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Kidney Week

Abstract: FR-PO155

Mortality Risk with Serum Phosphorous in Twice-Weekly vs. Thrice-Weekly Hemodialysis Patients

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Wenziger, Cachet, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Aguirre, Antonio, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Park, Christina, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Hsiung, Jui-Ting, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Kovesdy, Csaba P., University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Kalantar-Zadeh, Kamyar, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Rhee, Connie, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Streja, Elani, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
Background

Patients on dialysis commonly have abnormally elevated serum phosphorous levels. Both high and low serum phosphorous have been associated with greater mortality risk in thrice weekly incident hemodialysis (HD) patients. However, less is known about this relationship in patients undergoing twice weekly HD. This study examines the phosphorous-mortality relationship in twice weekly compared to thrice weekly HD patients.

Methods

From a large national dialysis cohort of incident HD patients (2007-2011), we identified 78,849 thrice weekly and 3,989 twice weekly HD patients. For each dialysis type, patients were divided into four groups of phosphorous levels: <3.5, 3.5-<5.5 [ref.], 5.5-<7 and ≥7 mg/dL. We examined the association of phosphorous levels and all-cause mortality using Cox models adjusted for case-mix and markers of malnutrition and inflammation.

Results

In thrice and twice weekly patients respectively, the mean age was 63 ± 15 and 68 ± 14 years, 43% and 47% were female, 31% and 15% were African American. Higher phosphorous was associated with a higher mortality risk in both twice and thrice weekly patients; however, the risk appeared stronger for twice weekly [Figure]. Lower phosphorous was not associated with any difference in mortality risk compared to the reference group, while it appeared to trend toward lower mortality risk in twice weekly HD patients. The p-for-interaction was 0.02 indicative of a significant effect of dialysis type on the phosphorous-mortality relationship.

Conclusion

The relationship of phosphorous and mortality differs in patients receiving twice and thrice weekly HD treatment. Patients with lower phosphorous levels receiving twice weekly HD treatment overall had lower mortality rates compared to thrice weekly HD patients.

Funding

  • NIDDK Support