What is the link between poor ultrafiltration and increased mortality in anuric patients on automated peritoneal dialysis? Analysis of data from EAPOS.
BACKGROUND
Primary analysis of the European Automated Peritoneal Dialysis Outcomes Study (EAPOS) found that patients with daily ultrafiltration (UF) below a predefined target of 750 mL at baseline experienced increased mortality and continuing low UF over 2 years.


METHODS
Multicenter, prospective observational study of prevalent, functionally anuric patients on automated peritoneal dialysis (APD) treated to predefined standards.


METHODS
Secondary data analysis to determine clinical covariates that might support a link between poor UF and outcome, including pattern of comorbidity, prescription, nutrition as determined by Subjective Global Assessment (SGA), membrane function, and blood pressure (BP). Ultrafiltration was treated as a categorical (comparing patients above and below target at baseline) and continuous dependent variable in univariate and multivariate regression. The relationship between BP and survival was also explored.


RESULTS
Of 177 patients recruited from 28 centers across Europe, 43 were below the UF target at baseline. Compared to those above target, there were no differences in the spread of comorbidity, type of APD prescription, SGA, BP, hemoglobin, HCO3, or parathyroid hormone, at baseline or at any later time. At baseline, plasma calcium and, at 12 months, plasma phosphate were lower in the low UF group. There was a weak positive correlation between baseline systolic or diastolic BP and UF, which remained on multivariate analysis but accounted for just 9% of the variability in BP. There was no clear relationship between baseline BP and survival, although, if anything, low BP was associated with earlier death. Poor UF was associated with lower mean dialysate glucose concentration during the first 4 months and with consistently worse membrane function.


CONCLUSIONS
The increased mortality associated with poor UF is likely multifactorial and not easily explained by clear differences in comorbidity, nutritional state, or other indices of treatment at baseline. The lower plasma phosphate suggests a subsequent fall in appetite. Poor BP control is unlikely to be the explanation, and a link between lower BP, reduced UF, and earlier death is suggested. Failure to achieve adequate UF due to worse membrane function remains an important and potentially reversible or preventable cause.
Davies
Simon J
SJ
Department of Nephrology, University Hospital of North Staffordshire, Princes Road, Hartshill, Stoke-on-Trent ST4 7LN, United Kingdom. SimonDavies1@compuserve.com
Brown
Edwina A
EA
Reigel
Werner
W
Clutterbuck
Elaine
E
Heimbürger
Olof
O
Diaz
Nicanor Vega
NV
Mellote
George J
GJ
Perez-Contreras
Javier
J
Scanziani
Renzo
R
D'Auzac
Christian
C
Kuypers
Dirk
D
Divino Filho
Jose C
JC
D001002:Anuria / Q000401:mortality*; D001331:Automation; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010530:Peritoneal Dialysis / Q000401:mortality / Q000706:statistics & numerical data*; D016019:Survival Analysis; D016896:Treatment Outcome
D001786:Blood Glucose