Kidney Week

Abstract: SA-PO674

Twenty-Four Hour Urine Testing in Kidney Stone Formers: A Veterans Health Administration Study

Session Information

• Bone and Mineral Metabolism: Clinical - II
  October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Bone and Mineral Metabolism

• 402 Bone and Mineral Metabolism: Clinical

Authors

• Ganesan, Calyani, Stanford Nephrology, Redwood City, California, United States

Calyani Ganesan,

• Thomas, I-Chun, VA Palo Alto, PALO ALTO, California, United States

I-Chun Thomas,

• Sun, Andrew J., Stanford University, Palo Alto, California, United States

Andrew J. Sun,

• Conti, Simon, Stanford, San Jose, California, United States

Simon Conti,

• Elliott, Christopher S., Stanford, San Jose, California, United States

Christopher S. Elliott,

• Liao, Joseph C., Stanford University, Palo Alto, California, United States

Joseph C. Liao,

• Kurella Tamura, Manjula, Stanford University, Palo Alto, California, United States

Manjula Kurella Tamura,

• Chertow, Glenn Matthew, Stanford University School of Medicine, Palo Alto, California, United States

Glenn Matthew Chertow,

• Leppert, John, Stanford University, Palo Alto, California, United States

John Leppert,

• Pao, Alan C., Stanford University, Palo Alto, California, United States

Alan C. Pao,

Background

The American Urological Association recommends 24-hour urine testing in stone formers to prevent recurrent stones. However national practice patterns of metabolic evaluation which utilize urine testing remain uncharacterized. To address this, we identified stone formers in the national Veterans Health Administration (VHA) database and assessed the characteristics of those who received 24-hour urine testing and the timing and frequency of testing.

Methods

We defined stone formers as those with one or more inpatient ICD-9 codes for stones, two or more outpatient ICD-9 codes for stones, or one or more CPT codes for stone procedures in 2007-13 using the national VHA database. We defined a 24-hour urine test as having a 24-hour urine calcium, oxalate, citrate or sulfate measurement. We compared demographics and clinical characteristics among Veterans who received testing and those who did not. We determined the timing and frequency of 24-hour urine testing and evaluated whether urine testing varied geographically. We assessed factors associated with 24-hour testing using multivariable regression.

Results

We identified 130,489 individuals with a stone encounter between 2007-2013. Within this stone cohort, 13.3% (19,288 individuals) underwent 24-hour urine testing. These individuals were younger, had fewer comorbidities, and were more likely to be seen on an outpatient basis. In addition, those with 24-hour urine testing had more stone procedures than those who did not (3.0 + 2.8 vs. 2.3 + 2.1, p <.001). The majority of testing occurred within 1 year of a stone encounter. There was considerable geographic variation in the utilization of 24-hour urine tests, ranging between 1% and 40% across VA facilities, with the most frequent testing in the western United States.

Conclusion

We found high facility level variation in 24-hour urine testing among stone formers. Our results suggest that in addition to patient risk, physician practice patterns influence the use of 24-hour testing in urinary stone disease. Comparative effectiveness research could help to define the role of 24-hour urine testing in the evaluation and management of kidney stones.

Funding

• Private Foundation Support