Kidney stone disease is characterized by a relatively high rate of recurrence. In our study, we analyzed the association between RSS and the risk of stone recurrence. Additionally, we examined the association between changes in RSS and of urinary composition after 1 week of medical treatment and the risk of recurrence.
We performed a post-hoc analysis of data from a previously published randomized controlled trial comparing the effect of two diets in 120 men with recurrent calcium oxalate stones and hypercalciuria. Baseline and follow-up 24h urine parameters were used to calculate RSS for calcium oxalate, calcium phosphate and uric acid using different computer programs EQUIL-2, JESS and Lithorisk. Cox models were used to compute estimates of association between each baseline RSS and 1-week changes and risk of recurrence during follow-up.
During a 5-year follow-up, 35 patients (34%) experienced recurrence. Reduction in RSS for calcium oxalate at 1 week was significantly associated with lower risk of recurrence when using the EQUIL-2 calculation (for every 10% reduction from baseline HR 0.92, 95% CI 0.86, 1.00, p=0.044), whereas there was no association for RSS calculated with other methods nor for RSS of other salts. Changes in 24h urine excretions of citrate, potassium and magnesium were significantly associated with risk of recurrence.
In recurrent stone formers with hypercalciuria, baseline values and changes in RSS for calcium oxalate may be associated with risk of recurrence. Changes in urinary citrate, potassium and magnesium following dietary intervention may also be predictive.
The Journal of urology. 2018 Jun 22 [Epub ahead of print]
Pietro Manuel Ferraro, Andrea Ticinesi, Tiziana Meschi, Allen Rodgers, Federica Di Maio, Pierluigi Fulignati, Loris Borghi, Giovanni Gambaro
Divisione di Nefrologia, Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Via G. Moscati 31, 00168 Rome (Italy). Electronic address: ., Department of Medicine and Surgery, University of Parma; Medical-Geriatric-Rehabilitation Department, Azienda Ospedaliero-Universitaria di Parma, Via Antonio Gramsci 14, 43126 Parma (Italy)., Department of Chemistry, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)., Divisione di Nefrologia, Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Via G. Moscati 31, 00168 Rome (Italy).