Urinary Supersaturation in a Randomized Trial among Individuals with Recurrent Nephrolithiasis comparing Empiric versus Selective Preventive Therapy: The URINE Trial

PURPOSE: To compare a strategy utilizing testing to guide treatment, also known as selective therapy, to a strategy of initiating interventions without testing, termed empiric therapy, on urinary supersaturation of calcium oxalate and calcium phosphate. MATERIALS AND METHODS: In this single-center trial, adult individuals with recurrent idiopathic calcium stone disease were randomized to either an empiric or selective strategy. Participants received 24-hour urine testing at baseline, 4 weeks, and 8 weeks. Treatment in the empiric arm was comprised of dietary and fluid counseling and pharmacologic treatment with indapamide and potassium citrate irrespective of 24-hour urine results. For the selective arm, diet and pharmacologic treatments, which included indapamide, potassium citrate, and/or allopurinol, were tailored based on urine testing at baseline and 4 weeks. The primary outcome was urinary supersaturation of calcium oxalate and calcium phosphate at 8 weeks. RESULTS: = 0.58). Similarly, there were no significant differences at 8 weeks in urine volume and pH, or in excretion of calcium, oxalate, citrate, uric acid, and sodium. CONCLUSIONS: In this short-term trial among individuals at high-risk for stone recurrence, there was no statistically significant difference in the urinary stone risk comparing an empiric versus selective strategy for kidney stone prevention.