Seasonal variations in urinary calculi attacks and their association with climate: a population based study

The first epidemiology of urolithiasis in Northern Vietnam: Urinary stone composition, age, gender, season, and clinical features study

OBJECTIVES

The aim of this study is to analyze the compositions of urinary stones and investigate their distributions in different ages, genders, seasons, and clinical features of Northern Vietnamese patients.

METHODS

A total of 231 patients with urinary stones from Northern Vietnam were collected and analyzed composition from 1/2021-12/2022. For all patients, age, sex, stone location, stone side, urine pH, and hospitalized date (month) were collected.

RESULTS

Kidney stones are more frequently found in men than women with the male: female urinary stones ratio in this study being 1.96:1. The highest stone prevalence appeared between 60 and 69 years old. The most common stone composition was calcium oxalate, followed by calcium phosphate, uric acid, struvite, and cysteine. Mix stones of CaOx and CaP were more prevalent than pure stones. Males submitted more CaOx, CaP, and UA stones, whereas females were susceptible to infectious stones. Stones were more frequently found on the left side of the upper urinary tract (51.9%) than on the right side (27.3%) and lower urinary tract (7.8%). Cultural tendency leads to a smaller number of stones during the Lunar new year (February), and Ghost month (August).

Heat exposure and hospitalizations for chronic kidney disease in China: a nationwide time series study in 261 major Chinese cities

BACKGROUND

Climate change profoundly shapes the population health at the global scale. However, there was still insufficient and inconsistent evidence for the association between heat exposure and chronic kidney disease (CKD).

METHODS

In the present study, we studied the association of heat exposure with hospitalizations for cause-specific CKD using a national inpatient database in China during the study period of hot season from 2015 to 2018. Standard time-series regression models and random-effects meta-analysis were developed to estimate the city-specific and national averaged associations at a 7 lag-day span, respectively.

RESULTS

A total of 768,129 hospitalizations for CKD was recorded during the study period. The results showed that higher temperature was associated with elevated risk of hospitalizations for CKD, especially in sub-tropical cities. With a 1 °C increase in daily mean temperature, the cumulative relative risks (RR) over lag 0-7 d were 1.008 [95% confidence interval (CI) 1.003-1.012] for nationwide. The attributable fraction of CKD hospitalizations due to high temperatures was 5.50%. Stronger associations were observed among younger patients and those with obstructive nephropathy. Our study also found that exposure to heatwaves was associated with added risk of hospitalizations for CKD compared to non-heatwave days (RR = 1.116, 95% CI 1.069-1.166) above the effect of daily mean temperature.

CONCLUSIONS

Short-term heat exposure may increase the risk of hospitalization for CKD. Our findings provide insights into the health effects of climate change and suggest the necessity of guided protection strategies against the adverse effects of high temperatures.

The influence of climatic factors in the seasonal fluctuation of urolithiasis and the trend of stone disease management in the southern Taiwan

This study aims to analyze the effects of climate parameters on the number of urolithiasis treatments in our hospital and understand the effects of climate parameters on the prevalence of urolithiasis in southern Taiwan. We also look at trends associated with urolithiasis and treatments. Retrospectively reviewed the records of extracorporeal shockwave lithotripsy (ESWL), ureteroscopy (URS), retrograde intrarenal surgery (RIRS), and percutaneous nephrolithotripsy (PCNL) performed in our hospital from January 2012 to December 2018. Climate data for were collected from Central Weather Bureau. The monthly meteorological data included average temperatures, humidity, rainfall, sunshine hours, atmospheric pressure, and wind speed. Monthly numbers of patients undergoing stone management was positively correlated to average temperature (r = 0.657), relative humidity (r = 0.234), monthly rainfall (r = 0.261) and monthly sunshine hours (r = 0.348), while it was negatively correlated to atmospheric pressure (r = - 0.522). The multivariate linear regression model demonstrated temperature (ß = 10.682, 95% CI 6.178-14.646, p < 0.001) and Relative humidity (ß = - 95% CI - 5.233- - 1.216, p = 0.002) to be independently related to numbers of stone treatment. The data also revealed a rising prevalence of urolithiasis with an associated increase in the number of interventions, with fewer ESWL (74.0-49.4%). Temperature and relative humidity are associated with monthly numbers of stone treatment. Ambient temperature is the most critical climate factor affecting the prevalence of symptomatic urolithiasis and intention of active stone removal in southern Taiwan.

High ambient temperature increases the number of emergency visits for upper urolithiasis in Hefei City, China

Background

Few studies have examined the effect of ambient temperature on upper urolithiasis in developing countries, with even fewer considering individual factors.

Methods

The present study analyzed data on emergency department visits for upper urolithiasis from three hospital sites of a large hospital in Hefei, China, during 2016-2020. Data on environmental factors during the same period were also analyzed. A time series analysis employing a generalized Poisson regression model (GPRM) combined with a distributed lag non-linear model (DLNM) was conducted to evaluate the effect of ambient temperature on the number of emergency department visits for upper urolithiasis.

Results

We found that ambient temperatures above 9 °C were positively associated with the frequency of upper urolithiasis visits, with the relationship being most significant on the current day and with a one-day lag. In the single-day lag effect, the most significant relative risk (RR) for mild heat (75th percentile) and high heat (95th percentile) was 1.229 (95% CI: 1.100-1.373) and 1.337 (95% CI: 1.134-1.577), respectively. The cumulative lag effect was significantly higher than the single-day lag effect, with maximum relative risks (RRs) of 1.779 (95% CI: 1.356-2.335) and 2.498 (95% CI: 1.688-3.697), respectively. The maximum lag time was 7 days. RRs were also higher among women and individuals aged 30-44 years.

Conclusions

Increased ambient temperature is a risk factor for upper urolithiasis, and there is a hysteresis effect. Women and individuals aged 30-44 years are the most susceptible.

Association between daily temperature and hospital admissions for urolithiasis in Ganzhou, China: a time-series analysis

Urolithiasis was a global disease and it was more common in southern China. This study looked into the association between daily temperature and urolithiasis hospital admissions in Ganzhou, a large prefecture-level city in southern China. In Ganzhou City from 2016 to 2019, a total of 60,881 hospitalized cases for urolithiasis from 69 hospitals and meteorological data were gathered. The effect of high ambient temperature on urolithiasis hospital admissions was estimated using a distributed lag nonlinear model. Stratified analysis was done to examine sex differences. The study found that in Ganzhou of China, the exposure-response curves approximated a "J" shape which across genders were basically similar. The maximum lag effect occurred on the second day after high temperatures for males but on the third day for females. Compared to the 10 °C reference temperature and considering the cumulative lag effect of 10 days, the relative risks of the daily mean temperature at the 95th percentile on the total, male, and female hospital admissions for urolithiasis were 2.026 (95% CI: 1.628, 2.521), 2.041 (95% CI: 1.603, 2.598), and 2.030 (95% CI: 1.552, 2.655), respectively, but the relative risks between sex were not statistically significant (p = 0.977). Urolithiasis morbidity risk in China could be exacerbated by high temperatures. The effect of high temperature on urolithiasis was similar across genders.

Effects of ambient temperature on hospital admissions for obstructive nephropathy in Wuhan, China: A time-series analysis

Under the background of global warming, it has been confirmed that heat exposure has a huge impact on human health. The current study aimed to evaluate the effects of daily mean ambient temperature on hospital admissions for obstructive nephropathy (ON) at the population level. A total of 19,494 hospitalization cases for ON in Wuhan, China from January 1, 2015 to December 31, 2018 were extracted from a nationwide inpatient database in tertiary hospitals according to the International Classification of Diseases (ICD)- 10 codes. Daily ambient meteorological and pollution data during the same period were also collected. A quasi-Poisson Generalized Linear Model (GLM) combined with a distributed lag non-linear model (DLNM) was applied to analyze the lag-exposure-response relationship between daily mean temperature and daily hospital admissions for ON. Results showed that there were significantly positive associations between the daily mean temperature and ON hospital admissions. Relative to the minimum-risk temperature (-3.4 ℃), the risk of hospital admissions for ON at moderate hot temperature (25 ℃, 75th percentile) occurred from lag day 4 and stayed to lag day 12 (cumulative relative risk [RR] was 1.846, 95 % confidence interval [CI]: 1.135-3.005, over lag 0-12 days). Moreover, the risk of extreme hot temperature (32 ℃, 99th percentile) appeared immediately and lasted for 8 days (RR = 2.019, 95 % CI: 1.308-3.118, over lag 0-8 days). Subgroup analyses indicated that the middle-aged and elderly (≥45 years) patients might be more susceptible to the negative effects of high temperature, especially at moderate hot conditions. Our findings suggest that temperature may have a significant impact on the acute progression and onset of ON. Higher temperature is associated with increased risks of hospital admissions for ON, which indicates that early interventions should be taken in geographical settings with relatively high temperatures, particularly for the middle-aged and elderly.

Are there seasonal variations in renal colic in uric acid stone formers in Germany?

PURPOSE

Seasonal variations in renal colic have been described by many authors for different countries worldwide. In most studies, there was no differentiation with regard to stone composition. Recently, we demonstrated that there was no seasonal variation in renal colic and urine chemistry for calcium oxalate stone formers in Germany. As we have many uric acid stone formers (UASFs) in our region, we were interested in learning the situation of this type of stone.

METHODS

We studied 286 consecutive UASFs with symptoms of renal colic. We divided them into four groups according to the quarters of the year. For stone analysis, X-ray diffraction/polarizing microscopy was used. Additionally, the following general parameters were examined in all patients: age, BMI, blood pressure, stone frequency, diabetes mellitus; blood: creatinine, glucose, uric acid, calcium, sodium and potassium; urine: pH, volume, calcium, uric acid, citrate, ammonia, and urea. Using the statistical program Prism 5 (GraphPad Software, San Diego, USA), significant differences between the four groups were calculated by the Kruskal-Wallis test.

RESULTS

We observed significantly more UASFs with renal colic in the third and fourth quarters of the year. This is in contrast to our findings in calcium oxalate patients. However, there was no variation in metabolic parameters.

CONCLUSION

The reasons are unclear; different temperatures are not a sufficient explanation, as one quarter is in the warm season and the other one is in the cold season. Unfortunately, no data have been reported in the literature thus far. Further studies are required to better understand these findings.

Association between Temperature and Inpatient Stone Admission in a Pediatric Population

BACKGROUND

Higher temperatures have been associated with increased stone formation and subsequent utilization of hospital resources, including inpatient admission. However, these observations have been derived from the adult population. We sought to examine if this purported association extends to the pediatric population.

METHODS

We used the 2016 Kids' Inpatient Database to identify nationwide pediatric inpatient admissions related to nephrolithiasis. Temperature data from the National Oceanic and Atmospheric Administration was linked to each admission. Comparative statistics analyzed patient and admission characteristics. Multivariable logistic regression analyzed associations between stone-related admissions and temperature. As a frame of reference, this analysis was replicated using the National Inpatient Sample from 2016 to evaluate associations in the adult population.

RESULTS

Of the 2,496,257 pediatric admissions, 8,453 (0.33%) were related to nephrolithiasis. Temperatures at the time of stone admission were higher than those during non-stone admission (55.9°F vs. 54.8°F, P<0.001). The stone admission group had a higher proportion of females than the non-stone admission group (64.8% vs. 55.4%, P<0.001). Stone admission was significantly associated with temperature (OR 1.025 per 10°F, 95% CI 1.003-1.049, P=0.03) and female sex (OR 1.097, 95% CI 1.027-1.171, P=0.006). In the adult population, 380,520 out of 30,000,941 patients (1.3%) were admitted with a stone. The effect of temperature on stone admissions was similar to that in the pediatric population (OR 1.020, 95% CI 1.014-1.026, P<0.001), but women were over 20% less likely to be admitted for stones than men (OR 0.770, 95% CI 0.757-0.784, P<0.001).

CONCLUSIONS

Increased temperatures were associated with an increased risk of stone-related admission in both the pediatric and adult populations. Females were at increased risk for stone-related admissions during childhood, but this trend reverses in adulthood.

Do weather parameters affect the incidence of renal colic in a predominantly warm country? A multicenter study

Purpose:

To determine whether there is any effect of weather parameters on the incidence of renal colic patients presenting to emergency rooms (ERs) during the hottest season in Israel.

Materials and Methods:

This retrospective multicenter study involved all ER admissions related to renal colic in nine centres throughout Israel between 2010 and 2017. The collected data included the date of ER visits, the patients’ age and sex, and the weather features of ambient temperature, wind velocity, noon heat index, and barometric pressure. Multivariable logistic regression analyses identified predictors of increased ER visits for renal colic.

Results:

There were 85,501 renal colic-related ER visits during the study period, involving 62,935 (74%) males and 22,566 (26%) females ( p < 0.005). The mean ± standard deviation (SD) age of the males and females was 50 ± 5.8 and 48 ± 19.6 years, respectively ( p = 0.1). Most of the ER arrivals were in the 31- to 50-year-old age group (37%, 31,508) ( p = 0.02). The maximal ambient temperature (odds ratio (OR) = 2.213, 95% confidence interval (CI) = 2.148–2.279, p < 0.0001), lower heat index (i.e. low humidity; OR = 0.880, 95% CI = 0.872–0.887, p < 0.0001) and increased wind velocity (OR = 1.165, 95% CI = 1.149–1.182, p < 0.0001) had a significant linear effect on ER visits for renal colic events.

Conclusion:

Conditions that increase sweat evaporation during the hottest months, including a decreased heat index and increased wind velocity, correlated with more ER visits for renal colic events, probably due to dehydration associated with elevated sweat evaporation.

Level of evidence:

Not applicable

Hot weather as a risk factor for kidney disease outcomes: A systematic review and meta-analysis of epidemiological evidence

BACKGROUND

The occurrence or exacerbation of kidney disease has been documented as a growing problem associated with hot weather. The implementation of effective prevention measures requires a better understanding of the risk factors that increase susceptibility. To fill gaps in knowledge, this study reviews the current literature on the effects of heat on kidney-disease outcomes (ICD-10 N00-N39), including morbidity and mortality.

METHODS

Databases were systematically searched for relevant literature published between 1990 and 2020 and the quality of evidence evaluated. We performed random effects meta-analysis to calculate the pooled relative risks (RRs) of the association between high temperatures (and heatwaves) and kidney disease outcomes. We further evaluated vulnerability concerning contextual population characteristics.

RESULTS

Of 2739 studies identified, 91 were reviewed and 82 of these studies met the criteria for inclusion in a meta-analysis. Findings showed that with a 1 °C increase in temperature, the risk of kidney-related morbidity increased by 1% (RR 1.010; 95% CI: 1.009-1.011), with the greatest risk for urolithiasis. Heatwaves were also associated with increased morbidity with a trend observed with heatwave intensity. During low-intensity heatwaves, there was an increase of 5.9% in morbidity, while during high-intensity heatwaves there was a 7.7% increase. There were greater RRs for males, people aged ≤64 years, and those living in temperate climate zones. Similarly, for every 1 °C temperature increase, there was a 3% (RR 1.031; 95% CI: 1.018-1.045) increase in the risk of kidney-related mortality, which also increased during heatwaves.

CONCLUSIONS

High temperatures (and heatwaves) are associated with an elevated risk of kidney disease outcomes, particularly urolithiasis. Preventive measures that may minimize risks in vulnerable individuals during hot spells are discussed.

Association of meteorological factors and ambient air pollution on medical care utilization for urolithiasis: a population-based time-series study

BACKGROUND

To identify the association of meteorological factors/ambient air pollutants with medical care utilization for urolithiasis and estimate the effect size/time lags.

METHODS

This is a population-based time-series analysis of 300,000 urolithiasis cases from eight large metropolitan areas in Korea. Seventeen meteorological factors and ambient air pollutants were measured daily during 2002-2017 for each metropolis. Data on daily medical utilization owing to urolithiasis were collected. A generalized additive model was used while factoring in the nonlinear relationship between meteorological factors/ambient air pollutants and urolithiasis and a time lag of ≤10 days. A multivariate analysis was performed. Backward elimination with an Akaike information criterion was used for fitting the multivariate model.

RESULTS

Urolithiasis was significantly associated with average temperature, diurnal temperature range, sunshine duration, particulate matter (PM) ≤2.5 μm, and carbon monoxide (CO) levels. The incidence of ureteral stones was positively correlated with average temperature, PM ≤2.5 μm level, and CO level (time lags 0-9, 2-4, and 0-9 days, respectively). The incidence of renal stones was positively correlated with PM ≤2.5 μm and CO levels (time lags 2-4 and 0-9 days, respectively). PM ≤2.5 μm (0.05 and 0.07% per 10 μg/m³⁾ and CO (2.05 and 2.25% per 0.1 ppm) conferred the highest excess risk on ureteral and renal stones.

CONCLUSIONS

Urolithiasis is affected by various meteorological factors and ambient air pollutants, PM ≤2.5 μm, and CO levels may be novel potential risk factors for this condition.

THE FUNCTIONAL STATE OF THE RENAL PARENCHYMA AFTER VARIOUS VIDEO ENDOSURGICAL METHODS OF TREATMENT OF PATIENTS WITH LARGE AND COMPLEX KIDNEY STONES

The work is based on the analysis of literature data devoted to the problem of preserving the functional state of the kidneys with various video endoscopic methods of surgical treatment of large and complex kidney stones. The purpose of the review is to highlight the likelihood of deterioration in the functional state of the kidneys in the postoperative period. A detailed analysis of postoperative outcomes in various minimally invasive methods of treatment of patients with large and complex kidney stones was carried out, with an overview of the possibility of using dynamic nephroscintigraphy as a method of objectively assessing the functional state of the kidneys.

Determining the true burden of kidney stone disease

The incidence and prevalence of kidney stones have increased over the past four decades. However, the diagnosis of 'kidney stone' can range from an incidental asymptomatic finding of limited clinical significance to multiple painful episodes of ureteral obstruction with eventual kidney failure. Some general strategies may be useful to prevent the recurrence of kidney stones. In particular, greater attention to kidney stone classification, approaches to assessing the risk of recurrence and individualized prevention strategies may improve the clinical care of stone formers. Although there have been some advances in approaches to predicting the recurrence of kidney stones, notable challenges remain. Studies of kidney stone prevalence, incidence and recurrence have reported inconsistent findings, in part because of the lack of a standardized stone classification system. A kidney stone classification system based on practical and clinically useful measures of stone disease may help to improve both the study and clinical care of stone formers. Any future kidney stone classification system should be aimed at distinguishing asymptomatic from symptomatic stones, clinically diagnosed symptomatic stone episodes from self-reported symptomatic stone episodes, symptomatic stone episodes that are confirmed from those that are suspected, symptomatic recurrence from radiographic recurrence (that is, with radiographic evidence of a new stone, stone growth or stone disappearance from presumed passage) and determine stone composition based on mutually exclusive categories.

The relationship of seasonality and the increase in urinary tract infections among hospitalized patients with spinal cord injury

BACKGROUND

Urinary tract infection (UTI) is the most frequent complication in patients who have spinal cord injury (SCI). The occurrence rate of UTI in this type of hospitalized patients was correlated to seasonality, age, and gender.

METHODS

Patients hospitalized during the 4-year study period with underlying SCI were identified from Taiwan's National Health Insurance Research Database. Patients with a discharge diagnosis of UTI were identified as those with SCI and UTI; they were divided into the following four age groups: <18 years, 18 to 44 years, 45 to 64 years, and ≥65 years. The gender, monthly number of cases, major complication rate, seasonal differences, and odds ratios (ORs) of associated factors were analyzed.

RESULTS

Data of 30 149 hospitalized patients diagnosed with SCI were retrieved. SCI and UTI were diagnosed in 3405 (11.3%) patients, of them 2296 were males (67.4%) and 1109 were females (32.6%). The UTI occurrence rate in hospitalized SCI patients was higher in males (11.8%) than in females (10.4%) (OR: 1.24; 95% CI: 1.15-1.34); it was highest in the ≥65-year-old age group (12.8%) and lowest in the <18-year-old age group (5.8%) (OR: 2.51; 95% CI: 1.83-3.44). The UTI occurrence rate varied from 7% to 18%, and it was highest in the summer (13.0% ± 2.6%) and lowest in the winter (10.2% ± 1.9%) (OR: 1.27; 95% CI: 1.15-1.40). Acute pyelonephritis was the most common complication in SCI and UTI cases.

CONCLUSION

The mean occurrence rate of UTI in hospitalized SCI patients was 11.3%; it was higher in males, in patients aged ≥65 years, and in the summer. Therefore, physicians should pay attention to the occurrence of UTI in aged male patients with SCI, especially in the summer.

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.

Comorbidity and socio-demographic factors associated with renal lithiasis in persons aged 40 to 65: A cross-sectional study

BACKGROUND AND OBJECTIVE

Renal lithiasis is one of the most important urological diseases. It seems to be related to different socio-demographic and climatic factors, lifestyle and pre-existing comorbidity. The aim of this study was to examine the relationship between socio-demographic variables, certain risk factors and chronic diseases and the renal lithiasis.

PATIENTS AND METHOD

A cross-sectional population-based study was carried out, selecting the Spanish population aged from 40 to 65 years, combining 2 random samples (PreLiRenA and PreLiRenE studies). Data were collected by personal telephone surveys, gathering information on socio-demographic variables and perceived morbidity. Data on annual average temperatures in each Spanish region were also collected. A bivariate and multivariate analysis was performed.

RESULTS

A total of 4,894 subjects were surveyed; 51.3% were women; 25% were aged 40-45 years, 36% had primary school education and 31.4% were of low social class. The overall prevalence of renal lithiasis was 15.0% (95% confidence interval [95% CI] 14.5-15.5). By means of multivariate analysis, the variables that showed a strong statistical relationship with the presence of renal lithiasis were: older age (61-65 years; OR=1.39; 95% CI 1.06-1.80), high social class (OR=1.98; 95% CI 1.29-2.62), family history of renal lithiasis (OR=2.22; 95% CI 1.88-2.65), high blood pressure (OR=1.68; 95% CI 1.39-2.02) and overweight/obesity (OR=1.31; 95% CI 1.12-1.54). A correlation was observed between renal lithiasis and average annual temperatures in the Spanish regions (r=0.59; P=.013).

CONCLUSIONS

A relationship was observed between renal lithiasis and older age, belonging to higher social classes, the existence of a family history of urolithiasis, and hypertension and overweight or obesity. The prevalence of renal lithiasis is greater in warmer climate zones.

Occupational Heat Stress and Kidney Health: From Farms to Factories

Millions of workers around the world are exposed to high temperatures, intense physical activity, and lax labor practices that do not allow for sufficient rehydration breaks. The extent and consequences of heat exposure in different occupational settings, countries, and cultural contexts is not well studied. We conducted an in-depth review to examine the known effects of occupational heat stress on the kidney. We also examined methods of heat-stress assessment, strategies for prevention and mitigation, and the economic consequences of occupational heat stress. Our descriptive review summarizes emerging evidence that extreme occupational heat stress combined with chronic dehydration may contribute to the development of CKD and ultimately kidney failure. Rising global temperatures, coupled with decreasing access to clean drinking water, may exacerbate the effects of heat exposure in both outdoor and indoor workers who are exposed to chronic heat stress and recurrent dehydration. These changes create an urgent need for health researchers and industry to identify work practices that contribute to heat-stress nephropathy, and to test targeted, robust prevention and mitigation strategies. Preventing occupational heat stress presents a great challenge for a concerted multidisciplinary effort from employers, health authorities, engineers, researchers, and governments.

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.

Worldwide Impact of Warmer Seasons on the Incidence of Renal Colic and Kidney Stone Disease: Evidence from a Systematic Review of Literature

INTRODUCTION

Several studies have examined the link between temperature or monthly seasonal variations and urolithiasis. The majority of these studies have demonstrated a link between higher ambient monthly temperatures and the incidence of renal colic and kidney stone disease (KSD). However, a worldwide trend on this association has not been explored and we perform a systematic review to examine the effect of seasonal variations on renal colic and KSD.

MATERIALS AND METHODS

A systematic review of the literature for a 26-year period (1990-2017) was conducted on all studies reporting on the effect of seasonal variations and its link to KSD. Two reviewers independently extracted the data from each study, which were analyzed using SPSS version 24.

RESULTS

A total of 59 studies were identified, and after screening, 13 were included in this review. The studies ranged in duration from 1 to 9 years (mean: 5.5 years) and included seasonal/monthly variations for proven stones or lithotripsy treatments or emergency department presentations with renal colic. Except for one study, there was a statistically significant association between higher monthly mean temperatures and the incidence of KSD-related events reported from the United Kingdom, South Korea, the United States, Saudi Arabia, Italy, Spain, Taiwan, Japan, and New Zealand.

CONCLUSIONS

Worldwide trends on the incidence of renal colic and KSD seem be affected by seasonal variation favoring warmer months, with data suggesting that higher ambient temperature has an association with KSD.

Epidemiology of stone disease across the world

Nephrolithiasis is a highly prevalent disease worldwide with rates ranging from 7 to 13% in North America, 5-9% in Europe, and 1-5% in Asia. Due to high rates of new and recurrent stones, management of stones is expensive and the disease has a high level of acute and chronic morbidity. The goal of this study is to review the epidemiology of stone disease in order to improve patient care. A review of the literature was conducted through a search on Pubmed^®, Medline^®, and Google Scholar^®. This review was presented and peer-reviewed at the 3rd International Consultation on Stone Disease during the 2014 Société Internationale d'Urologie Congress in Glasgow. It represents an update of the 2008 consensus document based on expert opinion of the most relevant studies. There has been a rising incidence in stone disease throughout the world with a narrowing of the gender gap. Increased stone prevalence has been attributed to population growth and increases in obesity and diabetes. General dietary recommendations of increased fluid, decreased salt, and moderate intake of protein have not changed. However, specific recommended values have either changed or are more frequently reported. Geography and environment influenced the likelihood of stone disease and more information is needed regarding stone disease in a large portion of the world including Asia and Africa. Randomized controlled studies are lacking but are necessary to improve recommendations regarding diet and fluid intake. Understanding the impact of associated conditions that are rapidly increasing will improve the prevention of stone disease.

The Risk of Nephrolithiasis Among Patients With Ankylosing Spondylitis: a Population-Based Cohort Study

Objectives

This study aims to investigate the correlation of ankylosing spondylitis (AS) with nephrolithiasis by performing a nationwide population- based cohort study.

Patients and methods

The data used in this retrospective cohort study were collected from the Taiwan National Health Insurance Research database. The study included a total of 3,334 AS patients (1,914 males, 1,420 females; mean age 44.51±16.83 years; range 22 to 79 years) and 13,336 non-AS patients (7,656 males, 5,680 females; mean age 44.27±17.01 years; range 21 to 78 years) who had been followed-up on an average of 6.78 years and 6.75 years, respectively, between January 2000 and December 2008.

Results

The percentage of newly diagnosed nephrolithiasis was 4.8% in all study subjects. However, the percentages of newly diagnosed nephrolithiasis were 5.76% and 4.58% in the AS and non-AS cohorts, respectively. After adjusting the patients' sex, age, urbanization level, and comorbidities, the hazard ratio obtained from our multivariable Cox model was 1.19.

Conclusion

Our study findings indicate that patients with AS are more likely to develop nephrolithiasis than non-AS patients.

Daily ambient temperature and renal colic incidence in Guangzhou, China: a time-series analysis

Few previous studies have examined the association between temperature and renal colic in developing regions, especially in China, the largest developing country in the world. We collected daily emergency ambulance dispatches (EADs) for renal colic from Guangzhou Emergency Center from 1 January 2008 to 31 December 2012. We used a distributed-lag nonlinear model in addition to the over-dispersed generalized additive model to investigate the association between daily ambient temperature and renal colic incidence after controlling for seasonality, humidity, public holidays, and day of the week. We identified 3158 EADs for renal colic during the study period. This exposure-response curve was almost flat when the temperature was low and moderate and elevated when the temperature increased over 21 °C. For heat-related effects, the significant risk occurred on the concurrent day and diminished until lag day 7. The cumulative relative risk of hot temperatures (90th percentile) and extremely hot temperatures (99th percentile) over lag days 0-7 was 1.92 (95 % confidence interval, 1.21, 3.05) and 2.45 (95 % confidence interval, 1.50, 3.99) compared with the reference temperature of 21 °C. This time-series analysis in Guangzhou, China, suggested a nonlinear and lagged association between high outdoor temperatures and daily EADs for renal colic. Our findings might have important public health significance to prevent renal colic.

Nephrolithiasis, stone composition, meteorology, and seasons in Malta: Is there any connection?

CONTEXT

The effect of seasons and meteorology on the incidence of nephrolithiasis has been studied in various regions around the globe, but seldom in the Mediterranean.

AIMS

This retrospective analysis aims at investigating these putative effects in the Maltese Islands, whose climate is typically Mediterranean, followed by a systematic review of the literature.

MATERIALS AND METHODS

Submission rate and chemical composition of all kidney stones after spontaneous passage or surgical removal between January 2009 and December 2011 were analyzed according to seasons and corresponding meteorology.

RESULTS

A total of 389 stones were analyzed. A higher stone submission rate was observed in summer compared to winter (31.6% vs. 20.8%, P = 0.0008) and in the warm period compared to the cold period (57.1% vs. 42.9%, P = 0.0001). Significant correlation was established between the monthly number of stones and mean monthly maximum temperature (r = 0.50, P = 0.002), mean monthly temperature (r = 0.49, P = 0.003) and mean monthly Humidex (r = 0.49, P = 0.007). Humidex was found to be an independent predictor for stone submission (β = 0.49, P = 0.007). The majority of stones contained calcium (83.3%), combined with oxalate (77.6%), phosphate (14.7%), and carbonate (2.8%). Some stones (11.8%) contained a mixture of >1 negatively charged molecules. Urate (11.6%), cysteine (4.6%), and ammonium-magnesium-phosphate (0.5%) constituted the rest. There was no association between chemical composition and seasons. Literature review included 25 articles. Higher ambient temperature and warm seasons were the most commonly encountered risk factors for both presentation and etiology of nephrolithiasis.

CONCLUSIONS

A significant positive correlation was noted between ambient temperature and stone submission rate, which was significantly higher during the warm months in Malta.

Clinical relevance of seasonal changes in the prevalence of ureterolithiasis in the diagnosis of renal colic

Ureterolithiasis is one of the most frequently diagnosed urologic diseases worldwide. Its annual incidence in Japan increased three-fold from 1965 to 2005. Ureterolithiasis incidence is affected by numerous factors, including race, sex, body weight, fluid intake, and climate. Here, we aimed to address the latter by considering the effect of seasonal variation on stone incidence and incorporating this information into a predictive model for differential diagnosis of ureteral stone from other conditions with similar presentations. We retrospectively identified 491 patients in our emergency department computer database who complained of back, flank, or lower abdominal pain during 2007-2015. Among them, 358 had stones, as confirmed by computerized tomography or plain abdominal X-ray of kidney-ureter-bladder. We also charted the mean ambient temperatures in our city for a year. The cases of ureteral stones paralleled the ambient temperatures, peaking during the hottest weather. Univariate analysis identified 13 factors associated with ureteral stones. Multivariate analysis narrowed the number to eight: age <60 years, male sex, short duration of pain (<6 h), nausea/vomiting, hydronephrosis, hematuria, history of urinary stone(s), and summer (July-September in Japan). Pain appearing during summer was nine times more likely to be due to a ureteral stone than was pain appearing during other seasons. We incorporated the eight variables identified into a predictive logistic regression model, which yielded good prediction of ureteral stones. Awareness that hot weather is associated with increased incidence of ureterolithiasis could facilitate differential diagnosis, and our prediction model could be useful for screening for ureterolithiasis.

The influence of environmental conditions on the incidence of renal colic in Rome

INTRODUCTION

The aim of this study was to investigate the effect of three major environmental variables (temperature, humidity, air pressure) on the probability of onset of renal colic (RC) in a large cohort of patients in Rome.

METHODS

The records of 2682 patients discharged by the Emergency Department (ED) of the University Hospital of Tor Vergata, Rome, from January 2007 to November 2009 with the main diagnosis of reno-ureteric colic associated with a proven calculus, were retrospectively evaluated. The climatic parameters (average humidity, average air pressure and daily minimum, medium and maximum temperature) were recorded in a second, independent database. RC events were grouped by weeks and months and analysed for a total period of 35 months and 153 weeks.

RESULTS

Two thousand five hundred and fourteen patients out of 2682 had a proven urolithiasis. RC events were observed more likely in the warmer months, from the second half of June to the first half of September, compared with the colder months. Although the weekly model showed a positive correlation (R2 = 0.134) between the average increase of environmental temperature and RC incidence, the monthly model was much more convincing (R2 = 0.373). We found no statistically significant correlation between humidity and air pressure and the incidence of RC.

CONCLUSIONS

This study demonstrates that an increase in average environmental temperature is associated with a significant increase in the number of episodes of RC seen in the ED at both weekly and monthly time intervals. The average humidity and air pressure were not found to be associated with an increased incidence of RC.

Daily Mean Temperature Affects Urolithiasis Presentation in Seoul: a Time-series Analysis

This study aimed to investigate the overall cumulative exposure-response and the lag response relationships between daily temperature and urolithiasis presentation in Seoul. Using a time-series design and distributing lag nonlinear methods, we estimated the relative risk (RR) of urolithiasis presentation associated with mean daily temperature, including the cumulative RR for a 20 days period, and RR for individual daily lag through 20 days. We analyzed data from 14,518 patients of 4 hospitals emergency department who sought medical evaluation or treatment of urolithiasis from 2005-2013 in Seoul. RR was estimated according to sex and age. Associations between mean daily temperature and urolithiasis presentation were not monotonic. Furthermore, there was variation in the exposure-response curve shapes and the strength of association at different temperatures, although in most cases RRs increased for temperatures above the 13°C reference value. The RRs for urolothiasis at 29°C vs. 13°C were 2.54 in all patients (95% confidence interval [CI]: 1.67-3.87), 2.59 in male (95% CI, 1.56-4.32), 2.42 in female (95% CI, 1.15-5.07), 3.83 in male less than 40 years old (95% CI, 1.78-8.26), and 2.47 in male between 40 and 60 years old (95% CI, 1.15-5.34). Consistent trends of increasing RR of urolithiasis presentation were observed within 5 days of high temperatures across all groups. Urolithiasis presentation increased with high temperature with higher daily mean temperatures, with the strongest associations estimated for lags of only a few days, in Seoul, a metropolitan city in Korea.

Multivariate Analyses of Urinary Calculi Composition: A 13-Year Single-Center Study

BACKGROUND

The incidence and prevalence of urinary stone are increasing throughout the world. Compared to the past, recent demographics of patient with urolithiasis compositions are strikingly different. Furthermore, recent clinical studies implied that seasonal cyclicity might influence the distribution of stone composition.

METHODS

We sought to determine the trends in pathogenesis of urolithiasis based on urinary stone analyses. Between 2002 and 2014, a total of 2,383 eligible urinary stone samples from different patients were collected in our center. Infrared spectroscopy was used for urinary calculi analysis. A logistic regression analysis was used to investigate the relationship between urinary calculi composition and calendar month (season), gender, and age in north China during the past 13 years.

RESULTS

Calcium-containing calculi were the most frequent with an overall incidence of 84.1%. Calcium phosphate (CaP) or magnesium ammonium phosphate (MAP) stones were more frequent in females, while monohydrate calcium oxalate (COM), dihydrate calcium oxalate (COD), or uric acid (UA) stones were more common in males. Older individuals were associated with an increased risk of UA stones and a decreased risk of COD, CaP, or cystine stones. Additionally, from 2002 to 2014, the frequency of COD and MAP stone increased, whereas the trend of CaP, UA and cystine stones decreased. However, calendar month (season) was not significantly associated with differences in composition.

CONCLUSION

This study provides the present distribution of urolithiasis compositions in China. From 2002 to 2014, age and gender were significantly associated with stone composition, whereas calendar month was not.

Urinary stones in Eastern Saudi Arabia

INTRODUCTION

Nephrolithiasis is a common problem worldwide especially in areas of the hot climate like Saudi Arabia. The aim of this analysis was to study the characteristics of urinary stones in Eastern Saudi Arabia and to report the following: Composition of urinary stones, age and gender distribution, seasonal variation of stone development, comorbid conditions associated with stone development and the incidence of urinary stones.

METHODS

All urinary stones that were submitted to the Johns Hopkins Aramco Healthcare, previously Saudi Aramco Medical Services Organization for analysis from January 2011 through January 2013 were analyzed.

RESULTS

A total of 384 urinary stones were collected and submitted for analysis from 347 patients. There was a male predominance with a male: female ratio of 3.9:1. The average age was 48.5 ± 12.8 years. Weight abnormality was predominant in both genders, and especially females. Calcium-based stones constituted the great majority (84.6%) followed by uric acid stones (12.8%). The other forms of stones were rare. More stones were recovered during the hot season, May to September. The calculated annual incidence of urolithiasis was 111/100,000 individuals.

CONCLUSION

Calcium based stones are the most common urinary stones observed in Eastern Saudi Arabia. There is a clear association between the diagnosis of urinary stones and the hot season.

Epidemiological Characteristics of Renal Colic and Climate-Related Causes in a Continental Area in Spain

Purpose: The aim of this study was to analyze the incidence of renal colic (RC) in a northwestern area of Spain and its relationship with seasonal and meteorological characteristics. Materials and Methods: We examined 700,257 cases that presented at the emergency room (ER) between 2005 and 2013. We reviewed data such as age, gender, arrival at ER, tests performed and destination after ER. Monthly data regarding temperature, humidity and hours of daylight were taken into account. The Student t-test, the Mann-Whitney test and the Chi-square test were used for the statistical analysis. RC visits were correlated with meteorological characteristics using the Pearson correlation coefficients. Results: A total of 9,330 cases were diagnosed as RC episodes (1.41% of total cases presented). The age range was 14-100 years and mean age was 47 years. Prevalence in men was higher (55.6%) than in women (44.4%). After the seasonal decomposition analysis by month, a significant increase in RC incidence was observed in the months of June, July, August and December (107-114%). There is a statistically significant correlation between mean monthly temperature and RC visit rate (R 0.33, p < 0.001). Conclusion: The incidence of RC in our region is slightly higher than the one described in the literature. A significant increase in RCs is observed in the summer months, as well as a significant correlation between incidence and temperature.

Association with meteo-climatological factors and daily emergency visits for renal colic and urinary calculi in Cuneo, Italy. A retrospective observational study, 2007-2010

The incidence of nephrolithiasis is rising worldwide, especially in women and with increasing age. Incidence and prevalence of kidney stones are affected by genetic, nutritional, and environmental factors. The aim of this study is to investigate the link between various meteorological factors (independent variables) and the daily number of visits to the Emergency Department (ED of the S. Croce and Carle Hospital of Cuneo for renal colic (RC) and urinary stones (UC) as the dependent variable over the years 2007-2010.The Poisson generalized regression models (PGAMs) have been used in different progressive ways. The results of PGAMs (stage 1) adjusted for seasonal and calendar factors confirmed a significant correlation (p < 0.03) with the thermal parameter. Evaluation of the dose-response effect [PGAMs combined with distributed lags nonlinear models (DLNMs)-stage 2], expressed in terms of relative risk (RR) and cumulative relative risk (RRC), indicated a relative significant effect up to 15 lag days of lag (RR > 1), with a first peak after 5 days (lag ranges 0-1, 0-3, and 0-5) and a second weak peak observed along the 5-15 lag range days. The estimated RR for females was significant, mainly in the second and fourth age group considered (19-44 and >65 years): RR for total ED visits 1.27, confidence interval (CI) 1.11-1.46 (lag 0-5 days); RR 1.42, CI 1.01-2.01 (lag 0-10 days); and RR 1.35, CI 1.09-1.68 (lag 0-15 days). The research also indicated a moderate involvement of the thermal factor in the onset of RC caused by UC, exclusively in the female sex. Further studies will be necessary to confirm these results.

The effect of climate variability on urinary stone attacks: increased incidence associated with temperature over 18 °C: a population-based study

The aim of this study was to evaluate the effect of seasonal variation and climate parameters on urinary tract stone attack and investigate whether stone attack is increased sharply at a specific point. Nationwide data of total urinary tract stone attack numbers per month between January 2006 and December 2010 were obtained from the Korean Health Insurance Review and Assessment Service. The effects of climatic factors on monthly urinary stone attack were assessed using auto-regressive integrated moving average (ARIMA) regression method. A total of 1,702,913 stone attack cases were identified. Mean monthly and monthly average daily urinary stone attack cases were 28,382 ± 2,760 and 933 ± 85, respectively. The stone attack showed seasonal trends of sharp incline in June, a peak plateau from July to September, and a sharp decline after September. The correlation analysis showed that ambient temperature (r = 0.557, p < 0.001) and relative humidity (r = 0.513, p < 0.001) were significantly associated with urinary stone attack cases. However, after adjustment for trends and seasonality, ambient temperature was the only climate factor associated with the stone attack cases in ARIMA regression test (p = 0.04). Threshold temperature was estimated as 18.4 °C. Risk of urinary stone attack significantly increases 1.71% (1.02-2.41 %, 95% confidence intervals) with a 1 °C increase of ambient temperature above the threshold point. In conclusion, monthly urinary stone attack cases were changed according to seasonal variation. Among the climates variables, only temperature had consistent association with stone attack and when the temperature is over 18.4 °C, urinary stone attack would be increased sharply.

Temperature, hospital admissions and emergency room visits in Lhasa, Tibet: a time-series analysis

BACKGROUND

Tibet of China, with an average altitude of over 4000 m, has experienced noticeable changes in its climate over the last 50 years. The association between temperature and morbidity (most commonly represented by hospital admissions) has been documented mainly in developed countries. Little is known about patterns in China; nor have the health effects of temperature variations been closely studied in highland areas, worldwide.

OBJECTIVE

We investigated the temperature-morbidity association in Lhasa, the capital city of Tibet, using sex- and age-specific hospitalizations, excluding those due to external causes.

METHODS

A distributed lag non-linear model (DLNM) was applied to assess the nonlinear and delayed effects of temperature on morbidity (including total emergency room visits, total and cause-specific hospital admissions, sex- and age-specific non-external admissions).

RESULTS

High temperatures are associated with increases in morbidity, to a greater extent than low temperatures. Lag effects of high and low temperatures were cause-specific. The relative risks (RR) of high temperature for total emergency room visits and non-external hospitalizations were 1.162 (95% CI: 1.002-1.349) and 1.161 (95% CI: 1.007-1.339) respectively, for lag 0-14 days. The strongest cumulative effect of heat for lag 0-27 days was on admissions for infectious diseases (RR: 2.067, 95% CI: 1.026-4.027). Acute heat effects at lag 0 were related with increases of renal (RR: 1.478, 95% CI: 1.005-2.174) and respiratory diseases (RR: 1.119, 95% CI: 1.010-1.240), whereas immediate cold effects increased admission for digestive diseases (RR: 1.132, 95% CI: 1.002-1.282). Those ≥65 years of age and males were more vulnerable to high temperatures.

CONCLUSION

We provide a first look at the temperature-morbidity relationship in Tibet. Exposure to both hot and cold temperatures resulted in increased admissions to hospital, but the immediate causes varied. We suggest that initiatives should be taken to reduce the adverse effects of temperature extremes in Tibet.

Nationwide survey to evaluate medical utilization by patients with inguinal hernia and the risk of developing varicocele in Taiwan

BACKGROUND

The purpose of this study was to analyze age, geographical and seasonal variations in medical service utilization by patients with inguinal hernia in Taiwan, and the influence of herniorrhaphy on development of ipsilateral varicocele in male patients.

METHODS

Between 2001 and 2008, comprehensive data on the characteristics of medical service utilization by patients with inguinal hernia was evaluated via a retrospective nationwide population-based study. Data were obtained from the National Health Insurance Research Database in Taiwan. Parameters for comparison included newly diagnosed inguinal hernia cases, number of herniorrhaphies, and incidence rates every year, number of outpatient visits for inguinal hernia, and herniorrhaphy by age, season, and area of Taiwan.

RESULTS

There was an average of 1,466 newly diagnosed inguinal hernia cases and 871.9 herniorrhaphies performed per year per million population during the study period. The male ratio for both newly diagnosed inguinal hernia cases and number of herniorrhaphies increased significantly by age. The number of newly diagnosed inguinal hernia cases and outpatient visits for inguinal hernia was highest during summer, followed by spring, autumn, and winter, and in the north of Taiwan, followed by the center, south, and east. Additionally, the incidence of developing ipsilateral varicocele after herniorrhaphy was low in male patients.

CONCLUSION

The number of newly diagnosed inguinal hernia cases and outpatient visits for inguinal hernia is highest during summer and lowest in eastern Taiwan. In addition, the incidence of developing ipsilateral varicocele after herniorrhaphy is higher in patients aged 10-19 years.

Impact of fluid intake in the prevention of urinary system diseases: a brief review

We are often told that we should be drinking more water, but the rationale for this remains unclear and no recommendations currently exist for a healthy fluid intake supported by rigorous scientific evidence. Crucially, the same lack of evidence precludes the claim that a high fluid intake has no clinical benefit. The aim of this study is to describe the mechanisms by which chronic low fluid intake may play a crucial role in the pathologies of four key diseases of the urinary system: urolithiasis, urinary tract infection, chronic kidney disease and bladder cancer. Although primary and secondary intervention studies evaluating the impact of fluid intake are lacking, published data from observational studies appears to suggest that chronic low fluid intake may be an important factor in the pathogenesis of these diseases.

Association of summer temperatures with hospital admissions for renal diseases in New York State: a case-crossover study

This study assessed the association between high temperatures and increased odds of hospitalization for renal diseases that, to date, has been examined in only a small number of studies. A case-crossover design was used to study 147,885 hospital admissions with renal diagnoses during July and August, 1991-2004, in New York State. Regional temperature, humidity, and barometric pressure data from automated monitors were used as exposure indicators. By use of time-stratified referent selection and conditional logistic regression analysis, an overall 9% increase in odds of hospitalization for acute renal failure per 5°F (2.78°C) was found for mean temperature at a 1-day lag (odds ratio = 1.09, 95% confidence interval: 1.07, 1.12). The results suggest increased susceptibility to hospitalization for acute renal failure for blacks, Hispanics, people aged 25-44 years, and those in the lowest income quartile. The odds varied geographically with the largest associations found in the more urban regions. Increased odds of hospitalization were also found for urinary tract infections, renal calculi, lower urinary calculi, and other lower urinary tract disorders. The findings can help to identify vulnerable subpopulations and to inform decisions and policies regarding adaptation strategies and heat-warning systems.

Mean temperature and humidity variations, along with patient age, predict the number of visits for renal colic in a large urban Emergency Department: results of a 9-year survey

Background: A marked geographic variability has been reported in stone disease, partially attributed to the Mean Annual Temperature (MAT), as well as to the seasonal fluctuations of climatic conditions. Accordingly, peaks in Emergency Department (ED) visits for renal colic are commonplace during the summer.

Materials and methods: The aim of this study was to assess the influence of day-by-day climate changes on the number of visits as a result of renal colic in the ED (City of Parma, northern Italy, temperate continental climate). A total of 10,802 colic episodes were retrieved from the database during a period of 3286 days (January 2002 to December 2010).

Results: The analysis of the data confirms a peak of renal colic cases during the summer, especially in July (maximum number of 4.1 cases of renal colic per day), and a winter nadir (minimum number of 2.7 cases of renal colic per day, in February). The linear regression analysis shows a high and significant correlation between the mean number of cases of renal colic per day and both the mean daily temperature (positive association, R = 0.93; p < 0.0001) and the mean daily humidity (negative association, R = −0.82; p < 0.0001). The influence of temperature and humidity on the incidence of renal colic cases varied widely among age groups, the highest incidence seen in patients aged between 30 and 40 years, and the lowest seen for those aged <20 and >70 years of age.

Conclusion: The combined data suggest that the hot and dry climate would favor an acceleration of the process of stone formation, which seems more pronounced in the older population.

[Climate and epidemiological characteristics of renal colic attendances in an urban setting in Spain]

OBJECTIVES

To address the real incidence of RC episodes in our setting and its relationship with several epidemiological, seasonal and climatic factors.

MATERIAL AND METHODS

We analyzed 156,687 attendances in the emergency unit of Hospital Infanta Cristina (Parla, Madrid, Spain), from the opening of the unit in 07/04/2008 to the date of analysis (28/03/2010). Date of birth, sex, history of previous urinary lithiasis episodes, main cause and date of attendance were collected. Daily climate parameters (maximum daily temperature and percent relative humidity) were recorded.

RESULTS

A total number of 1,866 RC episodes (1.19% of all attendances) were recorded during the study period. Age ranged from 15 to 94 years, median 39. RC episodes were more prevalent in male population (58.4% vs 41.6% in females respectively, p<0.001). No differences were observed with regard to previous history of RC. A modest but significant rise in RC incidence was observed during summer and autumn. No significant correlation was observed between monthly or seasonal number of RC attendances and the climatic parameters studied.

CONCLUSIONS

RC incidence in our setting is similar to the previously reported in the literature. A modest but significant higher incidence of renal colic episodes were observed during summer and autumn seasons, although no significant relationship was attributed to temperature and humidity values. Absence of dramatic seasonal changes in incidence can be explained by the "non-extreme" weather conditions in the studied setting.

Use of Google Insights for Search to track seasonal and geographic kidney stone incidence in the United States

OBJECTIVE

To determine whether Internet search volume for kidney stones has seasonal and geographic distributions similar to known kidney stone incidence.

MATERIAL AND METHODS

Google Insights for Search analyzes a portion of Google web searches from all Google domains to compute how many searches are performed for a given term relative to the total number of searches done over a specific time interval and geographic region. Selected terms related to kidney stones were examined to determine which most closely tracked kidney stone incidence. Google Insights for Search data were correlated with hospital admissions for the emergent treatment of nephrolithiasis found through the Nationwide Inpatient Sample. Ambient temperature in Seattle and New York were compared with search volume for these regions to display qualitative relationships.

RESULTS

The term "kidney stones" had the highest seasonal correlation of terms examined (r = .81, P = .0014). Google Insights for Search output and national Inpatient Sample admissions also correlated when regions were compared (r = .90, P = .005). Qualitative relationships between ambient temperatures and kidney stone search volume do exist.

CONCLUSIONS

Internet search volume activity for kidney stones correlates with temporal and regional kidney stone insurance claims data. In the future, with improved modeling of search detection algorithms and increased Internet usage, search volume has the potential to serve as a surrogate for kidney stone incidence.

Regional short-term climate variations influence on the number of visits for renal colic in a large urban Emergency Department: results of a 7-year survey

The pathogenesis of renal stones is an intricate process and varies widely depending on the composition of stones. There is also a marked geographic variability, strongly attributable to the mean annual temperature (MAT) and, to a lesser extent, on the seasons. Previous investigations report peaks in Emergency Department (ED) visits for renal colic during the summer. The aim of the present investigation is to assess the influence of day-by-day climate changes on the number of visits due to renal colic in our ED (city of Parma, located in the Po river valley, with a temperate continental climate). A total of 8,168 colic episodes were retrieved from our database during a period of 2,557 days (from 1 January 2002 to 31 December 2008). Over the same period 557,990 patients were admitted to our ED, renal colic visits representing 1.46% of the total. The linear regression analysis fitting the mean number of colic visits per day and the mean daily temperature displays a very high and significant correlation (R = 0.88, p < 0.0001). A multiple linear regression analysis between the mean temperature of each of the 30 days preceding the colic episode also shows strong correlations, being the strongest on the 5th-7th days (R = 0.80, p < 0.0001 on the 6th day before the colic episode), and a weaker but highly significant correlation on days 14 (R = 0.77, p < 0.0001) and 20 (R = 0.70, p < 0.0001) before the colic episode. Taken together, these findings suggest a kind of "acceleration" process of stone formation caused by the hot climate and, perhaps, by dietary variations during the summer. This process might trigger a sudden growth of the stone and, finally, the resulting clinical episode.

Ambient temperature as a contributor to kidney stone formation: implications of global warming

Nephrolithiasis is a common disease across the world that is becoming more prevalent. Although the underlying cause for most stones is not known, a body of literature suggests a role of heat and climate as significant risk factors for lithogenesis. Recently, estimates from computer models predicted up to a 10% increase in the prevalence rate in the next half century secondary to the effects of global warming, with a coinciding 25% increase in health-care expenditures. Our aim here is to critically review the medical literature relating stones to ambient temperature. We have categorized the body of evidence by methodology, consisting of comparisons between geographic regions, comparisons over time, and comparisons between people in specialized environments. Although most studies are confounded by other factors like sunlight exposure and regional variation in diet that share some contribution, it appears that heat does play a role in pathogenesis in certain populations. Notably, the role of heat is much greater in men than in women. We also hypothesize that the role of a significant human migration (from rural areas to warmer, urban locales beginning in the last century and projected to continue) may have a greater impact than global warming on the observed worldwide increasing prevalence rate of nephrolithiasis. At this time the limited data available cannot substantiate this proposed mechanism but further studies to investigate this effect are warranted.

The demographic profile of urolithiasis in Iran: a nationwide epidemiologic study

OBJECTIVE

The marked variations in urinary stone disease prevalence by age, gender, race, and geographic location may provide clues to their etiology and prevention. We investigated the demographic profile of urolithiasis across Iran to draw out implications for national healthcare policies.

MATERIALS AND METHODS

In a nationwide multi-center epidemiologic study from September 2006 to August 2007, a multi-stage stratified sampling was taken in 12 ecologic zones across Iran during four seasons. 6,089 imaging-proven cases were identified out of 117,956 referrals to the radiologic centers. The demographic characteristics of positive cases were determined by a detailed questionnaire. Target population characteristics were derived from the most recent formal national census (2006).

RESULTS

Male-to-female ratio was 1.38 (male: 58%, female: 42%). Uneducated people ratio was significantly greater among stone formers. (Mean difference = 10.4%, 95% CI = 9-12%).Mean age at presentation was 41.5 years +/- 16.3 and the peak incidence range was between 55 and 65 years. The most frequent co-existence diseases were hypertension (15.8%) and diabetes (11.4%). It ranged from 2.8 to 21.3 for diabetes and 6.1 to 30.4 for hypertension compared to 1 to 4.2% and 4 to 7.7, respectively, in the general population. Surprisingly, the number of current smokers among stone formers was significantly less than the general population. BMI failed to show a significant correlation.

CONCLUSIONS

The putative risk factors for urinary stone disease were male gender, hypertension, diabetes mellitus, and lack of education. Preventive strategies based on indigenous demographic data may have a role in public healthcare policies.

Seasonal variation in the incidence of spontaneous pneumothorax and its association with climate: a nationwide population-based study

This study investigated seasonal variation in the incidence of spontaneous pneumothorax (SP) among young adults aged 15-44 years, in order to identify possible associations with meteorological parameters in a subtropical Asian climate. Neither particular months nor seasons of the year were significantly associated with the incidence of SP.

BACKGROUND AND OBJECTIVE

While links between meteorological conditions and the incidence of spontaneous pneumothorax (SP) have been postulated, the findings are controversial. In this first large-scale, nationwide, population-based study, seasonal variation in the incidence of SP among young adults aged 15-44 years was investigated, in order to identify possible associations with meteorological parameters (rainfall, ambient temperature, relative humidity, atmospheric pressure, hours of sunshine) in a subtropical Asian climate.

METHODS

Data (2001-2005) from the National Health Insurance Research Database were used to identify a total of 8575 patients who had been hospitalized with a principal diagnosis of SP. The autoregressive integrated moving average method was used to evaluate the effects of seasonality and monthly climatic factors on the incidence of SP.

RESULTS

The incidence of SP was not significantly associated with either particular months of the year or seasons. After adjusting for seasonality, month and time trends, relative humidity was positively associated with the monthly incidence of SP among men, while ambient temperature and rainfall were significantly associated with SP events among women. However, changes in monthly atmospheric pressure did not appear to influence the monthly risk of SP.

CONCLUSIONS

These results do not support the premise that seasonal factors are involved in precipitating SP, although certain climatic parameters showed weak associations with the incidence of SP. Future studies should investigate other combinations of weather phenomena and potential triggering factors, in order to shed light on the occurrence of SP in various regions and climatic conditions, and among both men and women.