EAU 2017: State-of-the-art Lecture – The Swiss Kidney Stone Cohort: Unraveling The Cause Of Renal Stones.

London, England (UroToday.com) Dr. Beat Roth started his plenary lecture with referring to the epidemiological studies that have shown the incidence and prevalence of urinary stone disease to be on the rise and the cost approximately associated with the diagnosis, management and preventive treatment modalities will be approximately 5 billion USD/year1. He continued that in addition to the dramatic cost, stone disease is linked to hypertension, diabetes, and cardiovascular disease comorbidities and 50% of stone patients who undergo a certain type of treatment will experience a recurrence within the next 5 years of initial presentation. Dr. Roth mentioned that this is due to stone clinics with metabolic workup and preventive measures for stone disease are being vastly underused and reported to be only around 7.4%2. Indeed, although current state of the literature in stone disease has some significant knowledge accumulated on urinary stone formation, diagnosis and treatment, there remains a significant gap to be filled and questions to be answered, such as the correlation with bone disease and cardiovascular disease, the mechanism in idiopathic stone formers, and finally what the best treatment is for hyperuricosuric stone formers.

Dr. Roth continued that in an effort to address these questions, a Swiss Stone Initiative was started in 2014 to prospectively collect data from stone formers from 5 medical centers (Zurich, Basel, Bern, Geneva, and Lausanne). He said that more centers are expected to join this initiative in the near future and contribute to the prospective database that will potentially elaborate on many important scientific questions. He briefly mentioned the inclusion criteria for the registry was recurrent stone formation or first time stone formers with risk factors such as gout, diabetes, and solitary kidney. All patients who meet the criteria and included will undergo a standardized initial laboratory and clinical evaluation. Data is collected at baseline, 3 months and yearly thereafter. Collected data includes anthropomorphic data, cristalluria, samples for biobanking and much more. A goal was set to collect data on 1000 patients and after finalizing recruitment, follow-up will continue for another three years and it is estimated that the study will be completed in 2020. Total budget for the entire study is estimated to be around 3 Million Euros. To date a total of 426 patients have been included.

Dr. Roth reported on the initial analysis of their preliminary data and showed that indeed Calcium Oxalate stones are most prevalent in Swiss population. Average volume of 24h urinalysis is 1732.6 +-811.3 ml, with 61% of patients under the 2l/24h cutoff, a significantly higher percentage than the 5.6% from the London cohort, published in 2015 by Ferraro and colleauges3. Only 1.5% of patients had hyperoxaliuria (>400micromol/24h), 27% had hypocitraturia (1.67mmol/24h), 30% had hypercalciuria, 35% had hypernatriuria (>200mmol/24h).

Dr. Roth revealed that in the near future, there are plans to elaborate more projects will be drawn from this initiative, 3 of which are already running include:
- Does shockwave lithotripsy impair urinary pH?
- Food intake assessed by food diary and comparison with 24h urinalysis results. This project has shown that self-reported food intake is of poor quality and that an intake diary is best assessed with the help of a dieticians.
- The no stone project (www.nostone.ch) double blinded, placebo controlled trial on low versus high dose of hydrochlorothiazide in the prevention of recurrent calcium containing nephrolithiasis. Although there is lots of data on this subject, the overall quality of evidence is low. So far 416 patients included in a 4-arm study: placebo, 12.5mg, 25 mg and 50 mg.
More projects for the future:
• Assess different ways of food intake assessment
• Assess influence of dietary changes
• Assess and correlate bone markers in patients with stone disease
• Identify genetic determinants.

Dr. Roth concluded that despite significant financial challenges in the foreseeable future of the database, this prospective cohort, with its standardized protocol and expected large number of patients included will provide us with a vast amount of data, allowing us to better research kidney stone formation. Research projects are welcome and can be proposed to: http://sksc.nccr-kidney.ch/index.php?nav=106&scx=0&scy=0.salary

Presenter: Beat Roth, MD; Department of Urology, University of Bern, Bern, Switzerland

Written By: Zhamshid Okhunov, MD, University of California, Irvine

at the #EAU17 - March 24-28, 2017- London, England