Longitudinal associations between dietary protein intake and survival in hemodialysis patients.
BACKGROUND
Decreased dietary protein intake may be associated with increased mortality risk in individuals with kidney failure undergoing maintenance hemodialysis (MHD). We hypothesized that longitudinal changes in dietary protein intake have independent associations with survival in MHD patients.


METHODS
The relation between urea kinetic-based normalized protein nitrogen appearance (nPNA) and all-cause and cardiovascular mortality was examined in a 2-year (July 2001 to June 2003) cohort of 53,933 MHD patients from virtually all DaVita dialysis clinics in the United States, using both conventional and time-dependent (repeated-measure) Cox models to estimate death hazard ratios for quarterly averaged nPNA categories controlled for case-mix, comorbidity, dialysis dose (Kt/V), and available markers of malnutrition-inflammation complex syndrome (MICS).


RESULTS
The best survival was associated with nPNA between 1.0 and 1.4 g/kg/d, whereas nPNA less than 0.8 or greater than 1.4 g/kg/d was associated with greater mortality in almost all models. Adjustment for MICS mitigated the associations substantially. A decrease in protein intake during the first 6 months in patients with an nPNA in the 0.8- to 1.2-g/kg/d range was associated incrementally with greater death risks in the subsequent 18 months, whereas an increase in nPNA tended to correlate with reduced death risk.


CONCLUSIONS
Low daily protein intake or decrease in its magnitude over time is associated with increased risk for death in MHD patients. Whether the association between time-varying protein intake and survival is causal or a consequence of anorexia secondary to MICS or other factors needs to be explored further in interventional trials.
Shinaberger
Christian S
CS
Division of Nephrology and Hypertension, Los Angeles Biomedical Institute at Harbor-UCLA Medical Center, Torrance, CA 90509-2910, USA.
Kilpatrick
Ryan D
RD
Regidor
Deborah L
DL
McAllister
Charles J
CJ
Greenland
Sander
S
Kopple
Joel D
JD
Kalantar-Zadeh
Kamyar
K
D000368:Aged; D002318:Cardiovascular Diseases / Q000209:etiology / Q000401:mortality*; D004044:Dietary Proteins; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D009752:Nutritional Status; D011379:Prognosis; D006435:Renal Dialysis; D051437:Renal Insufficiency / Q000150:complications / Q000628:therapy*; D012307:Risk Factors; D016019:Survival Analysis; D014508:Urea / Q000378:metabolism
D004044:Dietary Proteins; D014508:Urea; D009584:Nitrogen