Potential for Urolithiasis-related Research Using the Novel Medicare-Litholink Database

Abstract

Introduction: To overcome the data availability hurdle of observational studies on urolithiasis, we linked claims data with 24-hour urine results from a large cohort of adults with urolithiasis. This database contains the sample size, clinical granularity, and long-term follow-up needed to study urolithiasis on a broad level.

Methods: We identified adults enrolled in Medicare with urolithiasis who had a 24-hour urine collection processed by Litholink (2011 to 2016). We created a linkage of their collections results and paid Medicare claims. We characterized them across a variety of sociodemographic and clinical factors. We measured frequencies of prescription fills for medications used to prevent stone recurrence, as well as frequencies of symptomatic stone events, among these patients.

Results: In total, there were 11,460 patients who performed 18,922 urine collections in the Medicare-Litholink cohort. The majority were male (57%), White (93.2%), and lived in a metropolitan county (51.5%). Results from their initial urine collections revealed abnormal pH to be the most common abnormality (77.2%), followed by low volume (63.8%), hypocitraturia (45.6%), hyperoxaluria (31.1%), hypercalciuria (28.4%), and hyperuricosuria (11.8%). Seventeen percent had prescription fills for alkali monotherapy, and 7.6% had prescription fills for thiazide diuretic monotherapy. Symptomatic stone events occurred in 23.1% at 2 years of follow-up.

Conclusions: We successfully linked Medicare claims with results from 24-hour urine collections performed by adults that were processed by Litholink. The resulting database is a unique resource for future studies on the clinical effectiveness of stone prevention strategies and urolithiasis more broadly.

Keywords: database; health services research; kidney calculi; outcome assessment, health care; urolithiasis.

Figure 1:

Frequency of Urine Abnormalities on Initial Collection. Possible abnormalities included low urine volume, hypercalciuria, hyperoxaluria, hypocitraturia, hyperuricosuria, and low or high urine pH.

Figure 2.

Frequency of Symptomatic Stone Events by Urine Abnormality. Abbreviation: ED, emergency department