Empiric Versus Selective Prevention Strategies for Kidney Stone Disease

Diet and pharmacologic interventions for preventing future kidney stone episodes are effective, however clinical guideline panels disagree on whether clinicians should perform selective therapy: performing 24-hour urine testing to guide choosing interventions to correct abnormal urinary parameters. The alternative strategy is empiric therapy: applying interventions without 24-hour urine testing. While 24-hour urine testing is considered the standard of care by nephrology and urology specialties for higher risk patients, the American College of Physicians does not recommend 24-hour urine testing.

This is a randomized clinical trial of selective versus empiric therapy for patients with presumed idiopathic calcium stone disease, representing >80% of the kidney stone population. The primary outcome is change in urinary supersaturation, which associates with symptomatic stone recurrence. We will recruit patients with presumed idiopathic calcium stone disease with at least 2 stone events within the previous 5 years. Participants will be randomly assigned to empiric diet plus thiazide with potassium citrate daily, or to selective diet plus pharmacologic therapy based on the 24-hour urine abnormalities identified at baseline and adjusted during follow-up. The primary outcomes will be the calculated calcium oxalate and calcium phosphate supersaturations. In addition, we will determine adverse effects from, and adherence to, selective and empiric strategies.

Inclusion criteria

• Two or more symptomatic kidney stone events in the last 5 years
• Adult

Exclusion criteria

• Medullary sponge kidney or renal tubular acidosis
• Untreated urinary obstruction
• Primary hyperparathyroidism
• Primary hyperoxaluria
• Pregnancy
• Inflammatory bowel disease or bowel resection
• Sarcoidosis
• Cystinuria
• Prior stone composition with uric acid, struvite, cystine, carbonate apatite
• Use of specific medications (thiazides, topiramate, xanthine oxidase inhibitors, citrate, bicarbonate)
• Chronic kidney disease stage 3 or higher (eGFR<60)
• Gouty arthritis or 3 gout episodes in 1 year
• Known allergy to study medications
• Hypokalemia or hyponatremia at screening.
• Age < 18 years