Association of cumulatively low or high serum calcium levels with mortality in long-term hemodialysis patients.
BACKGROUND
The outcome-predictability of baseline and instantaneously changing serum calcium in hemodialysis patients has been examined. We investigated the mortality-predictability of time-averaged calcium values to reflect the 'cumulative' effect of calcium burden over time.


METHODS
We employed a Cox model using up-to-5-year (7/2001-6/2006) time-averaged values to examine the mortality-predictability of cumulative serum calcium levels in 107,200 hemodialysis patients prior to the use of calcimimetics, but during the time where other calcium-lowering interventions, including lower dialysate calcium, were employed.


RESULTS
Both low (<9.0 mg/dl) and high (>10.0 mg/dl) calcium levels were associated with increased mortality (reference: 9.0 to <9.5 mg/dl). Whereas mortality of hypercalcemia was consistent, hypocalcemia mortality was most prominent with higher serum phosphorus (>3.5 mg/dl) and PTH levels (>150 pg/ml). Higher paricalcitol doses shifted the calcium range associated with the greatest survival to the right, i.e. from 9.0 to <9.5 to 9.5 to <10.0 mg/dl. African-Americans exhibited the highest death hazard ratio of hypocalcemia <8.5 mg/dl, being 1.35 (95% CI: 1.22-1.49). Both a rise and drop in serum calcium over 6 months were associated with increased mortality compared to the stable group.


CONCLUSIONS
Whereas in hemodialysis patients cumulatively high or low calcium levels are associated with higher death risk, subtle but meaningful interactions with phosphorus, PTH, paricalcitol dose and race exist.
Miller
Jessica E
JE
Harold Simmons Center for Kidney Disease Research and Epidemiology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90509-2910, USA.
Kovesdy
Csaba P
CP
Norris
Keith C
KC
Mehrotra
Rajnish
R
Nissenson
Allen R
AR
Kopple
Joel D
JD
Kalantar-Zadeh
Kamyar
K
D000328:Adult; D001741:Black or African American; D000368:Aged; D050071:Bone Density Conservation Agents / Q000008:administration & dosage; D002423:Cause of Death; D004872:Ergocalciferols / Q000008:administration & dosage; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000150:complications* / Q000208:ethnology; D006996:Hypocalcemia / Q000150:complications* / Q000208:ethnology; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000208:ethnology / Q000401:mortality*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D013997:Time Factors
D050071:Bone Density Conservation Agents; D004872:Ergocalciferols; D010281:Parathyroid Hormone; C084656:paricalcitol
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