Kidney Week

Abstract: FR-PO236

Comparison of Thiazide vs. Alkali Citrate for Kidney Stone Recurrence among Individuals with Hypocitraturia and High Urine pH

Session Information

• Mineral Bone Disease: Transplant and Kidney Stones
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Bone and Mineral Metabolism

• 502 Bone and Mineral Metabolism: Clinical

Authors

• Hsi, Ryan, Vanderbilt University Medical Center, Nashville, Tennessee, United States

Ryan Hsi, MD

• Oerline, Mary K., University of Michigan, Ann Arbor, Michigan, United States

Mary K. Oerline, MS

• Crivelli, Joseph J., University of Alabama, Birmingham, Alabama, United States

Joseph J. Crivelli, MD

• Best, Sara L., Laboratory Corporation of America Holdings, Burlington, North Carolina, United States

Sara L. Best, MD

• Asplin, John R., Laboratory Corporation of America Holdings, Burlington, North Carolina, United States

John R. Asplin, MD, FASN

• Shahinian, Vahakn, University of Michigan, Ann Arbor, Michigan, United States

Vahakn Shahinian, MD

• Hollingsworth, John M., NorthShore University HealthSystem, Evanston, Illinois, United States

John M. Hollingsworth, MD, MS

Background

The comparative effectiveness of thiazide versus alkali citrate for the prevention of kidney stone recurrence is unknown among individuals with low urinary citrate and high urine pH. We sought to compare symptomatic stone recurrence among individuals with low urinary citrate and high urine pH prescribed thiazides versus alkali citrate.

Methods

Among Medicare beneficiaries with a 24-hour urine collection obtained between 2010 and 2019, we identified individuals with hypocitraturia (≤300 mg/day for males and ≤350 mg/day for females) and high urine pH (>6.3) who had not received thiazides or alkali citrate in the 6 months prior to the collection. Then, we identified a subset who subsequently received a prescription fill for a thiazide or alkali citrate, but not both, within 6 months after the urine collection. We used the Kaplan-Meier method and multivariable Cox modeling, adjusting for demographic and baseline 24-hour urine parameters to compare the incidence of a symptomatic stone event (i.e., an emergency department visit, hospitalization, or surgery for kidney stones) by 3 years after initiating medical therapy.

Results

Among 1270 individuals (mean age 62.8 years and 68% female), we identified 107 and 1163 people receiving thiazides and alkali citrate, respectively. Comparing those prescribed thiazides versus alkali citrate, we found baseline differences in mean 24-hour urinary citrate (195 mg vs 171 mg, p=0.01) and calcium (209 mg vs 151 mg, p<0.001), but not urine pH (6.7 for both groups). The unadjusted cumulative incidence of a symptomatic stone event was 23.8% for the thiazide group and 33.6% for the alkali citrate group at 3 years (p<0.05). Compared to alkali citrate, thiazide use was associated with a significantly lower hazard of a symptomatic stone event (HR=0.645, 95% CI 0.429-0.970, p=0.04). A sensitivity analysis matching thiazide to alkali citrate users 1:1 by baseline calcium and citrate (n=200) showed similar results (HR=0.445, 95% CI 0.257-0.770, p<0.01).

Conclusion

Compared to alkali citrate, thiazides were associated with a reduction in symptomatic stone events among individuals with hypocitraturia and high urine pH. These data suggest that a prospective trial is warranted to compare their effectiveness.

Funding

• NIDDK Support