Presentation Authors: Shen Song*, I-Chun Thomas, Calyani Ganesan, Ericka Sohlberg, Glenn Chertow, Joseph Liao, Simon Conti, Palo Alto, CA, Christopher Elliott, San Jose, CA, John Leppert, Alan Pao, Palo Alto, CA
Introduction: American Urological Association guidelines recommend 24-hour urine testing in the evaluation and treatment of individuals with high-risk urinary stone disease (USD). However, it remains unknown if clinicians use information from 24-hour urine testing to guide secondary prevention strategies. We sought to determine whether clinicians initiate or discontinue USD-specific medications in response to 24-hour urine testing.
Methods: We used a combination of inpatient or outpatient ICD-9 code for kidney (or ureteral) stone or CPT code for receipt of a kidney (or ureteral) stone procedure to construct a national cohort of stone formers in the Veterans Health Administration between 2007 through 2013. We defined a 24-hour urine test as a 24-hour urine collection for calcium, oxalate, citrate, or sulfate. We compared rates of prescriptions of thiazide or thiazide-type diuretics, alkali therapy, and calcium salts in stone formers who completed at least one 24-hour urine collection and those who did not. We examined rates of prescriptions before and after 24-hour urine collection or initial stone diagnosis (if a stone former did not complete 24-hour urine testing). We also compared rates of prescriptions stratified by 24-hour urine results.
Results: Stone formers who completed 24-hour urine testing had higher rates of prescriptions for thiazide diuretics, alkali therapy, and calcium salts following a 24-hour urine test compared to stone formers who did not complete a 24-hour urine test. Thiazide diuretics were significantly more likely to be prescribed after a 24-hour urine test in patients with hypercalciuria (13.5% increase if urine calcium > 200 mg/day; 1.8% increase if urine calcium < 200 mg/day; p < 0.001); alkali treatment was significantly more likely to be prescribed in patients with hypocitraturia (28.5% increase if urine citrate < 400 mg/day; 8.9% increase if urine citrate > 400 mg/day; p < 0.001); and calcium salts were significantly more likely to be prescribed in stone formers even if they had hypercalciuria or lacked a diagnosis of osteopenia or osteoporosis (1.6% increase if urine calcium > 200 mg/day; 0.6% increase if urine calcium < 200 mg/day; p < 0.001).
Conclusions: Clinicians appear to appropriately adjust their practice patterns by increasing rates of prescription of medications that decrease USD risk in stone formers who complete 24-hour urine testing. However, opportunities exist for clinicians to reduce rates of prescription of medications that may increase stone risk (e.g. calcium salts in stone formers with hypercalciuria).
Source of Funding: NIH/NIDDK