Background: Although a relation between the adequacy of hemodialysis and mortality has been established, hemodialysis prescription is rarely individualized precisely in adults with end-stage renal disease in the United States.
Objective: To test whether persons who receive standardized hemodialysis prescriptions have an increased risk for inadequate hemodialysis with increasing body mass.
Design: Cross-sectional study.
Setting: Four ambulatory hemodialysis facilities in Brooklyn, New York.
Patients: 214 patients receiving hemodialysis. Patients were sorted by body weight into quartiles (groups 1 through 4, in ascending order).
Measurements: Urea reduction ratio (percentage reduction in blood urea nitrogen concentration after a hemodialysis session), prescribed length of hemodialysis, and body weight quartile at the start of the study. Urea reduction ratio was measured at the start of the study and at weeks 4, 8, and 12, and a mean value was calculated for each patient. Inadequate hemodialysis was defined by a urea reduction ratio of 65% or less.
Results: Women had a higher mean urea reduction ratio (72% +/- 6%) than men (67.6% +/- 7%) (P < 0.001). The urea reduction ratio was inversely related to body weight (r = -0.47; P = 0.001). It was greater in group 1 (74% +/- 5.2%) than in group 2 (70% +/- 5.7%), group 3 (68% +/- 5.8%), or group 4 (66% +/- 8.4%) (P < 0.05). Logistic regression done with a urea reduction ratio of 65% or less as the outcome variable showed that the odds of receiving inadequate hemodialysis were increased 3.5-fold in men (95% CI, 1.53-fold to 8-fold; P = 0.003), 10-fold in group 3 (CI, 2.1-fold to 50.3-fold; P = 0.003), and 13-fold in group 4 (CI, 2.6-fold to 61.6-fold; P = 0.001).
Conclusions: Standardized hemodialysis prescriptions result in inadequate hemodialysis in many patients who weigh more than 68.2 kg.