Urinary Supersaturation in a Randomized Trial Among Individuals with Recurrent Nephrolithiasis Comparing Empiric...

To compare a strategy using testing to guide treatment, also known as selective therapy, with a strategy of initiating interventions without testing, termed empiric therapy, on urinary supersaturation of calcium oxalate and calcium phosphate.

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 comprised 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.

The analytic sample included 56 participants (mean [SD] age, 44.5 [13.2] years; 30 women [54%]), with 29 randomized to the empiric and 27 to the selective groups. At week 8, there were no significant differences comparing the empiric and selective arms with respect to mean [SD] urinary supersaturation of calcium oxalate (4.7 [2.9] vs 5.0 [2.9], respectively, P = .81) or calcium phosphate (1.3 [0.9] vs 1.4 [1.1], respectively, P = .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.

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 vs selective strategy for kidney stone prevention.