Serum albumin, body weight and inflammatory parameters in chronic hemodialysis patients: a three-year longitudinal study

Clinical predictors of decline in nutritional parameters over time in ESRD

BACKGROUND AND OBJECTIVES

Inflammation and malnutrition are important features in patients with ESRD; however, data on changes in these parameters over time are scarce. This study aimed to gain insight into changes over time in serum albumin, body mass index, high-sensitivity C-reactive protein, and IL-6 in patients with ESRD and aimed to identify clinical risk factors for deterioration of these parameters.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data were analyzed from the Convective Transport Study, a randomized controlled trial conducted from June 2004 to January 2011, in which 714 patients with chronic ESRD were randomized to either online hemodiafiltration or low-flux hemodialysis. Albumin and body mass index were measured up to 6 years and predialysis C-reactive protein and IL-6 were measured up to 3 years in a subset of 405 participants. Rates of change in these parameters over time were estimated across strata of predefined risk factors with linear mixed-effects models.

RESULTS

Albumin and body mass index decreased and C-reactive protein and IL-6 increased over time. For every incremental year of age at baseline, the yearly excess decline in albumin was 0.003 g/dl (-0.004 to -0.002; P<0.001) and the excess decline in body mass index was 0.02 kg/m(2) per year (-0.02 to -0.01; P<0.001). In patients with diabetes mellitus, there was a yearly excess decline of 0.05 g/dl in albumin (-0.09 to -0.02; P=0.002). Compared with women, men had an excess decline of 0.03 g/dl per year in albumin (-0.06 to -0.001; P=0.05) and an excess increase of 11.6% per year in IL-6 (0.63%-23.6%; P=0.04).

CONCLUSIONS

Despite guideline-based care, all inflammatory and nutritional parameters worsened over time. The deterioration of some of these parameters was more pronounced in men, older patients, and patients with diabetes mellitus. Special focus on the nutritional status of at-risk patients by individualizing medical care might improve their prognosis.

Serum albumin as predictor of nutritional status in patients with ESRD

BACKGROUND AND OBJECTIVES

Serum albumin is a widely used biomarker of nutritional status in patients with CKD; however, its usefulness is debated. This study investigated serum albumin and its correlation with several markers of nutritional status in incident and prevalent dialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a cross sectional study, serum albumin (bromocresol purple), and other biochemical (serum creatinine), clinical (subjective global assessment [SGA]), anthropometric (handgrip strength, skinfold thicknesses), and densitometric (dual energy x-ray absorptiometry) markers of nutritional status were assessed in 458 incident (61% male; mean age 54 +/- 13 years; GFR, 6.6 +/-2.3 ml/min per 1.73 m(2); recruited 1994–2010) and 383 prevalent (56% male; mean age 62 +/- 14 years; recruited 1989–2004) dialysis patients.

RESULTS

In incident patients: serum albumin was correlated with sex (beta = -0.13; P = 0.02), diabetes mellitus (beta = -0.18; P = 0.004), and urinary albumin excretion (beta = -0.42; P = 0.001) but less so with poor nutritional status (SGA score >1; beta = -0.19; P = 0.001). In prevalent patients, serum albumin was correlated with age (beta = -0.14; P = 0.05), high-sensitivity C-reactive protein (beta = -0.34; P = 0.001), diabetes mellitus (beta = -0.11; P = 0.04), and SGA score >1 (beta = -0.14; P = 0.003). In predicting nutritional status assessed by SGA and other markers, adding serum albumin to models that included age, sex, diabetes, and cardiovascular disease did not significantly increase explanatory power.

CONCLUSIONS

In incident and prevalent dialysis patients,serum albumin correlates poorly with several markers of nutritional status. Thus, its value as a reliable marker of nutritional status in patients with ESRD is limited. In addition, the following inconsistencies between the main text and Tables 1 and 3 are also corrected as follows. (1) In Table 1, the GFR initially written as 6 +/- 3 ml/min per 1.73(2) should be corrected to 6.6 +/- 2.3 ml/min per 1.73(2). (2) On line 11 of page 1448, under the Clinical Correlates of Serum Albumin Concentration section describing the multiple regression models (Table 3), the P value was initially written as“serum albumin was associated with age (beta = -0.14; P = 0.05).” The P value should be corrected to have the same value as that given in Table 3 (beta = -0.14; P = 0.005. [corrected].

IL-6 levels, nutritional status, and mortality in prevalent hemodialysis patients

BACKGROUND AND OBJECTIVES

The influence of serum IL-6 levels on nutritional status in chronic hemodialysis (HD) patients remains to be elucidated. The present report describes a prospective longitudinal study of IL-6 levels and nutritional parameters to determine whether high IL-6 levels are independently associated with nutritional status over time in a cohort of prevalent hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

85 clinically stable hemodialysis patients (37.6% women), with a mean age of 66.5 ± 10.6 years, were studied after exclusion of patients with BMI < 20 kg/m(2) and/or serum albumin <35 g/L. IL-6, dietary energy and protein intake, and biochemical markers of nutrition and body composition (anthropometry and bioimpedance analysis) were measured at baseline and at 6, 12, 18, and 24 months following enrollment. Observation of this cohort was continued over 2 additional years.

RESULTS

IL-6 levels increased with time in both unadjusted (linear estimate: 2.57 ± 0.44 pg/ml per 2 yrs; P = 0.001) and adjusted models (linear estimate: 2.35 ± 0.57 pg/ml per 2 yrs; P = 0.049). Significant reductions of daily energy intake, laboratory markers (albumin, transferrin, cholesterol, creatinine), and body composition (fat mass) with higher IL-6 levels were observed over the duration of the longitudinal observation period. However, none of the studied parameters were associated with changes in IL-6 levels over time (IL-6-by-time interactions were NS). Furthermore, cumulative incidences of survival were correlated with the baseline serum IL-6 levels (P = 0.004 by log-rank test). Finally, for each pg/ml increase in IL-6 level, the hazard ratio for death from all causes was 1.06 (95% CI 1.01 to 1.10) after adjustment for demographic and clinical parameters.

CONCLUSIONS

Our results suggest that higher serum IL-6 levels are associated with all-cause mortality without additional changes in clinical and laboratory markers of nutritional status in clinically stable HD patients.

Longitudinal study of leptin levels in chronic hemodialysis patients

Background

The influence of serum leptin levels on nutritional status and survival in chronic hemodialysis patients remained to be elucidated. We conducted a prospective longitudinal study of leptin levels and nutritional parameters to determine whether changes of serum leptin levels modify nutritional status and survival in a cohort of prevalent hemodialysis patients.

Methods

Leptin, dietary energy and protein intake, biochemical markers of nutrition and body composition (anthropometry and bioimpedance analysis) were measured at baseline and at 6, 12, 18 and 24 months following enrollment, in 101 prevalent hemodialysis patients (37% women) with a mean age of 64.6 ± 11.5 years. Observation of this cohort was continued over 2 additional years. Changes in repeated measures were evaluated, with adjustment for baseline differences in demographic and clinical parameters.

Results

Significant reduction of leptin levels with time were observed (linear estimate: -2.5010 ± 0.57 ng/ml/2y; p < 0.001) with a more rapid decline in leptin levels in the highest leptin tertile in both unadjusted (p = 0.007) and fully adjusted (p = 0.047) models. A significant reduction in body composition parameters over time was observed, but was not influenced by leptin (leptin-by-time interactions were not significant). No significant associations were noted between leptin levels and changes in dietary protein or energy intake, or laboratory nutritional markers. Finally, cumulative incidences of survival were unaffected by the baseline serum leptin levels.

Conclusions

Thus leptin levels reflect fat mass depots, rather than independently contributing to uremic anorexia or modifying nutritional status and/or survival in chronic hemodialysis patients. The importance of such information is high if leptin is contemplated as a potential therapeutic target in hemodialysis patients.