Mortality risk for dialysis patients with different levels of serum calcium, phosphorus, and PTH: the Dialysis Outcomes and Practice Patterns Study (DOPPS).
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.


METHODS
Prospective cohort study.


METHODS
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).


METHODS
Serum calcium, albumin-corrected calcium (Ca(Alb)), phosphorus, and PTH levels.


RESULTS
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.


CONCLUSIONS
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.
Arbor Research Collaborative for Health, University of Michigan, Ann Arbor, MI 48103, USA. francesca.tentori@ArborResearch.org
Francesca
F
Tentori
Margaret J
MJ
Blayney
Justin M
JM
Albert
Brenda W
BW
Gillespie
Peter G
PG
Kerr
Jürgen
J
Bommer
Eric W
EW
Young
Tadao
T
Akizawa
Takashi
T
Akiba
Ronald L
RL
Pisoni
Bruce M
BM
Robinson
Friedrich K
FK
Port
D000368:Aged; D044362:Australasia; D002118:Calcium / Q000097:blood*; D015331:Cohort Studies; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009656:North America / Q000453:epidemiology; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000097:blood*; D016016:Proportional Hazards Models; D006435:Renal Dialysis / Q000009:adverse effects* / Q000401:mortality*; D018570:Risk Assessment; D016019:Survival Analysis
C470125:PTH protein, human; D010281:Parathyroid Hormone; D010758:Phosphorus; D002118:Calcium