Serum iPTH, calcium and phosphate, and the risk of mortality in a European haemodialysis population.
BACKGROUND
A number of US observational studies reported an increased mortality risk with higher intact parathyroid hormone (iPTH), calcium and/or phosphate. The existence of such a link in a European haemodialysis population was explored as part of the Analysing Data, Recognising Excellence and Optimising Outcomes (ARO) Chronic Kidney Disease (CKD) Research Initiative.


METHODS
The association between the markers of mineral and bone disease and clinical outcomes was examined in 7970 patients treated in European Fresenius Medical Care facilities over a median of 21 months. Baseline and time-dependent (TD) Cox regression were performed using Kidney Disease Outcomes Quality Initiative (KDOQI) target ranges as reference categories, adjusting for demographics, medical history, dialysis parameters, inflammation, medications and laboratory parameters. Fractional polynomial (FP) models were also used.


RESULTS
Hazard ratio (HR) estimates from baseline analysis for iPTH were U-shaped [>600 pg/mL, HR = 2.10, 95% confidence interval (CI) 1.62-2.73; <75 pg/mL, HR = 1.46, 95% CI 1.17-1.83]. TD analysis confirmed the results for iPTH. Baseline analysis showed that calcium >2.75 mmol/L increased risk of death (HR = 1.70, 95% CI 1.19-2.42). TD analysis showed that both low (HR = 1.19, 95% CI 1.04-1.37) and high calcium (HR = 1.74, 95% CI 1.30-2.34) increased risk of death. Baseline analysis for phosphate showed a U-shaped pattern (<1.13 mmol/L, HR = 1.18, 95% CI 1.01-1.37; >1.78 mmol/L, HR = 1.32, 95% CI 1.13-1.55). TD analysis confirmed the results for phosphate <1.13 mmol/L. HR estimates were higher in patients with diabetes versus those without diabetes for baseline analysis only (P-value = 0.014). FP analysis confirmed the results of baseline and TD analyses.


CONCLUSIONS
Patients with iPTH, calcium and phosphate levels within the KDOQI target ranges have the lowest risk of mortality compared with those outside the target ranges.
Floege
Jürgen
J
Div. Nephrology, RWTH University of Aachen, Germany. juergen.floege@rwth-aachen.de
Kim
Joseph
J
Ireland
Elizabeth
E
Chazot
Charles
C
Drueke
Tilman
T
de Francisco
Angel
A
Kronenberg
Florian
F
Marcelli
Daniele
D
Passlick-Deetjen
Jutta
J
Schernthaner
Guntram
G
Fouqueray
Bruno
B
Wheeler
David C
DC
D000368:Aged; D001851:Bone Diseases, Metabolic / Q000097:blood / Q000401:mortality; D002118:Calcium / Q000097:blood*; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood; D005060:Europe; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D008903:Minerals / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000097:blood*; D006435:Renal Dialysis / Q000401:mortality*; D015996:Survival Rate
D008903:Minerals; D010281:Parathyroid Hormone; D010758:Phosphorus; D003404:Creatinine; D002118:Calcium
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