Dialysis vintage, body composition, and survival in peritoneal dialysis patients.

The relationship between dialysis vintage (length of time on dialysis), body composition, and survival has been reported in hemodialysis patients. In the present study, we examined the association ofdialysis vintage with body composition and survival in peritoneal dialysis (PD) patients. At enrollment, body composition in 65 PD patients was determined by bioelectrical impedance analysis. Patients (mean age at enrollment: 54 years) were followed for up to 11 years maximum. At enrollment, the mean, median, and maximum dialysis vintages were 51, 34, and 261 months respectively. After adjusting for age, race, sex, and diabetes status, dialysis vintage was indirectly correlated (partial correlation coefficients) with body weight (r = -0.40, p = 0.001), body mass index (r = -0.40, p = 0.002), body surface area (r = -0.39, p = 0.002), body cell mass (r = -0.39, p = 0.002), total body fat weight (r = -0.30, p = 0.02), and fat percentage of body weight (r = -0.31, p = 0.018), and directly correlated with extracellular mass to body cell mass ratio (r = 0.27, p = 0.039). The observed cumulative survival was significantly higher (p = 0.007) in patients with a dialysis vintage at enrollment of 35 months or less, than in patients with dialysis vintage at enrollment of more than 35 months. In the multivariate Cox regression analysis, adjusting for age, race, sex, and diabetes, dialysis vintage at enrollment remained an independent predictor of mortality (relative risk: 1.010; p = 0.002). Increase in relative risk of death with increasing dialysis vintage may be partly explained by the association of vintage with unfavorable changes in body composition and the nutrition status of patients over time.

Extracellular mass/body cell mass ratio is an independent predictor of survival in peritoneal dialysis patients.

Malnutrition is a strong predictor of mortality in peritoneal dialysis (PD) patients. Extracellular mass (ECM) contains all the metabolically inactive, whereas body cell mass (BCM) contains all the metabolically active, tissues of the body. ECM/BCM ratio is a highly sensitive index of malnutrition. The objective of this study was to explore the relationship between ECM/BCM ratio and survival in PD patients. We enrolled 62 patients from November 2000 to July 2008. On enrollment, demographic, clinical, and biochemical data were recorded. Bioimpedance analysis (BIA) was used to determine ECM and BCM in PD patients. Patients were followed up to November 2008. Mean age was 54+/-16 (s.d.) years; female, 55%; African Americans, 65%; diabetic, 24%. Mean ECM/BCM ratio was 1.206+/-0.197 (range: 0.73-1.62). Diabetics had higher ECM/BCM ratio than nondiabetics (1.29 vs 1.18, P=0.04). ECM/BCM ratio correlated directly with age (r=0.38, P=0.002) and inversely with serum albumin (r=-0.43, P=0.001), creatinine (-0.24, P=0.08), blood urea nitrogen (r=-0.26, P=0.06), and total protein (r=-0.31, P=0.026). Using multivariate Cox regression analysis, adjusting for age, race, gender, diabetes, and human immunodeficiency virus status, enrollment ECM/BCM ratio was a significant independent predictor of mortality (relative risk=1.035, P=0.018). For every 10% increase in the ECM/BCM ratio, the relative risk of death was increased by about 35%. In conclusion, BIA-derived enrollment ECM/BCM ratio, a marker of malnutrition, was an independent predictor of long-term survival in PD patients.

Relationship of serum magnesium to body composition and inflammation in peritoneal dialysis patients.

Magnesium is one of the most abundant cations in the body and is involved in many cell functions. Serum magnesium concentration is maintained within a narrow range by the kidney and digestive tract. It has been reported that a lower serum magnesium level is a significant predictor for mortality in hemodialysis patients. Body composition and inflammation are important predictors of mortality in peritoneal dialysis (PD) patients. The objective of the present study was to examine the relationship of serum magnesium with body composition and inflammation in PD patients. Our study enrolled 62 PD patients treated at the Long Island College Hospital between November 2000 and July 2008. Demographic, clinical, and biochemical data were recorded. Body composition parameters were determined by bioelectrical impedance analysis (BIA). High sensitivity C-reactive protein (hs-CRP), a marker of inflammation was measured by the immunoturbidimetric method. In these patients (mean age: 55 years; 63% African American; 55% women; 25% with diabetes), the mean (+/- standard deviation) serum magnesium and hs-CRP were 1.597 +/- 0.28 mEq/L and 13.70 +/- 21 mg/L respectively. Serum magnesium was directly correlated with serum markers of nutrition: albumin (r = 0.42, p = 0.001), creatinine (r = 0.43, p = 0.0001), and total protein (r = 0.44, p < 0.0001). Serum magnesium was also directly correlated with phase angle, a BIA parameter and marker of cellular health (correlation coefficient: r = 0.35; p = 0.006), and inversely correlated with the extracellular mass/body cell mass ratio (r = -0.34, p = 0.008), a highly sensitive marker of malnutrition. We observed an inverse correlation between serum magnesium and hs-CRP (r = -0.37, p = 0.02) in PD patients. In conclusion, lower serum magnesium is associated with poorer nutrition status, deteriorating cellular health, and increased inflammation, which may contribute to the increased risk of mortality in PD patients.

Enrollment fluid status is independently associated with long-term survival of peritoneal dialysis patients.

Fluid overload is a common complication in peritoneal dialysis (PD) patients. The prognostic importance of enrollment fluid status in long-term PD patients remains to be investigated. The objective of the present study was to investigate the prognostic importance of enrollment fluid status in the long-term survival of PD patients. We enrolled 53 PD patients (mean age: 53 years) from November 2000 to February 2006. On enrollment, demographic, clinical, and biochemical data were recorded. Bioelectrical impedance analysis (BIA) was used to determine the fluid status of PD patients, including extracellular water (ECW), intracellular water (ICW), and total body water (TBW). Fluid status was corrected for body surface area (BSA): ECW-BSA, ICW-BSA, and TBW-BSA respectively. Patients were followed to January 2008. The ECW-BSA correlated negatively with albumin, a marker of nutrition (r = -0.53, p < 0.0001). The ICW/ECW ratio (r = 0.36, p = 0.018) correlated directly and the ECW/ TBW ratio (r = -0.36, p = 0.019) correlated negatively with creatinine. Patients who survived during the study period had a significantly lower ECW-BSA (8.29 L/m2 vs. 9.91 L/m2, p = 0.001) than did those who did not survive. Patients with enrollment ECW-BSA below 9 L/m2 had a significantly better 7-year cumulative survival (Kaplan-Meier) than did patients with a ECW-BSA of 9 L/m2 or more (p = 0.019). Using multivariate Cox regression analysis, adjusting for age, race, diabetes, human immunodeficiency virus (HIV) status, and months on dialysis at enrollment, ECW-BSA was a significant independent predictor of mortality (relative risk: 1.50; p = 0.03). In conclusion, ECW-BSA was a significant independent predictor of long-term survival in PD patients.

Relationship of peritoneal transport rate and dialysis adequacy with inflammation in peritoneal dialysis patients.

Inflammation, dialysis adequacy, and peritoneal transport rate (PTR) influence clinical outcomes in peritoneal dialysis (PD) patients. The present study examined the relationship of C-reactive protein (CRP), a marker of inflammation, to PTR and residual renal function (RRF) in PD patients. We recorded the baseline dialysate-to-plasma creatinine (D/P Cr) of 210 PD patients starting in 1986. In a subgroup of 42 patients, we serially measured high-sensitivity CRP levels and.dialysis adequacy, including weekly Kt/V urea and creatinine clearance (CCr), starting in May 2003. The patients were followed to January 2006. Mean age was 53 +/- 16 (standard deviation) years, and 70% of the patients were African American. Enrollment mean and median CRP levels were 13.53 +/- 20.8 (range: 0.2-95.8) and 7.15 mg/L respectively. Mean weekly residual CCr and Kt/V during follow-up were 7.11 +/- 15.47 L/1.73 m2 and 0.14 +/- 0.30 respectively. The mean enrollment D/P Cr was 0.649 +/- 0.12 (range: 0.429-0.954). Patients with CRP > 10 mg/L had significantly lower weekly residual CCr (0.59 L/1.73 m2 vs. 10.1 L/1.73 m2, p = 0.01), residual Kt/V (0.01 vs. 0.20, p = 0.01), total CCr (56 L/1.73 m2 vs. 62 L/1.73 m2, p= 0.047), and total Kt/V (2.09 vs. 2.49, p = 0.001) than did those with CRP < or = 10 mg/L. Levels of CRP correlated negatively with weekly residual CCr (r = -0.42, p = 0.006), residual Kt/V (r = -0.43, p = 0.006), and total Kt/V (r = -0.44, p = 0.004). Enrollment D/P Cr was inversely correlated with serum albumin (r = -0.24, p = 0.001) and directly correlated with peritoneal protein loss (r = 0.34, p = 0.028). Higher enrollment D/P Cr was associated with lower observed cumulative survival (Kaplan-Meier) in PD patients. However D/P Cr was not an independent predictor of long-term survival in PD patients. Using multivariate Cox regression analysis, and including D/P Cr and residual Kt/V in the model, enrollment CRP was an independent predictor of mortality (relative risk = 1.036, p = 0.018). We conclude that elevated CRP is associated with lower RRF As a predictor of mortality, CRP may be better than RRF and D/P Cr.

Usefulness of bioelectrical impedance analysis in monitoring nutrition status and survival of peritoneal dialysis patients.

Malnutrition is highly prevalent in peritoneal dialysis (PD) patients and is associated with higher mortality. Lower serum levels of markers of nutrition--such as albumin, creatinine, prealbumin, and total cholesterol--are important risk factors in PD patients. Usefulness of bioimpedance analysis (BIA) in hemodialysis (HD) patients has been reported. In the present study, we prospectively examined the relationship of bioimpedance indexes to the nutrition status and survival of 45 PD patients who were followed for more than 1 year. On patient enrollment, a BIA was performed (Bioelectrical Impedance Analyzer, Model BIA-101: RJL Systems, Clinton Township, MI, U.S.A.). Monthly blood was analyzed for biochemical markers. The mean age of the study group was 50 +/- 15 years. Of the 45 patients, 56% were female and 24% were diabetic. Mean body mass index was 25.7 +/- 5.1. Mean resistance, reactance, capacitance, and phase angle were 524 +/- 106 omega 57 +/- 20 omega, 678 +/- 223 pF, and 6.2 +/- 1.7 degrees respectively. Patients with diabetes had lower capacitance (555 pF vs. 713 pF, p = 0.007) and phase angle (5.35 degrees vs. 6.4 degrees, p = 0.05) than patients without diabetes. During the study period, 4 patients died. Patients who survived had higher capacitance (486 +/- 163 pF vs. 697 +/- 218 pF, p = 0.07) and phase angle (4.65 +/- 0.73 degrees, vs. 6.34 +/- 1.67 degrees, p = 0.008) than those who did not survive. The Kaplan-Meier method was used to compute observed survival. The cumulative observed survival of PD patients with an enrollment phase angle > or = 6 degrees was significantly (p = 0.01) higher than that of patients with an enrollment phase angle < 6 degrees. Reactance was directly correlated with albumin (r = 0.52, p < 0.0001) and total protein (r = 0.44, p < 0.05). Capacitance was directly correlated with body mass index (r = 0.35, p < 0.05), albumin (r = 0.32, p < 0.05), and blood urea nitrogen (BUN) (r = 0.44, p < 0.01), and inversely correlated with body weight (r = -0.51, p < 0.0001). Phase angle was directly correlated with all of the biochemical markers of nutrition, such as albumin (r = 0.54, p < 0.01), total protein (r = 0.38, p < 0.05), creatinine (r = 0.28, p < 0.01), and BUN (r = 0.39, p < 0.05). By stepwise multivariate regression analysis, body weight (beta = -0.60, p < 0.0001) and total protein (beta = 0.32, p = 0.012) were significant determinants of resistance. Body weight (beta = -0.31, p = 0.02) and albumin (beta = 0.59, p < 0.0001) were significant predictors of reactance. Serum albumin (beta = 0.53, p < 0.0001) was the only best predictor of phase angle in PD patients. The BIA indices reflect nutrition status in PD patients, and may be useful in monitoring nutrition interventions.