Serum alkaline phosphatase and phosphate and risk of mortality and hospitalization.
OBJECTIVE
Elevated alkaline phosphatase (AlkPhos) and phosphate levels are associated with cardiovascular morbidity and mortality in patients receiving dialysis. A retrospective cohort study was conducted to test these associations in outpatients with an estimated GFR > or =60 ml/min/1.73 m(2).


METHODS
Patients with serum AlkPhos and phosphate levels measured between 2000 and 2002 (n = 10,743) at Montefiore Medical Center (MMC) clinics were followed through September 11, 2008 (median 6.8 years). Mortality data were obtained via Social Security Administration records (n = 949 deaths). Hospitalization data were obtained from MMC records.


RESULTS
The mean age was 51 years, 64% were women, 22% were white, 26% were non-Hispanic black, 16% were Hispanic, 13% had a diagnosis of hypertension, 9% had diabetes mellitus, and 8% had cardiovascular disease at baseline. AlkPhos and phosphate were independently associated with mortality and cardiovascular-related hospitalization after multivariable adjustment. Comparing patients in the highest (> or =104 U/L) versus lowest quartile of AlkPhos (< or =66 U/L), the adjusted hazard ratio (HR) for mortality was 1.65 (P trend across quartiles <0.001). For the highest compared with the lowest quartile of serum phosphate (> or =3.8 mg/dl versus < or =3.0 mg/dl), the adjusted HR for mortality was 1.29 (P trend across quartiles = 0.008). High AlkPhos but not phosphate levels were also associated with all-cause, infection-related, and fracture-related hospitalization.


CONCLUSIONS
Higher levels of serum AlkPhos and phosphate were associated with increased mortality and cardiovascular-related hospitalization in an inner-city clinic population. Further studies are needed to elucidate mechanisms underlying these associations.
Abramowitz
Matthew
M
Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York, USA. matthew.abramowitz@einstein.yu.edu
Muntner
Paul
P
Coco
Maria
M
Southern
William
W
Lotwin
Irwin
I
Hostetter
Thomas H
TH
Melamed
Michal L
ML
D000328:Adult; D000368:Aged; D000469:Alkaline Phosphatase / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology / Q000401:mortality*; D016009:Chi-Square Distribution; D005260:Female; D005919:Glomerular Filtration Rate; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications / Q000401:mortality* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009519:New York City / Q000453:epidemiology; D010710:Phosphates / Q000097:blood*; D016016:Proportional Hazards Models; D006435:Renal Dialysis / Q000009:adverse effects / Q000401:mortality*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D015854:Up-Regulation; D014505:Urban Population / Q000706:statistics & numerical data
D015415:Biomarkers; D010710:Phosphates; D000469:Alkaline Phosphatase