein, alkaline phosphatase (APh), calcium, vitamin D, creatinine, serum iron (SI), ferritin, cortisol, pituitary thyroid-stimulating hormone (TSH), and free thyroxine (FT4) assay. BMD was measured and radiation doses in children were reconstructed. BMD depended on the age of children. A direct correlation was established between the cholelithiasis and urolithiasis incidence (р < 0.01), cancer and endocrine diseases (р < 0.05) in the relatives of children that had BMD under 65 relative units. Dental caries developed more often (р < 0.05), while obesity was less frequent (р < 0.05) in the subjects with BMD < 65 relative units. A direct correlation was established between the level of serum creatinine and BMD (р < 0.01), and there was an inverse correlation between the serum APh level and BMD (р < 0.001).Every third child had a vitamin D deficiency. Fractures of long bones and increased content of SI and TSH were characteristic for the children having got osteopenia (BMD within 85-65 relative units), while besides a predisposition to bone fractures the higher levels of SI, APh, cortisol both with calcium deficiency were found in children with osteoporosis (BMD < 65 relative units) compared to the general group with a similar BMD. An increased incidence of HMS was characteristic too. Radiation doses in children with osteopenia were higher than in those with osteoporosis: (1.17 ± 0.09) mSv and (0.92 ± 0.06) mSv respectively (р < 0.05). No correlation was found between the radiation doses and clinical signs, blood biochemistry or BMD. Study of the functional mechanisms of bone structures in children, depending on their metabolism, had made it possible to reveal the factors that affect bone formation in children living in RCT after the ChNPP accident, and to form the population groups for the timely application of therapeutic and preventive measures aiming to reduce the incidence of disorders of musculoskeletal system.

Заболеваемость мочекаменной болезнью в Российской Федерации с 2005 по 2020 гг.

Introduction. Urolithiasis is a polyetiological, polypathognomonic metabolic disease characterized by the formation of kidney stones. The study of trends in the urolithiasis prevalence is of fundamental importance in practical medicine. The study of endemic territories allows us to analyze all possible risk factors for the development of urolithiasis from genetic to nutritional. The aim of our study is a comparative analysis of the urolithiasis prevalence in the Russian Federation for different periods. Materials and methods. We analyzed urolithiasis prevalence and incidence in the entire population of Russia from 2005 to 2020. The work is based on official statistics of the Ministry of Health of the Russian Federation. Statistical analysis of the data was carried out using the SPSS Statistics 21 software package. Results and discussion. Urolithiasis prevalence in the Russian Federation is considered in detail from 2005 to 2020. We did a comparative analysis of the data on the general urolithiasis prevalence, the incidence of urolithiasis, urolithiasis prevalence separately in the adult and children's population of Russia in the period from 2005 to 2020 out. We gave the leading regions in the Russian Federation in terms of the number of urolithiasis cases. We spent correlation analysis of the urolithiasis incidence with the number of cases of diabetes mellitus type 2, obesity and the level of meat consumption in the Russian population. Conclusion. Urolithiasis incidence and prevalence among the adult population is steadily growing in all regions of the Russian Federation, while the incidence among children remains stable. The relationship between the prevalence of urolithiasis and incidence of diabetes mellitus type 2 and obesity was noted.

MP37-08 RENAL TRANSPLANT UROLITHIASIS MANAGEMENT: A SYSTEMATIC REVIEW

You have accessJournal of UrologyRenal Transplantation & Vascular Surgery I (MP37)1 Sep 2021MP37-08 RENAL TRANSPLANT UROLITHIASIS MANAGEMENT: A SYSTEMATIC REVIEW Krishna Ravivarapu, Alexander Small, Nir Tomer, Evan Garden, and Michael Palese Krishna RavivarapuKrishna Ravivarapu More articles by this author , Alexander SmallAlexander Small More articles by this author , Nir TomerNir Tomer More articles by this author , Evan GardenEvan Garden More articles by this author , and Michael PaleseMichael Palese More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002046.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Renal transplant urolithiasis is an uncommon but serious issue. Management of these stones is challenging due to the urgency of an obstructed solitary kidney plus technical issues accessing a transplant. Treatments include observation, extracorporeal lithotripsy (ESWL), ureteroscopy (URS), percutaneous nephrolithotomy (PNL), and open surgical pyelotomy. There are currently no established guidelines for the management of transplant stones and comparative effectiveness research is lacking. We performed a critical systematic review of contemporary research to evaluate practice patterns and stone-free rates (SFR) among the interventions. METHODS: A systematic review was conducted for all English-language abstracts and peer-reviewed articles using the Pubmed, MEDLINE, Scopus, and Google Scholar databases from January 2010 to January 2020. Case-reports were excluded from analysis. Two authors independently extracted data on stone location, size, treatment approach, and SFR. RESULTS: 835 publications were screened and 11 were included in this analysis, with a total of 268 renal transplant urolithiasis patients. In 15,624 total transplants, overall urolithiasis incidence was 1.1% (0.4-2.4%). Average stone size was reported in 6 studies and was 12.2 mm (7.4-19.9 mm). Stones were identified in the kidney (51.7%) and ureter (48.3%). Primary treatments included ESWL 27.2%, URS 25.0%, PNL 13.4%, and open pyelotomy 4.5% with SFR 64.1% (0-100%), 87.1% (60-100%), 91.9% (75-100%), and 90.9% (50-100%) respectively. The overall stone-free rate across all first line treatments was 79.1%. Secondary treatments were reported in 41 patients - the approaches were observation (53.7%), PNL (19.5%), URS (14.6%), open pyelotomy (9.8%), and ESWL (2.4%). CONCLUSIONS: Renal transplant urolithiasis poses unique challenges to both patients and providers. This review represents a contemporary snapshot of global treatment strategies and comparative effectiveness. The most common approaches are observation, ESWL and URS, however the most definitive strategies are PNL and open pyelotomy. Ultimately, the approach should be tailored to the individual patient depending on stone size, location, patient anatomy, and surgeon experience. Future prospective studies of renal transplant urolithiasis can shed light on specific risk factors for stone formation as well as optimal treatment protocols. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e648-e648 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Krishna Ravivarapu More articles by this author Alexander Small More articles by this author Nir Tomer More articles by this author Evan Garden More articles by this author Michael Palese More articles by this author Expand All Advertisement Loading ...

Temporal Trend of Urolithiasis Incidence in China: An Age-Period-Cohort Analysis.

PurposeUrolithiasis is one of the commonest disease of the urinary system. This study aimed to assess the long-term urolithiasis incidence trends in China between 1990 and 2019.Patients and MethodsThe incidence data of urolithiasis were extracted from Global Burden of Disease Study 2019, and an age–period–cohort framework was used to estimate the age, period, and cohort effects.ResultsWe found that the net drift was −2.72% (95% CI: −2.84% to −2.60%) per year for men and −2.14% (95% CI: −2.24% to −2.05%) per year for women, and except men in age group 0–4, the local drift values were below 0 in all age groups (P<0.05 for all) in both sexes during the period of 1990 to 2019. In the same birth cohort, the risk of incidence from urolithiasis rose first and then decreased with age for both sexes after controlling for period deviations, and in addition, after 20 years old, the risk of incidence of urolithiasis in men was higher than that in women (significantly with P<0.05). In general, the estimated period and cohort relative risks were found in similar downward patterns for both sexes.ConclusionIn the past 30 years, the age-standard incidence of urolithiasis in both sex of Chinese people has decreased, but the crude incidence of urolithiasis in Chinese women has increased. Considering the aging of population structure in China, the overall number of female urolithiasis patients may increase, contributes to higher crude incidence rate. The problem of urolithiasis in Chinese women needs to be paid more attention.

The effect of urine acidification on calcium oxalate relative supersaturation in cats.

There is an apparent reciprocal relationship between magnesium ammonium phosphate (MAP, struvite) and calcium oxalate (CaOx) urolithiasis incidence rate in cats. The number of struvite uroliths submitted for analysis over the past 35 years has been decreasing, with an increase in CaOx urolith submissions. Commercial diets aimed to dissolve struvite uroliths are typically acidified, and it has been suggested that dietary acidification increases urinary calcium excretion and the risk of CaOx crystallization. The objective of this study was to assess the effect of urine acidification on the relative supersaturation (RSS) of CaOx in cats, as a representation of crystallization risk. Four diets were extruded to contain identical nutrient contents, but with gradual acidification (0, 0.6, 1.3 and 1.9% sodium bisulphate substituted sodium chloride in diets A, B, C and D respectively). Thirteen adult cats were fed each diet sequentially for a minimum of 10 days. Average urine pH was 6.4, 6.2, 6.0 and 5.9 on diets A, B, C and D respectively (p < 0.0001). Struvite RSS decreased on diets inducing more acidic urine pH (p < 0.0001). Urinary calcium excretion and concentration increased with diets inducing lower urine pH (p < 0.0001), but oxalate excretion and concentration decreased (p < 0.001). CaOx RSS was not different between diets (p = 0.63). These results suggest that a lower diet base excess and resulting urine pH to support struvite dissolution do not increase the risk for CaOx crystallization in the range of urine pH representative of most commercial feline diets. Long‐term studies are needed to confirm this.

The impact of ambient temperature on the incidence of urolithiasis: a systematic review and meta-analysis.

Objective This review aimed to confirm the association between ambient temperature and incidence of urolithiasis and evaluate the impact thereof. Methods A systematic literature review was performed up to September 2019 using multiple databases. The effect of temperature on urolithiasis risk was assessed using risk ratio (RR). Pearson correlation coefficient (Pearson's r) was used to evaluate the linear association between ambient temperature and urolithiasis incidence. The non-linear association between climatic temperature and the urolithiasis incidence was also evaluated. Results Twenty-four studies related to the temperature and urolithiasis risk in 14 different countries or regions of five continent involving over 2.5 million cases were included in the meta-analysis. High climatic or workplace temperature was a significant risk factor of urolithiasis. The weighted correlation coefficient (Pearson's r) of monthly temperature and urolithiasis risk was 0.49 [95% confidence interval (CI) 0.40-0.57], a moderate correlation (0.4<r<0.6). According to non-linear models, as the daily temperature increases by 5 °C, the risk of urolithiasis will increase by 10% (95% CI 8-11%). Conclusion Both workplace and climatic temperatures are related to the incidence of urolithiasis. Public health intervention strategies need to be developed to prevent those in high-risk districts or occupations from being exposed to high ambient temperature.

PT046 - The analysis of urolithiasis incidence in the contralateral kidney of uninephrectomy patients

PT046 - The analysis of urolithiasis incidence in the contralateral kidney of uninephrectomy patients

Correlative Analysis Between Severity of Urolithiasis and Laboratory Parameters and Its Implication in Evaluation of the Probable Risk Profile

Background: Urolithiasis presents serious hazard which significantly elevates the cost of national health expenditure in almost every part of both the hemispheres. There is high risk of hospitalization with loss of valuable human resource and decreased productivity along with it. Risk factors still evade the exact etiology and search for optimal serum panel is still in its infancy. Urolithiasis incidence has gradually increased in last 3 decades which suggests that some constant metabolic and urinary parameters are implicated in the risk of occurrence of urinary stone. The present study is intended to identify a panel of serum parameters, urinary parameters, radiological characteristics and correlating it with the clinical severity of stone disease. Methods: The present study was conducted at the Department of Urology at GMCH Guwahati. The authors retrospectively analyzed 151 patients undergoing stone surgery from a period of January 2016 to August 2017. Data comprised of all serum and urinary examinations done 1 week preoperatively and radiological scans within 1 month before surgery. Spearman test was used to determine correlation and analysis of variance (ANOVA) was applied for comparison between more than two categories. Results: Stone multiplicity was positively correlated with upper tract stone sides (r = 0.530, P < 0.01), large stone volume (r = 0.172, P < 0.02), stone recurrence, urinary infection and urine protein. Upper tract stone sides number was positively correlated with upper tract obstruction sides (r = 0.542, P < 0.03), large stone volume (r = -0.321, P < 0.01). Upper tract obstruction sides number was positively correlated with large stone volume (r = -0.848, P < 0.01). Conclusions: Results demonstrated that urinary tract obstruction and total stone volume significantly correlated with abnormal serum panel, urinary profile and were harbinger of complex stone pattern. World J Nephrol Urol. 2018;7(1):25-31 doi: https://doi.org/10.14740/wjnu332w

The analysis of urolithiasis incidence in the contralateral kidney of unilateral nephrectomy patients

Objective To analyze the incidence of urinary stone formation in the contralateral kidney of unilateral nephrectomy patients. Methods 1048 patients, including 596 males and 452 females, underwent unilateral nephrectomy from June 2010 to June 2016. Their age ranged from 16-87 years old (mean 58.7 years old).532 patients combined with components of metabolic syndrome and 213 patients with metabolic syndrome.164 patients had a previous history of urolithiasis.The incidence of urinary stone formation in the contralateral kidney after nephrectomy was recorded and analyzed.The urolithiasis incidences in different gender, age, comorbidity and history of urolithiasis patients after uninephrectomy were compared. Results All patients were followed up within 0.5 to 6 years (mean 3.2 years). 89 patients suffered from urinary stones in the contralateral kidney after uninephrectomy.The incidence of urinary stone formation in the contralateral kidney was 8.5%(89/1048), which was higher than that in general population of China. 1%-5%.The urolithiasis incidence was 9.1%(54/596)in male patients and 7.7%(35/452)in female patients after nephrectomy. The incidence of urinary stone formation was 8.6%(3/35)in patients aged under 30 years old, 12.5%(34/272)in patients aged 30-49 years old, 7.3%(37/504)in patients aged 50-69 years old, 6.3%(15/237)in patients aged 70 and over.The incidence of urinary stone formation was 12.2%(65/532)in patients with components of metabolic syndrome after nephrectomy and 19.7%(42/213)in patients with metabolic syndrome, while the incidence was 4.7%(24/516)in patients without components of metabolic syndrome.In patients with history of urolithiasis, the incidence was up to 30.5%(50/164)after nephrectomy, while 4.4%(39/884)in patients without history of urolithiasis. Conclusions The incidence of urinary stone formation in the contralateral kidney of uninephrectomy patients was higher, especially in patients with metabolic syndrome or urolithiasis history.Patients after unilateral nephrectomy are more vulnerable to urolithiasis. Key words: Uninephrectomy; Urolithiasis; Incidence; Metabolic syndrome

The study of mineral composition and structure of uroliths in the residents of Tomsk district (Tomsk)

To successfully treat and prevent urolithiasis, the composition and structure of uroliths should be examined using modern analytical techniques. For a long time, studies of the biomineral formation in the human body have been conducted exclusively in the field of medicine. The main attention has been paid to the diagnosis and treatment of diseases leading to the occurrence of pathogenic formations. At the same time, it is quite obvious that it is important to have a clear idea about the causes of pathogenic formations, the mechanisms for their further formation, composition and structure. Currently, these issues are widely studied all over the world by mineralogists, biochemists, geo-ecologists using methods of mineralogical analysis. The aim of this work was to determine the content of the elements that make up uroliths. This value should be normalized by the clarks of the noosphere. Studies on the mineral composition and structure of uroliths in the Tomsk region allowed to calculate the content of elements. It turned out that each medical district has its own specific geochemical series, which depends, probably, on natural and technogenic factors. The study included urolith samples obtained from residents of 4 medical sub-districts of Tomsk district. 100 samples of different mineral composition were studied. Analytical techniques including crystal-morphological, spectral, X-ray structural, instrumental neutron-activation, electron microscopic analyses were used to investigate the morphology, mineral composition and structure of uroliths. The average content of elements in the uroliths, and the element concentrations normalized by the clark were established. After calculating the concentration, geochemical associative series of elements were formed. Depending on the morphology, drusiform, microspherolite, porous, coral formations, uroliths with a smoothed surface and stones with combined morphology were identified. Three groups of uroliths were defined according to their structural features: crystalline-granular, spherolithic and combined. Studies to determine the mineral composition and structure of the uroliths of the inhabitants of the Tomsk region made it possible to calculate the content of the elements that make up uroliths, normalized by clarks of the noosphere. Each medical sub-district has its own specific geochemical series, which depends on natural and technogenic factors. The increased value of the indicator of the content of elements in uroliths should serve as a warning factor for developing measures to reduce the urolithiasis incidence in the population.

Daily Mean Temperature and Urolithiasis Presentation in Six Cities in Korea: Time-Series Analysis.

Seasonal variation in urinary stone presentation is well described in the literature. However, previous studies have some limitations. To explore overall cumulative exposure-response and the heterogeneity in the relationships between daily meteorological factors and urolithiasis incidence in 6 major Korean cities, we analyzed data on 687,833 urolithiasis patients from 2009 to 2013 for 6 large cities in Korea: Seoul, Incheon, Daejeon, Gwangju, Daegu, and Busan. Using a time-series design and distributing lag nonlinear methods, we estimated the relative risk (RR) of mean daily urolithiasis incidence (MDUI) associated with mean daily meteorological factors, including the cumulative RR for a 20-day period. The estimated location-specific associations were then pooled using multivariate meta-regression models. A positive association was confirmed between MDUI and mean daily temperature (MDT), and a negative association was shown between MDUI and mean daily relative humidity (MDRH) in all cities. The lag effect was within 5 days. The multivariate Cochran Q test for heterogeneity at MDT was 12.35 (P = 0.136), and the related I2 statistic accounted for 35.2% of the variability. Additionally, the Cochran Q test for heterogeneity and I2 statistic at MDHR were 26.73 (P value = 0.148) and 24.7% of variability in the total group. Association was confirmed between daily temperature, relative humidity and urolithiasis incidence, and the differences in urolithiasis incidence might have been partially attributable to the different frequencies and the ranges in temperature and humidity between cities in Korea.

Factors Affecting Complication Rates of Percutaneous Nephrolithotomy in Children: Results of a Multi-Institutional Retrospective Analysis by the Turkish Pediatric Urology Society

We assessed factors affecting complication rates of percutaneous nephrolithotomy in children. We retrospectively evaluated data on 1,205 renal units in 1,157 children treated with percutaneous nephrolithotomy at 16 Turkish centers between 1991 and 2012. Of the patients 28.3% had a history of urolithiasis. Complications were evaluated according to the Satava classification system and modified Clavien grading system. Univariate and multivariate analyses were done to determine predictive factors affecting complication rates. A total of 515 females and 642 males were studied. Mean ± SD patient age was 8.8 ± 4.7 years (range 4 months to 17 years). Mean ± SD stone size, operative time and postoperative hospital stay were 4.09 ± 4.06 cm(2), 93.5 ± 48.6 minutes and 5.1 ± 3.3 days, respectively. Postoperative stone-free rate was 81.6%. A total of 359 complications occurred in 334 renal units (27.7%). Complications were intraoperative in 118 cases and postoperative in 241. While univariate analysis revealed that stone history, positive urine culture, operative time, length of hospitalization, treatment success, punctured calyx and location of the stone significantly affected the complication rates (p <0.05), operative time, sheath size, mid calyceal puncture and partial staghorn formation were the statistically significant parameters affecting complication rates on multivariate logistic regression analysis. Percutaneous nephrolithotomy is the treatment of choice for most renal calculi in children. The technique is effective and safe in children, with a high success rate and a low rate of major complications. The significant factors identified should be considered by clinicians to decrease associated complication rates.

Urolithiasis associated with atazanavir may mask a metabolic 'channelling' bias

Sir, Chronic kidney disease (CKD) is an emerging clinical issue in HIV, particularly in ageing infected patients. Nephrotoxicity is a major issue and a frequent cause of drug switching owing to glomerular or tubular damage and the fear of progressive CKD.However, the incidence and impact of urolithiasis as an independent contributor to CKD are not known in HIV-infected patients. Historically, antiretroviral-induced urolithiasis has been common inpatientstreatedwith indinavir,probablyduetodrugcrystallization and precipitation in the kidneys. At present, with regards to the risk of urolithiasis, the use of boosted or unboosted atazanavir as preferred protease inhibitor (PI) is of concern. In a large retrospective studyof 1240 HIV-infected individuals, Hamada et al. reported a urolithiasis incidence of 23.7 cases per 1000 patient-years among atazanavir-treated patients. Notably, the authors postulated that atazanavir/ritonavir can promote kidney stones via similar mechanisms to indinavir-induced urolithiasis. This single-centre study, as the authors pointed out, had several limitations owing to its observational and retrospective nature and because of the absence of renal stone composition analyses. In particular, the hypothesized pathogenetic mechanism – atazanavir-supersaturated urine inducing crystalluria – is difficult to test in consideration of the lack of association between serum bilirubin levels, surrogate markers of plasma atazanavir concentration and the risk of kidney stones. By contrast, baseline data showed significantly higher uric acid concentrations in patients treated with atazanavir/ritonavir compared with patients treated with other PIs. Even though uric acid levels did not affect the Cox proportional hazard regression model results, and atazanavir/ritonavir exposure was associated with a 10-fold increased risk for kidney stones, these results may have been distorted by a ‘channelling’ bias. Atazanavir/ritonavir is preferentially prescribed to patients with higher metabolic risk profiles (European AIDS Clinical Society; Version 6.1; November 2012; http:// www.europeanaidsclinicalsociety.org/index.php?option1⁄4com_con tent&view1⁄4article&id1⁄459&Itemid=41). An expanding body of evidence supports the notion that kidney stones are not always a separate entity but in some instances represent an epiphenomenon of a systemic metabolic disorder, being associated with insulin resistance and metabolic syndrome.In keeping with the study by Hamada et al., it is plausible that at least some of the reported effects of atazanavir/ritonavir could be confounded by physician prescription. Interestingly, the prevalence of nephrolithiasis seems higher among HIV-infected individuals than the general population (0.8%). Raheem et al. described 46 cases of nephrolithiasis in a cohort of 436 HIV-positive subjects, corresponding to an overall 11% prevalence: similar to what is expected in the general population. Unfortunately, stone analysis was only available in seven subjects and documented four cases of calcium oxalate monohydrate crystals and only one case each of cystine, uric acid and atazanavir crystals. A similar prevalence of kidney stones was described in the Castle study, the largest randomized clinical trial on atazanavir/ritonavir ever performed in naive patients. Though evidence in HIV-infected individuals is far from being conclusive, the study by Hamada et al. suggests a thorough metabolic evaluation for nephrolithiasis in HIV-infected patients with recurrent episodes of kidneystones, a family historyof nephrolithiasis or evidence of multiple kidney stones at imaging. However, we suggest caution in interpreting the epidemiological data linking atazanavir exposure and kidney stones owing to a potential ‘channelling’ bias. Indeed, an excess number of patients with metabolic disturbance may be prescribed the atazanavir/ritonavir regimen in light of its favourable lipid profile, but these patients are in fact at higher risk for urolithiasis. This situation significantly resembles our observation regarding the spurious association between abacavir and cardiovascular disease, which in fact was mediated by CKD, which was in turn the comorbidity that prompted healthcare workers to prefer abacavir to tenofovir. New observational studies and randomized clinical trials are needed to prove this hypothesis.

The association between the incidence of urolithiasis and nutrition based on Japanese National Health and Nutrition Surveys

To clarify the association between regional variations in urolithiasis incidence and nutrition intake, we evaluated associated data from Japanese national surveys. The incidence of urolithiasis in 12 regions of Japan was calculated from 2005 patient data obtained from 430 hospitals (n=92,797). Nutrition intake data were obtained from the National Health and Nutrition Survey. We examined the association between urolithiasis incidence and average intake of various types of food or nutrients by region. Continuing surveys in Japan reveal fixed variations in urolithiasis incidence among geographic regions. The national average of patients with urolithiasis was estimated as 203.1 per 100,000 citizens. Regarding food, intake of fruit correlated negatively with the incidence of urolithiasis (r=-0.721, p=0.008), while intake of eggs (r=0.537, p=0.072) and sugar (r=0.475, p=0.119) tended to positively correlate with incidence. Regarding nutrients, intake of potassium (r=-0.500, p=0.098), vitamin K (r=-0.562, p=0.057), and pantothenic acid (r=-0.560, p=0.058) tended to negatively correlate with incidence. The incidence of urolithiasis is higher in geographic areas with populations having low fruit and high sugar intake.

Urolithiasis in a Rural Wisconsin Population From 1992 to 2008: Narrowing of the Male-to-Female Ratio

Urolithiasis is a common disease with multiple etiologies and risk factors. Studies suggest an increased incidence in developed nations in recent decades as well as differential geographic incidence and prevalence rates, and differences between the genders. We updated urolithiasis epidemiological data by examining the incidence and prevalence rates in a stable rural Wisconsin population. Data were obtained from the Marshfield Epidemiologic Study Area database, a surveillance tool created in 1991 to track disease in residents of an area of 24 ZIP Codes including approximately 85,000 individuals, of whom most receive care at Marshfield Clinic and affiliates. Urolithiasis cases were identified using ICD-9 codes. Incidence, prevalence and recurrence rates were determined. The mean age adjusted incidence of new onset urolithiasis per 100,000 person-years was 202 (95% CL 168-235) in 1992 and 289 (95% CL 253-325) in 2008. In women the increase per 100,000 person-years was higher than in men, that is 171 (95% CL 129-213) and 289 (95% CL 238-340) vs 238 (95% CL 184-290) and 296 (95% CL 244-348), respectively. The male-to-female incidence ratio decreased from 1.4 to 1.0. The age adjusted prevalence per 100,000 individuals was 1,968 (2%) and 3,554 (3.5%) in 1992 and 2008, respectively. The increase in women was higher than in men (52% vs 26%). The age adjusted recurrence rate per 100,000 individuals was 553 (0.72%) and 676 (1.0%) in 1992 and 2008, respectively. The increase in women was higher than in men (88% vs 20%). Since 1992, urolithiasis incidence, prevalence and recurrence rates in this rural Wisconsin population have increased with higher increases noted in women. While prevalence increased, it was lower than reported in other geographic areas in the United States.