Association of Alternative Approaches to Normalizing Peritoneal Dialysis Clearance with Mortality and Technique Failure: A Retrospective Analysis Using the United States Renal Data System-Dialysis Morbidity and Mortality Study, Wave 2.
♦ BACKGROUND: Total body water (V) is an imprecise metric for normalization of dialytic urea clearance (Kt). This poses a risk of early mortality/technique failure (TF). We examined differences in the distribution of peritoneal Kt/V when V was calculated with actual weight (AW), ideal weight (IW), and adjusted weight (ADW). We also examined the associations of these Kt/V measurements, Kt/body surface area (BSA), and non-normalized Kt with mortality and TF. ♦ METHODS: This is a retrospective cohort study of 534 incident peritoneal dialysis (PD) patients from the Dialysis Morbidity and Mortality Study Wave 2 linked with United States Renal Data System through 2010. Using Cox-proportional hazard models, we examined the relationship of several normalization strategies for peritoneal urea clearance, including Kt/VAW, Kt/VIW, Kt/VADW, Kt/BSA, and non-normalized Kt, with the outcomes of mortality and TF. Harrell's c-statistics were used to assess the relative predictive ability of clearance metrics for mortality and TF. The distributions of Kt/VAW, KT/VIW, and KT/VADWwere compared within and between body mass index (BMI) strata. ♦ RESULTS: Median patient age: 59 (54% male; 72% white; 91% continuous ambulatory PD [CAPD]). Median 24-hour urine volume: 700 mL; median estimated glomerular filtration rate (eGFR) at initiation: 7.15 mL/min/1.73 m2. Technique failure and transplant-censored mortality at 5 years: 37%. Death and transplant-censored TF at 5 years: 60%. There were no significant differences in initial eGFR and 24-hour urine volume across BMI strata. There were statistically significant differences in each Kt/V calculation within the underweight, overweight, and obese strata. After adjustment, there were no significant differences in the hazard ratios (HRs) for TF/mortality for each clearance calculation. Harrell's c-statistics for mortality for each clearance calculation were 0.78, and for TF, 0.60 - 0.61. ♦ CONCLUSIONS: Peritoneal urea clearances are sensitive to subtle changes in the estimation of V. However, there were no detectable significant associations of Kt/VAW, Kt/VIW, Kt/VADW, Kt/BSA, or Kt with TF or mortality.
Drexel University College of Medicine, Philadelphia, PA, USA suzanne.boyle@drexelmed.edu.
Suzanne M
SM
Boyle
University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA.
Yimei
Y
Li
Yale University School of Medicine, New Haven, CT, USA.
F Perry
FP
Wilson
University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA.
Joel D
JD
Glickman
University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA.
Harold I
HI
Feldman
D000328:Adult; D000368:Aged; D001806:Blood Urea Nitrogen; D002423:Cause of Death; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood; D015314:Dialysis Solutions / Q000494:pharmacology; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000009:adverse effects / Q000379:methods / Q000401:mortality*; D016016:Proportional Hazards Models; D012042:Registries; D006435:Renal Dialysis / Q000009:adverse effects / Q000379:methods / Q000401:mortality*; D012189:Retrospective Studies; D018570:Risk Assessment; D016019:Survival Analysis; D014481:United States; D014508:Urea / Q000097:blood*
D015314:Dialysis Solutions; D014508:Urea; D003404:Creatinine
Kt/V; Peritoneal dialysis; adjusted weight; ideal weight; mortality; normalizaton of urea clearance; technique failure; urea clearance
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