Regional and seasonal variation in the incidence of urolithiasis in Iran: a place for obsession in case finding and statistical approach

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.

Service quality and urolithiasis patient adherence

PURPOSE

Adherence to preventive recommendations improves clinical outcomes and is compulsory for long-term prevention in urolithiasis patients. Service quality can affect patients' adherence to treatment and care. The purpose of this paper is to compare perceived service quality, using the SERVQUAL model, between urolithiasis patients who were nonadherent to their follow-up visits and those who were adherent, in a stone prevention clinic, Tehran, Iran.

DESIGN/METHODOLOGY/APPROACH

This was a cross-sectional study on patients with urolithiasis referred to the Shahid-Labbafinejad Hospital stone prevention clinic between 2010 and 2014. All patients withdrawing from follow-up visits were selected as the nonadherent group. Patients with follow-up visits were randomly selected and appointed as the adherent group. Data included demographic, service quality (assessed using the SERVQUAL) and a questionnaire about the reason for withdrawal from follow-up visits. Man-Whitney U test, χ² and binary logistic regression were used for data analyses.

FINDINGS

In total, 531 nonadherent and 51 adherent patients entered the study. SERVQUAL results revealed that patients' expectations were significantly higher than their perceptions in all five service quality dimensions in both groups. The adherent group had better-quality scores. Responsibility, assurance and empathy scores significantly increased patient adherence odds.

RESEARCH LIMITATIONS/IMPLICATIONS

Uni-center design; missing data, such as socioeconomic status and disease severity, which may influence treatment adherence; and missing data regarding adherence to medication and dietary advice were limitations.

PRACTICAL IMPLICATIONS

Service quality needs to be improved in all dimensions.

ORIGINALITY/VALUE

Since responsiveness, assurance and empathy dimensions determined patients' adherence, giving special attention to these dimensions could improve patient adherence.

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.

Epidemiology of urolithiasis in Asia

In Asia, about 1%-19.1% of the population suffer from urolithiasis. However, due to variations in socio-economic status and geographic locations, the prevalence and incidence have changed in different countries or regions over the years. The research for risk factors of urinary tract stones is of predominant importance. In this review, we find the prevalence of urolithiasis is 5%-19.1% in West Asia, Southeast Asia, South Asia, as well as some developed countries (South Korea and Japan), whereas, it is only 1%-8% in most part of East Asia and North Asia. The recurrence rate ranges from 21% to 53% after 3-5 years. Calcium oxalate (75%-90%) is the most frequent component of calculi, followed by uric acid (5%-20%), calcium phosphate (6%-13%), struvite (2%-15%), apatite (1%) and cystine (0.5%-1%). The incidence of urolithiasis reaches its peak in population aged over 30 years. Males are more likely to suffer from urinary calculi. Because of different dietary habits or genetic background, differences of prevalence among races or nationalities also exist. Genetic mutation of specific locus may contribute to the formation of different kinds of calculi. Dietary habits (westernized dietary habits and less fluid intake), as well as climatic factors (hot temperature and many hours of exposure to sunshine) play a crucial role in the development of stones. Other diseases, especially metabolic syndrome, may also contribute to urinary tract stones.

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.

Modeling the distribution of urolithiasis prevalence under projected climate change in Iran

Although studies support a positive correlation between temperature and stone risk, the precise relationship between these factors has not been elucidated. We modeled the current distribution of urolithiasis prevalence in Iran using 26 bioclimatic, climatic and topographic variables based on two multivariate linear regression models in geographical information system. The impact of climate change on the stone prevalence was predicted under the projections of GFDL-ESM2G, CCSM4 and HadGEM2-ES climate models by mid-century (2050). Extraterrestrial radiation and isothermality in the first regression model and annual mean temperature, precipitation seasonality and isothermality in the second model were the significant (P<0.01) predictors of urolithiasis prevalence. Both regression models provided good estimates of the stone prevalence (R2>0.9) and determined a mean urolithiasis prevalence of 6% (range of 1.5-10.8%) in Iran. The climate change under the projections of GFDL-ESM2G, CCSM4 and HadGEM2-ES models can, respectively, lead to an average increase of 5.7, 4.3 and 9% in the urolithiasis prevalence based on the second regression model by 2050. The highest increase of the prevalence will occur in the west, northwest and southwest provinces of the country. Predicting the impact of climate change on climate-related diseases can be useful for effective preventive measures.

Association between calcium-sensing receptor gene polymorphisms and recurrent calcium kidney stone disease: a comprehensive gene analysis

OBJECTIVE

Comprehensive sequencing of the coding exons of the calcium-sensing receptor gene (CASR) was performed in a group of Iranian recurrent calcium kidney stone-formers and the results were compared with a control group.

MATERIAL AND METHODS

Serum and urine parameters were evaluated in 99 males aged between 30 and 55 years old with idiopathic recurrent calcium urolithiasis and in 107 men as a control group. Products of polymerase chain reaction were sequenced using forward primer until a mutation was found in that exon. Then, other cases were analysed by single-strand conformation polymorphism.

RESULTS

Four polymorphisms were detected in CASR exons, all in the coding region of exon 7. These polymorphisms and their minor allele frequency were P748P (100%), A986S (1%), R990G (3%) and E1011Q (98%). There was a significantly higher count of 986S (p = 0.006), 990G (p = 0.006) and E1011 (p = 0.02) alleles in patients. The odds ratio (95% confidence interval) was 2.55 (1.31-4.96) in those at risk of stone disease for the 986S allele and 8.06 (1.80-35.9) for the 990G allele. Men with the RR genotype at R990G showed a significantly higher serum ionized calcium than the RG or GG group (p = 0.03). A significantly lower serum total calcium was found in subjects with the QQ than the EQ genotype with respect to the 1011 locus (p = 0.005). Furthermore, the 1011Q allele was marginally associated with hypercalciuria (p = 0.05).

CONCLUSION

The 986S, 990G and 1011Q alleles were associated with a recurrent calcium kidney stone-forming state. 986S and 1011Q alleles, but not 986S, were associated with hypercalcaemia.

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.