To determine if medical therapy affects long-term clinical outcomes in uric acid stone formers (UASF).

We identified 53 UASF who had complete stone clearance following stone procedure by computed tomography (CT) and had ≥1 post-operative 24-hour urine collection and a clinical follow-up ≥6 months with a surveillance CT scan. Patients were divided into “adherent to medical therapy” (compliance with potassium citrate ± allopurinol verified by computerized pharmacy data) or non-adherent groups. Primary outcomes were CT stone recurrence rate and need for surgical stone intervention.

We found 28/53 (53%) adherent and 25/53 (47%) non-adherent individuals (14 declined medication, 11 intolerant). With median follow-up of 24 months, no significant differences were noted between groups in regards to stone recurrence (32%; p=0.99) or in 24-hour urine pH compared to baseline or follow-up (range 5.46 – 5.62; p=0.06). Adherent patients, however, had smaller CT stone recurrence sizes (6.3±3.8 vs 11.8±6.2 mm, p=0.02), were 28% less likely to require stone surgery compared to those without therapy (p<0.01), and trended towards longer time intervals without recurrence (23.1±18.8 vs 10.5±7.5 months, p=0.10) compared to non-adherents. Study confounders included a variety of medication dosages and adherences, limited non-adherent follow-up, and small study number.

UASF adherent to medical therapy had smaller recurrence sizes and fewer surgical interventions versus non-adherent, highlighting the protective role of potassium citrate in UA stone disease. The comparable urine pH and stone recurrence rates between groups, however, underscore areas for improvement in future UA stone prevention strategies.

Urology. 2019 May 31 [Epub ahead of print]

Benjamin K Canales, Nitin Sharma, Stanislav V Yuzhakov, Shahab Bozorgmehri, Brandon J Otto, Vincent G Bird

Department of Urology, University of Florida, Gainesville, Florida USA. Electronic address: ., Department of Urology, University of Florida, Gainesville, Florida USA.