Dialysis – Transplantation

Kidney International (2005) 67, 1179–1187; doi:10.1111/j.1523-1755.2005.00185.x

Predictors and consequences of altered mineral metabolism: The Dialysis Outcomes and Practice Patterns Study

ERIC W YOUNG, JUSTIN M ALBERT, SUDTIDA SATAYATHUM, DAVID A GOODKIN, RONALD L PISONI, TAKASHI AKIBA, TADAO AKIZAWA, KIYOSHI KUROKAWA, JÜRGEN BOMMER, LUIS PIERA and FRIEDRICH K PORT

Department of Veterans Affairs Medical Center, and Division of Nephrology, University of Michigan, Ann Arbor, Michigan; University Renal Research and Education Association (URREA), Ann Arbor, Michigan; ICOS Corporation, Bothell, Washington; Department of Blood Purification and Internal Medicine, Tokyo Women's Medical University, Tokyo, Japan; Center of Blood Purification Therapy, Wakayama Medical University, Wakayama, Japan; Institute of Medical Science, Tokai University, Kanagawa, Japan; University of Heidelberg, Heidelberg, Germany; and Nephrology Service, Hospital General Vall d'Hebron, Barcelona, Spain

Correspondence: Eric W. Young, M.D., c/o URREA 315 W. Huron, Suite 260, Ann Arbor, MI 48103. E-mail:DOPPS@urrea.org

Received 11 May 2004; Revised 4 August 2004; Accepted 7 October 2004.

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Abstract

Predictors and consequences of altered mineral metabolism: The Dialysis Outcomes and Practice Patterns Study.

Background

 

Altered mineral metabolism contributes to bone disease, cardiovascular disease, and other clinical problems in patients with end-stage renal disease.

Methods

 

This study describes the recent status, significant predictors, and potential consequences of abnormal mineral metabolism in representative groups of hemodialysis facilities (N = 307) and patients (N = 17,236) participating in the Dialysis Outcomes and Practice Patterns Study (DOPPS) in the United States, Europe, and Japan from 1996 to 2001.

Results

 

Many patients fell out of the recommended guideline range for serum concentrations of phosphorus (8% of patients below lower target range, 52% of patients above upper target range), albumin-corrected calcium (9% below, 50% above), calcium-phosphorus product (44% above), and intact PTH (51% below, 27% above). All-cause mortality was significantly and independently associated with serum concentrations of phosphorus (RR 1.04 per 1 mg/dL, P = 0.0003), calcium (RR 1.10 per 1 mg/dL, P < 0.0001), calcium-phosphorus product (RR 1.02 per 5 mg2/dL2, P = 0.0001), PTH (1.01 per 100 pg/dL, P = 0.04), and dialysate calcium (RR 1.13 per 1 mEq/L, P = 0.01). Cardiovascular mortality was significantly associated with the serum concentrations of phosphorus (RR 1.09, P < 0.0001), calcium (RR 1.14, P < 0.0001), calcium-phosphorus product (RR 1.05, P < 0.0001), and PTH (RR 1.02, P = 0.03). The adjusted rate of parathyroidectomy varied 4-fold across the DOPPS countries, and was significantly associated with baseline concentrations of phosphorus (RR 1.17, P < 0.0001), calcium (RR 1.58, P < 0.0001), calcium-phosphorus product (RR 1.11, P < 0.0001), PTH (RR 1.07, P < 0.0001), and dialysate calcium concentration (RR 0.57, P = 0.03). Overall, 52% of patients received some form of vitamin D therapy, with parenteral forms almost exclusively restricted to the United States. Vitamin D was potentially underused in up to 34% of patients with high PTH, and overused in up to 46% of patients with low PTH. Phosphorus binders (mostly calcium salts during the study period) were used by 81% of patients, with potential overuse in up to 77% patients with low serum phosphorus concentration, and potential underuse in up to 18% of patients with a high serum phosphorus concentration.

Conclusion

 

This study expands our understanding of the relationship between altered mineral metabolism and outcomes and identifies several potential opportunities for improved practice in this area.

Keywords:

mineral metabolism, vitamin D, phosphorus binders, calcium-phosphorus product, parathyroid hormone, DOPPS

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