Health Care Spending Associated With Preventative Pharmacologic Therapy for Urolithiasis.

Introduction: Urolithiasis is among the most expensive urologic conditions from a payer standpoint. Preventative pharmacologic therapy (PPT) can reduce symptomatic recurrences; however, the potential savings from fewer recurrences may be offset by medication costs. This study aimed to evaluate the cost of PPT from the payer perspective.

Methods: The Medicare-Litholink database was queried for beneficiaries with urolithiasis who had at least 1 urinary chemistry abnormality. Payments made on their behalf, along with out-of-pocket costs, were measured. Payments were compared among 3 groups using 2-part generalized linear models: patients prescribed guideline-concordant PPT who adhered to therapy, those prescribed PPT but did not adhere, and untreated patients.

Results: Among 16,329 patients who met inclusion criteria, 30.8% were prescribed PPT. Alkali therapy represented 42.7% of all spending among adherent patients, whereas thiazides and uric acid-reducing therapies combined contributed only 3.3%. Out-of-pocket spending on alkali represented 88% of total prescription costs for adherent patients. For patients with hypocitraturia or low pH, adherence to therapy resulted in the lowest mean cost for symptomatic stone events but the highest overall costs due to medication expenses. Conversely, in hypercalciuria and hyperuricosuria, nonadherent patients were the most expensive overall even after multivariable adjustment.

Conclusions: Among patients with hypocitraturia and low pH, adherence was the most expensive, driven by medication costs. Conversely, among patients with hypercalciuria and hyperuricosuria, nonadherence was costliest. Although PPT can lead to reduced costs due to averted stone events, medication adherence is critical to ensuring these savings are fully realized.