Peritoneal Protein Clearance and not Peritoneal Membrane Transport Status Predicts Survival in a Contemporary Cohort of Peritoneal Dialysis Patients

Abstract

Background and objectives: Fast peritoneal membrane transport status may be due to inflammation or increased peritoneal membrane surface area. We evaluated the ability of peritoneal protein clearance (Pcl) to distinguish fast peritoneal membrane transport status as a consequence of peritoneal membrane inflammation and assess its impact on patient survival.Design, setting, participants, & measurements: Patients who initiated peritoneal dialysis at our center since January 1998 and had a baseline peritoneal equilibration test, measurement of dialysis adequacy, and 24-h dialysate Pcl were included. Demography, comorbidities, and biochemical data were prospectively collected. Follow-up was until death or the end of the period studied. Multivariate regression analysis identified factors that were associated with Pcl. A Cox proportional hazards model was used to identify factors that were associated with survival.Results: A total of 192 patients (56% men, mean age 54.3 ؎ 15.3; 32% with diabetes) were included. On univariate analysis, Pcl was negatively correlated with serum albumin and positively correlated with age, dialysate/plasma creatinine ratio (D/Pcr), the presence of peripheral vascular disease, and urine volume. On multivariate analysis, serum albumin, D/Pcr, urine volume, and peripheral vascular disease remained significant. Predictors of mortality were age, comorbidity grade, and Pcl but not D/Pcr.Conclusions: In this cohort, peritoneal transport status no longer predicted survival, whereas Pcl remained a predictor. Increased large-pore protein loss may reflect the severity of underlying cardiovascular disease, portending a poor prognosis for these patients.

Peritoneal Albumin and Protein Losses Do Not Predict Outcome in Peritoneal Dialysis Patients

“…Similar results were found when albumin clearances were replaced by albumin loss or by clearances of ␤ 2 m, IgG, and ␣ 2 m. The latest findings show that PVD-a marker of cardiovascular disease and mortality in chronic kidney disease patients (27)-is associated with increased peritoneal transport of macromolecules in general and is not specific for albumin. It also implies that an analogy with microalbuminuria, as has been suggested in some studies (17)(18)(19), is very unlikely. All of the above data support the hypothesis that peritoneal transport of macromolecules is high in patients with an inherent fast transport status, which can be due to either inflammatory mediators like IL-6 or the presence of a large mesothelial cell mass, which is expressed by high CA125 levels (28).…”

“…Since 2002 studies have been published on peritoneal transport of total protein and its association with patient comorbidity and survival (17)(18)(19)(20)(21)(22). These studies postulate that protein leak across the membrane (like small molecules transport) may be increased by systemic inflammation and therefore may be a mor-…”

Plasma Volume, Albumin, and Fluid Status in Peritoneal Dialysis Patients

“…Using this approach, the most recent analysis indicates that peritoneal membrane transport characteristics do not influence patient survival (7). As part of routine clinical assessment, membrane function and adequacy, including sodium removal, is measured at least every 6 months.…”

“…It is not clear, however, whether this association is causal, with excess tissue hydration or expanded plasma volume (PV) accelerating organ dysfunction, or simply evidence that there are difficulties in achieving euvolemia due to confounding factors such as cardiac dysfunction, inflammation, or poor dietary intake (3)(4)(5). Individual variability in peritoneal membrane function may also contribute to this problem, although there is now increasing evidence that poor ultrafiltration associated with high solute transport rates can be avoided by using automated PD and icodextrin (6,7).…”

Longitudinal Study of Small Solute Transport and Peritoneal Protein Clearance in Peritoneal Dialysis Patients

“…This is further confused by the observation that peritoneal protein clearance (Pcl) is associated with increased age and comorbidity at the start of treatment. Moreover, in some (8,(11)(12)(13)(14) but not all (15) studies it is an independent predictor of survival, resulting in the potential confounding of longitudinal data due to earlier dropout of patients with high Pcl (informative censoring).…”