Mortality Risk for Dialysis Patients With Different Levels of Serum Calcium, Phosphorus, and PTH: The Dialysis Outcomes and Practice Patterns Study (DOPPS)

Tentori, Francesca; Blayney, Margaret J.; Albert, Justin M.; Gillespie, Brenda W.; Kerr, Peter G.; Bommer, Jürgen; Young, Eric W.; Akizawa, Tadao; Akiba, Takashi; Pisoni, Ronald L.; Robinson, Bruce M.; Port, Friedrich K.

doi:10.1053/j.ajkd.2008.03.020

« Previous Next »American Journal of Kidney Diseases
Volume 52, Issue 3 , Pages 519-530, September 2008

Mortality Risk for Dialysis Patients With Different Levels of Serum Calcium, Phosphorus, and PTH: The Dialysis Outcomes and Practice Patterns Study (DOPPS)

Francesca Tentori, MD
- Arbor Research Collaborative for Health, University of Michigan, Ann Arbor, MI
- Address correspondence to Francesca Tentori, MD, Arbor Research Collaborative for Health, 315 W Huron St, Ste 360, Ann Arbor, MI 48103
Margaret J. Blayney, MS
- Arbor Research Collaborative for Health, University of Michigan, Ann Arbor, MI
Justin M. Albert, BA
- Arbor Research Collaborative for Health, University of Michigan, Ann Arbor, MI
Brenda W. Gillespie, PhD
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, MI
Peter G. Kerr, MBBS, PhD, FRACP
- Monash Medical Centre/Monash University, Clayton, Victoria, Australia
Jürgen Bommer, MD
- University of Heidelberg, Heidelberg, Germany
Eric W. Young, MD, MS
- Veterans Affairs Medical Center/University of Michigan, Ann Arbor, MI
Tadao Akizawa, MD
- Showa University, Tokyo, Japan
Takashi Akiba, MD
- Tokyo Women's Medical University, Tokyo, Japan
Ronald L. Pisoni, PhD
- Arbor Research Collaborative for Health, University of Michigan, Ann Arbor, MI
Bruce M. Robinson, MD, MS
- Arbor Research Collaborative for Health, University of Michigan, Ann Arbor, MI
Friedrich K. Port, MD, MS
- Arbor Research Collaborative for Health, University of Michigan, Ann Arbor, MI

Received 16 October 2007; accepted 24 March 2008. published online 03 June 2008.

Background

Abnormalities in serum calcium, phosphorus, and parathyroid hormone (PTH) concentrations are common in patients with chronic kidney disease and have been associated with increased morbidity and mortality. No clinical trials have been conducted to clearly identify categories of calcium, phosphorus, and PTH levels associated with the lowest mortality risk. Current clinical practice guidelines are based largely on expert opinions, and clinically relevant differences exist among guidelines across countries. We sought to describe international trends in calcium, phosphorus, and PTH levels during 10 years and identify mortality risk categories in the Dialysis Outcomes and Practice Patterns Study (DOPPS), an international study of hemodialysis practices and associated outcomes.

Study Design

Prospective cohort study.

Participants

25,588 patients with end-stage renal disease on hemodialysis therapy for longer than 180 days at 925 facilities in DOPPS I (1996-2001), DOPPS II (2002-2004), or DOPPS III (2005-2007).

Predictors

Serum calcium, albumin-corrected calcium (Ca_Alb), phosphorus, and PTH levels.

Outcomes

Adjusted hazard ratios for all-cause and cardiovascular mortality calculated using Cox models.

Results

Distributions of mineral metabolism markers differed across DOPPS countries and phases, with lower calcium and phosphorus levels observed in the most recent phase of DOPPS. Survival models identified categories with the lowest mortality risk for calcium (8.6 to 10.0 mg/dL), Ca_Alb (7.6 to 9.5 mg/dL), phosphorus (3.6 to 5.0 mg/dL), and PTH (101 to 300 pg/mL). The greatest risk of mortality was found for calcium or Ca_Alb levels greater than 10.0 mg/dL, phosphorus levels greater than 7.0 mg/dL, and PTH levels greater than 600 pg/mL and in patients with combinations of high-risk categories of calcium, phosphorus, and PTH.

Limitations

Because of the observational nature of DOPPS, this study can only indicate an association between mineral metabolism categories and mortality.

Conclusions

Our results provide important information about mineral metabolism trends in hemodialysis patients in 12 countries during a decade. The risk categories identified in the DOPPS cohort may be relevant to efforts at international harmonization of existing clinical guidelines for mineral metabolism.

Index Words: Hemodialysis, mineral metabolism, cardiovascular disease, guidelines, Dialysis Outcomes and Practice Patterns Study (DOPPS)