Interactions between dialysis-related volume exposures, nutritional surrogates and mortality among ESRD patients.
BACKGROUND
Interdialytic weight gain is used as a surrogate for volume expansion in haemodialysis patients and as an indicator of non-compliance. Increased weight gain is associated with both a greater mortality risk and better nutrition indices. This analysis characterizes the association between dialysis-related volume expansion and mortality in the context of its interaction with nutritional surrogates.


METHODS
All patients receiving haemodialysis through Fresenius Medical Care-North America during 1998 were included. The percentage reduction in weight or intradialytic weight loss (IDWL%) was defined as the difference between the average of pre- and post-dialysis weights from the last 3 months of 1997 expressed as a percentage of post-dialysis weight. Associations between IDWL% and clinical and demographic variables were estimated using linear regression. The association between mortality risk and IDWL% was estimated using Cox proportional hazards regression.


RESULTS
Younger age, male gender, the presence of diabetes mellitus, decreasing cholesterol, post-dialysis weight and pre-dialysis blood pressure (systolic and pulse pressure) were associated with increased IDWL%. Increasing IDWL% was associated with increasing phosphorus, creatinine, albumin, potassium and urea reduction ratio. Increasing IDWL% was significantly associated with mortality at 1 year [hazard ratio (HR) = 1.07, P = 0.003]. Among patients with diabetes mellitus, increasing IDWL% was associated with a mortality HR of 1.03 (P = 0.02). Among patients without diabetes mellitus, increasing IDWL% was not associated with an increased mortality risk. Increasing IDWL% is associated with a greater mortality risk among patients with creatinine <7.26, which failed to remain significant for patients whose creatinine was >or=7.26 mg/dl. Increasing IDWL% is associated with a greater mortality risk among patients with greater post-dialysis weight, greater body mass index and lower serum sodium measurements.


CONCLUSIONS
This study confirms and extends the findings of the deleterious association between increasing IDWL% and mortality among patients with diabetes mellitus and among subgroups based on serum creatinine and body weight. The putative deleterious effect of dialysis-related volume expansion on mortality must be interpreted in the context of the patient's diabetic and nutritional status.
Szczech
Lynda Anne
LA
Department of Medicine, Division of Nephrology, Institute for Renal Outcomes Research and Health Policy, Duke University Medical Center, Durham, NC 27705, USA. scze001@mc.duke.edu
Reddan
Donal N
DN
Klassen
Preston S
PS
Coladonato
Joseph
J
Chua
Benjamin
B
Lowrie
Edmund G
EG
Lazarus
J Michael
JM
Owen
William F
WF
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000097:blood; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000401:mortality* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D016019:Survival Analysis; D015430:Weight Gain
D003404:Creatinine