Clinical Question: What are the most cost-effective treatment strategies for the medical management of patients with kidney stones?

Setting: Population-based

Study Design: Cost-effectiveness analysis

Synopsis: Investigators from Texas constructed a decision tree to estimate the cost of treatment and follow-up in patients with calcium oxalate renal stones. Using MEDLINE, they identified studies addressing the natural history, evaluation, and medical and surgical treatment of nephrolithiasis. Costs of various outcomes were estimated using local hospital and pharmacy charges from two national chains for specified diagnostic tests, medications, and surgical procedures.

Six treatment strategies were evaluated: (1) conservative therapy—dietary modification without drug treatment or metabolic evaluation; (2) empiric medical therapy—dietary modification and drug treatment (potassium citrate) for all patients; (3) modified simple metabolic evaluation—a single 24-hour urine collection for analysis of common urinary stone risk factors, with potassium citrate and hydrochlorothiazide prescribed for patients with hypercalciuria, and potassium citrate alone for patients with normocalciuria; (4) simple metabolic evaluation—the same evaluation as no. 3, except that patients with normocalciuria and no other identifiable abnormality received no drug therapy; (5) modified comprehensive metabolic evaluation—at least two 24-hour urine collections for stone risk analysis and a fasting oral calcium load test with similar treatment as in no. 3; and (6) comprehensive metabolic evaluation—the same work-up as in no. 5, but with treatment only for patients with an identified disorder. A sensitivity analysis evaluated medication cost thresholds at varying levels of risk that would achieve cost equivalence with conservative (i.e., diet only) therapy for each treatment strategy.

In patients with first-time kidney stones, conservative therapy was the most cost-effective strategy. In patients with recurrent kidney stones, empiric therapy and the modified simple metabolic evaluation were equally the most cost-effective strategies.

Bottom Line: In patients with first-time kidney stones, conservative therapy (i.e., dietary modification only) is the most cost-effective strategy. In patients with recurrent kidney stones, empiric therapy (i.e., dietary modification and potassium citrate) and a modified simple metabolic evaluation (i.e., a single 24-hour urine collection for renal stone risk factors, with potassium citrate and hydrochlorothiazide for patients with hypercalciuria and potassium citrate alone for patients with normocalciuria) are equally cost-effective. (Level of Evidence: 2b)