Survival advantages of obesity in dialysis patients

Obesity, diabetes, and chronic kidney disease

Similar to diabetes, obesity is associated with the early onset of glomerulomegaly, hemodynamic changes of a hyperfiltering kidney, and increased albuminuria, which are potentially reversible with weight loss. However, the pathologic lesions of focal segmental glomerulosclerosis in experimental models of sustained obesity, and in obese humans presenting with massive proteinuria, are different from those of classic diabetic nephropathy. In addition, several observational, cross-sectional, and longitudinal studies document obesity as an independent risk factor for the onset, aggravated course, and poor outcomes of chronic kidney disease, even after adjustment for confounding comorbidities, including diabetes and hypertension, the two major causes of chronic kidney disease.

Is the declining use of long-term peritoneal dialysis justified by outcome data?

In the past decade, peritoneal dialysis use among patients with end-stage renal disease has declined in many countries. Studies from the United States indicate that many academic centers do not have adequate resources to train fellows, most incident dialysis patients are not offered peritoneal dialysis, and more than half of dialysis clinics do not have the infrastructure to support peritoneal dialysis. Some are concerned that the outcomes of peritoneal dialysis and maintenance hemodialysis patients may not be equivalent, a notion that is not supported by outcome studies. Given the effect of modality selection on patients' lifestyle, attempts to conduct a randomized, controlled comparison of maintenance hemodialysis and peritoneal dialysis have been unsuccessful. Most observational studies showed that peritoneal dialysis is associated with a survival advantage that diminishes over time; it is unclear whether any of the differences over time are attributable to the modality. Between 1996 and 2003, the early outcomes of peritoneal dialysis patients further improved, whereas those for maintenance hemodialysis patients remained unchanged. Differences in outcomes may be due to residual statistical confounding; however, several biologic mechanisms can be postulated: The early survival advantage may be related to the better preservation of residual renal function with peritoneal dialysis, and the diminution of the survival advantage may be related to worsened volume control. There is a need for large observational and interventional studies among peritoneal dialysis patients to sustain and enforce the improvements in both dialysis therapies.

Racial and survival paradoxes in chronic kidney disease

Most of the 20 million people in the US with chronic kidney disease (CKD) die before commencing dialysis. One of every five dialysis patients dies each year in the US. Although cardiovascular disease is the most common cause of death among patients with CKD, conventional cardiovascular risk factors such as hypercholesterolemia, hypertension and obesity are paradoxically associated with better survival in hemodialysis populations. Emerging data indicate the existence of this 'reverse epidemiology' in earlier stages of CKD. There are also paradoxical relationships between outcomes and race and ethnicity. For example, the survival rate of African American dialysis patients seems to be superior to that of whites on dialysis. Paradoxes-within-paradoxes have been detected among Hispanic and Asian American CKD patients. These survival paradoxes might evolve and change over the natural course of CKD progression as a result of the time differentials of competing risk factors and the overwhelming impact of malnutrition, inflammation and wasting. Reversal of the reverse epidemiology as a result of successful kidney transplantation underscores the role of nutritional status and kidney function in engendering these paradoxes. The observation of paradoxes and their reversal might lead to the formulation of new paradigms and management strategies to improve the survival of patients with CKD. Such movement away from the use of targets set on the basis of data gathered in general populations (e.g. the Framingham cohort) would be a major paradigm shift in clinical medicine and public health.

The obesity paradox and myocardial infarct size

OBJECTIVE

Obese subjects have a risk of death from cardiovascular disease higher than those with normal body weight. Obese patients, however, have a better outcome when undergoing coronary revascularisation, and when suffering from heart failure or chronic kidney disease. The term 'obesity paradox' underlines the divergence between increased risk and better outcome in sick obese patients. We tested the hypothesis that the obesity paradox could also occur in myocardial infarction.

METHODS

A group of 89 patients (mean age 62 +/- 11 years) with previous myocardial infarction (Q-wave in 72 patients) underwent contrast-enhanced MRI.

RESULTS

Areas of delayed contrast enhancement (which reflects myocardial necrosis) were present in 15 +/- 9% of left ventricular myocardium. Infarct size was not influenced by patient age, gender, history of arterial hypertension, hypercholesterolaemia, hypertriglyceridaemia nor tobacco smoking. Infarct size, however, was larger in insulin-dependent diabetic patients (P = 0.06) and in those with a family history of premature coronary artery disease (P = 0.06). Surprisingly, infarct size was smaller in obese patients (11 +/- 4% of left ventricular myocardium) than in those with normal body weight (16 +/- 9% of left ventricular myocardium, P = 0.03). Insulin-dependent diabetes mellitus, obesity and family history of coronary artery disease were the only independent predictors of infarct size at multiple linear regression analysis.

CONCLUSIONS

Owing to its limitations (small sample size and exclusion of extremely obese patients), this study generates a working hypothesis, which should be tested in larger prospective studies, that the obesity paradox could also occur in myocardial infarction.

Noninvasive Measurement of Cardiac Output in Hemodialysis Patients by Task Force Monitor: A Comparison with the Transonic System

Cardiovascular disease is the leading cause of morbidity and mortality in maintenance hemodialysis (MHD) patients. The Transonic (TRS; Transonic Systems, Ithaca, NY) device is frequently used for determination of cardiac output (CO) by an indicator dilution technique. The Task Force Monitor (TFM; CN Systems, Graz, Austria) has gained attention as noninvasive tool for continuous beat-to-beat assessment of cardiovascular variables, including CO by impedance cardiography. Despite its use in cardiology and intensive care settings, the TFM has yet not been validated in dialysis patients. This study compares CO measurements in 12 MHD patients by TFM and TRS. Bland-Altman and regression analysis were used. CO was measured simultaneously by TRS and TFM. Average CO was 5.4 L/min by TRS and 5.0 L/min by TFM, respectively. Bland-Altman analysis revealed no significant systematic differences between the two methods (mean difference: 0.4 L/min; SD: 0.6; p > 0.05). Linear regression analysis showed significant correlation between both techniques (r = 0.802, p = 0.002). The SD of mean individual CO values was 1.1 L/min with TRS and 0.8 L/min with TFM, respectively.CO measured by TFM and TRS does not differ significantly, thus making the TFM an attractive noninvasive tool for the continuous beat-to-beat assessment of CO in MHD patients.

Body Mass Index and Mortality in CKD

BACKGROUND

Greater body mass index (BMI) is associated with worse survival in the general population, but appears to confer a survival advantage in patients with kidney failure treated by hemodialysis. Data are limited on the relationship of BMI with mortality in patients in the earlier stages of chronic kidney disease (CKD).

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

The Modification of Diet in Renal Disease (MDRD) Study examined the effects of dietary protein restriction and blood pressure control on progression of kidney disease. This analysis includes 1,759 subjects.

PREDICTOR

BMI.

OUTCOMES & MEASUREMENTS

Cox models were used to evaluate the relationship of quartiles of BMI with all-cause and cardiovascular disease (CVD) mortality.

RESULTS

Mean GFR and BMI were 39 +/- 21 (SD) mL/min/1.73 m(2) and 27.1 +/- 4.7 kg/m(2), respectively. During a mean follow-up of 10 years, there were 453 deaths (26%), including 272 deaths (16%) from CVD. In unadjusted Cox models, quartiles 3 (hazard ratio [HR], 1.45; 95% confidence interval [CI], 1.11 to 1.90) and 4 (HR, 1.58; 95% CI, 1.21 to 2.06) were associated with increased risk of all-cause mortality compared with quartile 1. Adjustment for demographic, CVD, and kidney disease risk factors and randomization status attenuated this relationship for quartiles 3 (HR, 0.81; 95% CI, 0.60 to 1.09) and 4 (HR, 0.83; 95% CI, 0.61 to 1.20). In unadjusted Cox models, quartiles 3 (HR, 1.66; 95% CI, 1.17 to 2.36) and 4 (HR, 1.63; 95% CI, 1.15 to 2.33) were associated with increased risk of CVD mortality. Multivariable adjustment attenuated this relationship for quartiles 3 (HR, 0.92; 95% CI, 0.63 to 1.36) and 4 (HR, 0.85; 95% CI, 0.57 to 1.27).

LIMITATIONS

Primary analyses were based on single measurement of BMI. Because the MDRD Study cohort included relatively young white subjects with predominantly nondiabetic CKD, results may not be generalizable to all patients with CKD.

CONCLUSIONS

In this cohort of subjects with predominantly nondiabetic CKD, BMI does not appear to be an independent predictor of all-cause or CVD mortality.

High Body Mass Index and Posttransplant Weight Gain Are Not Risk Factors for Kidney Graft and Patient Outcome

BACKGROUND

High body mass constitutes a significant risk factor for morbidity and mortality in the general population, but it has been associated with an increased survival among dialysis patients. Its effects on renal transplant outcomes are controversial. The aim of our present work was to investigate the impact of high body mass and posttransplant weight gain on patient and graft outcomes.

PATIENTS AND METHODS

One thousand consecutive renal transplant recipients (631 men and 369 women) were included in the study. Their mean age was 42.9 years and the follow-up was at least 2 years. Basal immunosuppression was azathioprine (Aza) and steroids in 196 patients, cyclosporine (CsA) without or with antiproliferative agent in 557, and 239 were presented tacrolimus (Tac).

RESULTS

At the time of transplantation the body mass index (BMI) was 23.7 +/- 3.9 kg/m2, namely, <18.5 kg/m2 in 6.3%; 18.5 to 25 in 61.7%; 25 to 30 in 25.4%; and >30 in 6.5%. Pretransplant obesity was associated with old age and female gender. Obese patients experienced a greater risk of delayed graft function (P < .01) and surgical wound complications (P < .01). After 1 year, 299 patients (29.9%) displayed weight gain >10% (mean 8.6% +/- 10.4% or 5.0 +/- 6.1 kg). Patients on Aza showed increased body weight by 11.9% +/- 10.9%; CsA patients by 9.5% +/- 10.3%, and Tac patients by 4.9% +/- 9.1% (P < .001). Univariate and multivariate analysis showed that pretransplant BMI had no effect on graft or patient survival either in the whole group or in the patients treated with CsA or TAC. Posttransplant weight gain above 5% or 10% did not influence graft or patient outcomes.

CONCLUSIONS

The new immunosuppressive regimes reduce posttransplant weight gain. Pretransplant high body mass and 1-year posttransplant weight gain were not risk factors for graft or patient survival in our experience.

HDL-inflammatory index correlates with poor outcome in hemodialysis patients

Oxidative stress and cardiovascular disease are risk factor of patients with chronic kidney disease (CKD) on maintenance hemodialysis. We used the fluorescence of low-density lipoprotein as an index of its proinflammatory potential to examine any role that high-density lipoprotein (HDL) might have in promoting this effect. The total body fat of the patients was measured by means of near-infrared interactance and their quality of life by means of SF36 questionnaires. In 189 randomly selected patients, followed for 30 months, HDL was found to be significantly anti-inflammatory but with a large standard deviation. Fully 17% of the patients had a decidedly proinflammatory index along with inferior SF36 scores. The patients were divided into 10% increments of total body fat percentages up to 40%. HDL was found to be progressively proinflammatory the higher the body fat content. Patients with a higher HDL proinflammatory index had a higher 30-month adjusted hazard ratio for death than those whose HDL were seen to be anti-inflammatory. Our findings suggest an important role of inflammatory HDL in patients with CKD leading to poor outcome.

Associations of body size with metabolic syndrome and mortality in moderate chronic kidney disease

BACKGROUND AND OBJECTIVES

Obesity is associated with metabolic syndrome and poor outcomes in those with normal kidney function but better survival in dialysis patients. We examined whether chronic kidney disease (CKD) modifies the association of obesity with metabolic syndrome and mortality.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Analyses of 15,355 participants in limited access, public use Atherosclerosis Risk in Communities Study database.

RESULTS

The prevalence of metabolic syndrome in (BMI) groups < 20, 20 to 24.9, 25 to 29.9, 30 to 34.9, and > or = 35 kg/m2 were 1, 6, 17, 28, and 35% and 9, 15, 32, 46, and 58% in participants without (n = 14,894) and with CKD (n = 461), respectively. Using BMI 20 to 24.9 kg/m2 as the reference, there was a U-shaped association of BMI with mortality in a parametric survival model of death. An interaction term of BMI and CKD added to the model was significant. In participants with (BMI) > or = 25 kg/m2, each 1-kg/m2 increase in BMI was associated with increased hazard of death only in those without CKD. Adjustment for components of metabolic syndrome, markers of inflammation, and cardiovascular conditions abolished these associations in participants without CKD but became protective in participants with CKD.

CONCLUSIONS

The prevalence of obesity parallels metabolic syndrome in populations with and without CKD. However, the presence of CKD modifies the associations of obesity with mortality.

Risk factor paradox in wasting diseases

PURPOSE OF REVIEW

Emerging data indicate that conventional cardiovascular risk factors (e.g. hypercholesterolemia and obesity) are paradoxically associated with better survival in distinct populations with wasting. We identify these populations and review survival paradoxes and common pathophysiologic mechanisms.

RECENT FINDINGS

A 'reverse epidemiology' of cardiovascular risk is observed in chronic kidney disease, chronic heart failure, chronic obstructive lung disease, cancer, AIDS and rheumatoid arthritis, and in the elderly. These populations apparently have slowly progressive to full-blown wasting and significantly greater short-term mortality than the general population. The survival paradoxes may result from the time differential between the two competing risk factors [i.e. over-nutrition (long-term killer but short-term protective) versus undernutrition (short-term killer)]. Hemodynamic stability of obesity, protective adipokine profile, endotoxin-lipoprotein interaction, toxin sequestration of fat, antioxidation of muscle, reverse causation, and survival selection may also contribute.

SUMMARY

The seemingly counterintuitive risk factor paradox is the hallmark of chronic disease states or conditions associated with wasting disease at the population level. Studying similarities among these populations may help reveal common pathophysiologic mechanisms of wasting disease, leading to a major shift in clinical medicine and public health beyond the conventional Framingham paradigm and to novel therapeutic approaches related to wasting and short-term mortality.

Relation of body mass index to outcome in patients with known or suspected coronary artery disease

Increased body mass index (BMI), a parameter of total body fat content, is associated with an increased mortality in the general population. However, recent studies have shown a paradoxic relation between BMI and mortality in specific patient populations. This study investigated the association of BMI with long-term mortality in patients with known or suspected coronary artery disease. In a retrospective cohort study of 5,950 patients (mean age 61 +/- 13 years; 67% men), BMI, cardiovascular risk markers (age, gender, hypertension, diabetes, current smoking, angina pectoris, old myocardial infarction, heart failure, hypercholesterolemia, and previous coronary revascularization), and outcome were noted. The patient population was categorized as underweight, normal, overweight, and obese based on BMI according to the World Health Organization classification. Mean follow-up time was 6 +/- 2.6 years. Incidences of long-term mortality in underweight, normal, overweight, and obese were 39%, 35%, 24%, and 20%, respectively. In a multivariate analysis model, the hazard ratio (HR) for mortality in underweight patients was 2.4 (95% confidence interval [CI] 1.7 to 3.7). Overweight and obese patients had a significantly lower mortality than patients with a normal BMI (HR 0.65, 95% CI 0.6 to 0.7, for overweight; HR 0.61, 95% CI 0.5 to 0.7, for obese patients). In conclusion, BMI is inversely related to long-term mortality in patients with known or suspected coronary artery disease. A lower BMI was an independent predictor of long-term mortality, whereas an improved outcome was observed in overweight and obese patients.

Body composition and physical activity in end-stage renal disease

OBJECTIVE

The study objective was to examine the relationship between visceral and somatic protein stores and physical activity in individuals with end-stage renal disease.

DESIGN

This was a prospective single-center study.

SETTING

The study took place at the Vanderbilt University Outpatient Dialysis Unit and General Clinical Research Center.

PATIENTS

Fifty-five patients with prevalent chronic hemodialysis (CHD) were included: 33 males, 22 females, 45 African Americans, 9 Caucasians, and 1 Asian. The mean age was 47.0 +/- 1.6 years, height was 166.4 +/- 13.9 cm, and weight was 83.1 +/- 2.6 kg.

METHODS

Body composition was measured by dual-energy x-ray absorptiometry. Minute-by-minute physical activity was assessed over a 7-day period with a triaxial accelerometer. Participants were interviewed by a trained registered dietitian for two 24-hour diet recalls (one from a hemodialysis day; one from a nonhemodialysis day). Laboratory values for serum concentrations of albumin, prealbumin, C-reactive protein, and creatinine were also collected.

MAIN OUTCOME MEASURE

Predictors of somatic protein stores were the main outcome measure.

RESULTS

Serum albumin was negatively and significantly correlated with the percentage of fat mass (P = .016) and kg of fat mass (P = .044). C-reactive protein was positively and significantly correlated with body weight (P = .006), percentage of fat mass (P = .017), kg of fat mass (P = .006), and body mass index (P = .004). Physical activity and total daily protein intake were the strongest predictors of the amount of lean body mass (P = .01 and .003, respectively).

CONCLUSION

The association between somatic protein and visceral protein stores is weak in patients with CHD. Whereas increased levels of physical activity and total daily protein intake are associated with higher lean body mass in patients with CHD, higher adiposity is associated with higher C-reactive protein and lower albumin values.

A1C and survival in maintenance hemodialysis patients

OBJECTIVE

The optimal target for glycemic control has not been established in diabetic dialysis patients.

RESEARCH DESIGN AND METHODS

To address this question, the national database of a large dialysis organization (DaVita) was analyzed via time-dependent survival models with repeated measures.

RESULTS

Of 82,933 patients undergoing maintenance hemodialysis (MHD) in DaVita outpatient clinics over 3 years (July 2001 through June 2004), 23,618 diabetic MHD patients had A1C measurements at least once. Unadjusted survival analyses indicated paradoxically lower death hazard ratios (HRs) with higher A1C values. However, after adjusting for potential confounders (demographics, dialysis vintage, dose, comorbidity, anemia, and surrogates of malnutrition and inflammation), higher A1C values were incrementally associated with higher death risks. Compared with A1C in the 5-6% range, the adjusted all-cause and cardiovascular death HRs for A1C > or = 10% were 1.41 (95% CI 1.25-1.60) and 1.73 (1.44-2.08), respectively (P < 0.001). The incremental increase in death risk for rising A1C values was monotonic and robust in nonanemic patients (hemoglobin > 11.0 g/dl). In subgroup analyses, the association between A1C > 6% and increased death risk was more prominent among younger patients, those who had undergone dialysis for > 2 years, and those with higher protein intake (> 1 g x kg(-1) x day(-1)), blood hemoglobin (> 11 g/dl), or serum ferritin values (> 500 ng/ml).

CONCLUSIONS

In diabetic MHD patients, the apparently counterintuitive association between poor glycemic control and greater survival is explained by such confounders as malnutrition and anemia. All things equal, higher A1C is associated with increased death risk. Lower A1C levels not related to malnutrition or anemia appear to be associated with improved survival in MHD patients.

Circulating levels of visfatin/pre-B-cell colony-enhancing factor 1 in relation to genotype, GFR, body composition, and survival in patients with CKD

BACKGROUND

Visfatin, also known as pre-B-cell colony-enhancing factor 1 (PBEF-1), recently was shown to be secreted from adipocytes and have insulin-mimetic properties in mice. Because renal failure per se is associated with both increased levels of circulating peptides and marked insulin resistance, even in the absence of diabetes mellitus, we hypothesized that visfatin could be a factor linking inflammation, kidney disease, and insulin resistance in this patient group.

METHODS

Altogether, we studied 189 patients with chronic kidney disease (CKD), comprising 149 patients with CKD stage 5 (glomerular filtration rate [GFR] < 15 mL/min; mean, 7 +/- 2 mL/min [<0.25 mL/s; mean, 0.12 +/- 0.03 mL/s]; 61% men; mean age, 54 +/- 12 years) and 40 patients with CKD stages 3 to 4 (GFR, 15 to 60 mL/min; mean, 33 +/- 21 mL/min [0.25 to 1.00 mL/s; mean, 0.55 +/- 0.35 mL/s]; 72% men; age, 59 +/- 15 years). We compared these with 30 randomly selected population controls (mean GFR, 85 +/- 16 mL/min [1.42 +/- 0.27 mL/s]; 69% men; age, 64 +/- 11 years). Serum visfatin was measured by using commercially available enzyme-linked immunosorbent assay, and we also performed genotyping of 3 verified polymorphisms in the visfatin gene (-423A/G, -1001T/G, and -1535C/T). Body fat was estimated by using dual-energy x-ray absorptiometry.

RESULTS

Serum visfatin levels were greater in patients with CKD stage 5 (41.3 +/- 18.0 ng/mL) than in those with CKD stages 3 to 4 (34.0 +/- 9.8 ng/mL; P < 0.01 versus CKD stage 5) or healthy controls (29.3 +/- 8.1 ng/mL; P < 0.0001). However, there were no significant differences between patients with and without diabetes, and the significant differences in circulating visfatin levels between genotypes disappeared after adjustment for differences in age, sex, GFR, and serum albumin level. In univariate analysis, visfatin level correlated with levels of GFR (rho = -0.22; P = 0.001), interleukin 6 (IL-6; rho = 0.17; P = 0.01), high-sensitivity C-reactive protein (rho = 0.14; rho < 0.05), and soluble vascular cell adhesion molecule 1 (sVCAM-1; rho = 0.39; P < 0.0001), but not total or truncal fat mass, insulin resistance, or hemoglobin A(1c) level. High plasma visfatin level predicted mortality in patients with CKD, also after adjustment for age and sex (likelihood ratio, 18.2; P < 0.0001), but not after additional correction for GFR, sVCAM-1, serum albumin, and serum IL-6 levels.

CONCLUSION

Circulating levels of the cytokine visfatin/PBEF-1 are influenced by renal function, but are not associated with fat mass or surrogate markers of insulin resistance in patients with CKD. Visfatin was associated independently with level of sVCAM-1, a marker of endothelial damage.

Impact of kidney bone disease and its management on survival of patients on dialysis

Despite the enormous cardiovascular disease epidemic and poor survival among individuals with chronic kidney disease (CKD), traditional risk factors such as hypercholesterolemia, hypertension, and obesity appear not as relevant as was previously thought, nor would their management improve survival in patients with CKD who are undergoing dialysis. On the contrary, kidney disease wasting (KDW) (also known as the malnutrition-inflammation complex), renal anemia, and kidney bone disease (KBD) appear to be the 3 most important nontraditional risk factors associated with cardiovascular disease in CKD. KBD-associated hyperparathyroidism may contribute to worsening refractory anemia and KDW/inflammation. The main cause of secondary hyperparathyroidism is active vitamin D deficiency. Hence, treatment of patients with KBD with vitamin D analogs, especially those with lesser effects on calcium and phosphorus such as paricalcitol, may be the most promising option for improving CKD outcomes. By conducting survival analyses in a 2-year (7/2001 to 6/2003) cohort of 58,058 patients on hemodialysis, we recently found that associations between high serum parathyroid hormone and increased death risk were masked by the demographic and clinical characteristics of patients, and that alkaline phosphatase had an incremental association with mortality. Administration of paricalcitol was associated with improved survival in time-varying models. We now present additional subgroup analyses that show that administration of any dose of paricalcitol, when compared with no paricalcitol, is associated with better likelihood of survival in virtually all subgroups of patients on hemodialysis. Because these associations may be secondary to bias by indication, randomized clinical trials are necessary to verify the findings of this and similar observational studies.

Lack of Synergistic Effects of Metabolic Syndrome and Plasma Fibrinogen on Coronary Events and Mortality in Moderate CKD

BACKGROUND

Metabolic syndrome and inflammation are interlinked in patients with moderate chronic kidney disease (CKD).

METHODS

We examined whether these 2 conditions exert additive or multiplicative joint effects on subsequent coronary events and death in 710 Atherosclerosis Risk in Communities Study participants with a glomerular filtration rate less than 60 mL/min/1.73 m(2) (<1.0 mL/s).

RESULTS

From the lowest to the highest quartile of level of plasma fibrinogen (an inflammation marker), the prevalence of metabolic syndrome (39%, 46%, 47%, and 64%; P < 0.001) increased. In multivariate Cox regression models, each 100-mg/dL increase in plasma fibrinogen level was associated with a significantly increased hazard of fatal/nonfatal coronary events (hazard ratio [HR], 1.62; 95% confidence interval [CI], 1.33 to 1.98) and death (HR, 1.49; 95% CI, 1.28 to 1.74). In the same models, metabolic syndrome also was associated with coronary events (HR, 1.49; 95% CI, 1.01 to 2.20) and death (HR, 1.40; 95% CI, 1.01 to 1.94). There was no significant interaction of plasma fibrinogen and metabolic syndrome with respect to risk of both fatal/nonfatal coronary events (P = 0.79) and death (P = 0.29). However, patients without metabolic syndrome and in the lowest quartile of plasma fibrinogen levels had the lowest incidence of fatal/nonfatal coronary events or death, whereas those with metabolic syndrome and in the highest quartile of plasma fibrinogen levels had the highest incidence of these events.

CONCLUSION

Inflammation is associated strongly with metabolic syndrome in patients with moderate CKD. Inflammation and metabolic syndrome have additive and not multiplicative joint effects on coronary events and death.

Association between body mass index and mortality is similar in the hemodialysis population and the general population at high age and equal duration of follow-up

The association of body mass index (BMI) with mortality in hemodialysis patients has been found to be reversed in comparison with the general population. This study examined the association of BMI with mortality in the hemodialysis population and the general population when age and time of follow-up were made strictly comparable. Hemodialysis patients who were aged 50 to 75 yr at the start of follow-up were selected from the Netherlands Cooperative Study on the Adequacy of Dialysis-2 (NECOSAD), a prospective cohort study in incident dialysis patients in the Netherlands (n = 722; age 66 +/- 7 yr; BMI 25.3 +/- 4.5 kg/m(2)), and compared with adults who were aged 50 to 75 yr and included in the Hoorn Study, a population-based prospective cohort study in the same country (n = 2436; age 62 +/- 7 yr; BMI 26.5 +/- 3.6 kg/m(2)). In both populations, 2- and 7-yr standardized mortality rates were calculated for categories of BMI. Adjusted hazard ratios (HR) of BMI categories were calculated with a BMI of 22.5 to 25 kg/m(2) as the reference category within each population. In 7 yr of follow-up, standardized mortality rates were approximately 10 times higher in the hemodialysis population than those in the general population. Compared with the reference category, the HR of BMI <18.5 kg/m(2) was 2.0 (95% confidence interval [CI]1.2 to 3.4) in the hemodialysis population and 2.3 (95% CI 0.7 to 7.5) in the general population. Obesity (BMI >or=30 kg/m(2)) was associated with a HR of 1.2 (95% CI 0.8 to 1.7) in the hemodialysis population and 1.3 (95% CI 0.9 to 2.0) in the general population. In conclusion, a hemodialysis population and a general population with comparable age and equal duration of follow-up showed similar mortality risk patterns associated with BMI. This suggests that there is no reverse epidemiology of BMI and mortality in hemodialysis patients. The clinical implication of this study is that to improve survival in the hemodialysis population, more attention should be paid to patients who are underweight instead of overweight.

Changes in fat mass correlate with changes in soluble sCD163, a marker of mature macrophages, in patients with CKD

BACKGROUND

Recently, adipose tissue was shown to contain macrophages capable of contributing to systemic inflammation and cardiovascular disease (CVD). Here, we investigate this putative relationship in patients with chronic kidney disease (CKD) by using the novel macrophage marker soluble (s)CD163.

METHODS

One hundred twenty patients with CKD stage 5 (mean glomerular filtration rate [GFR], 7 +/- 1 mL/min [0.12 +/- 0.02 mL/s; mean age, 53 +/- 1 years; 65% men), 38 patients with CKD stages 3 to 4 (mean GFR, 33 +/- 3 mL/min [0.55 +/- 0.05 mL/s]; mean age, 67 +/- 2 years; 68% men), and 28 healthy controls (mean GFR, 89 +/- 3 mL/min [1.48 +/- 0.05 mL/s]; mean age, 63 +/-2 years; 69% men) were characterized post hoc with a follow-up of up to 5 years (mean, 47 +/- 1 months). sCD163 levels, body composition (dual-energy x-ray absorptiometry), clinical parameters, and levels of circulating inflammatory markers (enzyme-linked immunosorbent assay) were assessed at baseline and, in a subset population, after 1 year of dialysis therapy (hemodialysis, n = 19; peritoneal dialysis, n = 30).

RESULTS

sCD163 level increased in patients with both severe (median, 4.3 mg/L; range, 1.3 to 23.4 mg/L) and moderate (median, 3.6 mg/L; range, 1.6 to 9.8 mg/L) CKD compared with controls (median, 2.6 mg/L; range, 0.8 to 7.6 mg/L; P < 0.001). Furthermore, sCD163 levels correlated with both truncal (rho = 0.17; P < 0.05) and total (rho = 0.17; P < 0.05) fat mass, as well as with all measured markers of inflammation and endothelial adhesion molecules. After 1 year, patients who increased body fat mass (average, 11% +/- 5% versus -5% +/- 5%; P < 0.05) also showed a significant increase in sCD163 levels (median, 2.2 versus -0.97 mg/L; P < 0.01). Finally, patients with sCD163 levels greater than 4.0 mg/L had a statistically significantly worse outcome than patients with sCD163 levels less than this value, even after adjustment for age, sex, and diabetes mellitus (chi-square = 19.98; P < 0.001). However, this effect was lost after adjustment for either inflammation or CVD.

CONCLUSION

We show that increasing fat mass is associated with increasing levels of sCD163, a circulating marker of macrophages also associated with inflammatory biomarkers. We thus hypothesize that adipose tissue macrophages may have a role in the proinflammatory state observed in patients with renal disease. Finally, we propose the term "uremic-metabolic syndrome" to describe this state of increased adipose tissue signaling in patients with uremia, a phenomenon that may share some characteristics with the metabolic syndrome of obesity.

Size matters: body composition and outcomes in maintenance hemodialysis patients

In hemodialysis patients a low body mass index (BMI) is correlated with an unfavorable clinical outcome, a phenomenon known as "reverse epidemiology". Mechanisms underlying this observation are unclear. We propose the following: uremic toxin generation occurs predominantly in visceral organs and the mass of key uremiogenic viscera (gut, liver) relative to body weight is higher in small people. Consequently, the rate of uremic toxin generation per unit of BMI is higher in patients with a low BMI. Body water, mainly determined by muscle mass, serves as a dilution compartment for uremic toxins. Therefore, the concentration of uremic toxins is higher in small subjects. Uremic toxins are taken up by adipose and muscle tissues, subsequently metabolized and stored. Thus, the larger the ratio of fat and muscle mass to visceral mass, the lower the concentration of uremic toxins and the better the survival. To test this hypothesis, studies on uremic toxin kinetics in relation to body composition are needed.

Reverse epidemiology in peritoneal dialysis patients: the Canadian experience and review of the literature

High Body Mass Index (BMI) has been associated with improved survival of End-Stage Renal Disease (ESRD) patients on chronic hemodialysis (HD); however, studies on the relationship of BMI with survival in Peritoneal Dialysis (PD) patients have yielded conflicting results. The purpose of this study was to evaluate the impact of BMI on survival of Canadian ESRD patients on PD, correcting for their age, sex, race, diabetes mellitus, and arterial hypertension. In an intent to treat study, we reviewed data of the Canadian Organ Replacement Register (CORR), of incident patients, starting PD between 1994 and 1998 and followed up from their initial PD treatment to the end of 2003. Patients were censored at loss to follow up, transplantation, and the end of the observation period. Cox regression (multivariate) analysis was performed and adjustments were made for age, gender, race, primary renal disease and BMI. During these years, 4054 patients commenced PD, 1742 (43%) of them were females and 1471 (36.3%) were diabetics. The majority were Caucasians (n=3058, 75.4%); 120 (3%) belonged to the First Nations, 137 (3.4%) were black, and the rest (739 pts-18.2%) belonged to various other ethnicities. Based on quartiles of the BMI distribution, 1130 patients (28%) had a BMI < 18.5 kg/m(2); 1163 (28.7%), 18.5-24.9 kg/m(2); 1214 (30%), 25-29.9 kg/m(2); 547 (13.5%) > 30 kg/m(2). Intent to treat Cox regression analysis showed that being underweight was a strong risk factor for death. Specifically, a BMI less than 18.5 was associated with a death hazard ratio (HR) 1.3, (CI: 1.1-1.6). On the contrary, BMI > 30 was not associated with worse survival than those with normal BMI (HR = 1.009, CI = 0.89-1.14). High-BMI patients should not be discouraged from PD just because of their size.

Obesity: a problem of darwinian proportions?

Obesity has been described as an abnormality arising from the evolution of man, who becomes fat during the time of perpetual plenty. From the perspective of "Darwinian Medicine," if famine is avoided, obesity will prevail. Problems regarding obesity arise within many disciplines, including socioeconomic environments, the educational system, science, law, and government. This article will discuss various ethical aspects of several disciplines regarding obesity, with a focus on scientific inquiry. We will discuss this within the categories: (1) chronic kidney disease predialysis, (2) dialysis, and (3) renal transplantation. This article aims to help nephrologists and their patients navigate through the ethical aspects of obesity and chronic kidney disease.

The kidney disease wasting: Inflammation, oxidative stress, and diet-gene interaction

The 350,000 maintenance hemodialysis (MHD) patients in the United States have an unacceptably high mortality rate of >20%/year. Almost half of all deaths are assumed to be cardiovascular. Markers of kidney disease wasting (KDW) such as hypoalbuminemia, anorexia, body weight and fat loss, rather than traditional cardiovascular risk factors, appear to be the strongest predictors of early death in these patients. The KDW is closely related to oxidative stress (SOX). Such SOX markers as serum myeloperoxidase are associated with pro-inflammatory cytokines and poor survival in MHD patients. Identifying the conditions that modulate the KDW/SOX-axis may be the key to improving outcomes in MHD patients. Dysfunctional lipoproteins such as a higher ratio of the high-density lipoprotein inflammatory index (HII) may engender or aggravate the KDW, whereas functionally intact or larger lipoprotein pools, as in hypercholesterolemia and obesity, may mitigate the KDW in MHD patients. Hence, a reverse epidemiology or "bad-gone-good" phenomenon may be observed. Diet and gene and their complex interaction may lead to higher proportions of pro-inflammatory or oxidative lipoproteins such as HII, resulting in the aggravation of the SOX and inflammatory processes, endothelial dysfunction, and subsequent atherosclerotic cardiovascular disease and death in MHD patients. Understanding the factors that modulate the KDW/SOX complex and their associations with genetic polymorphism, nutrition, and outcomes in MHD patients may lead to developing more effective strategies to improve outcomes in this and the 20 to 30 million Americans with chronic disease states such as individuals with chronic heart failure, advanced age, malignancies, AIDS, or cachexia.

Dietary recommendations for obese patients with chronic kidney disease

For optimal management of chronic kidney disease (CKD), dietary modification should be an integral part of patient care. Dietary considerations for obese patients with CKD are numerous and complicated and involve modification of intake of calories, protein, fat, phosphorus, and electrolytes. General principles for dietary management of obese patients include (1) ensuring adequate monitoring of nutritional status through assessment of diet, nutrition-related laboratory parameters, and anthropometrics; (2) creation of an individualized diet plan that meets clinical guidelines and has favorable effects on obesity-related conditions such as blood pressure and lipids; (3) careful attention to patients' food choices, portion size, and food-preparation methods; (4) recommending adjustment of overall energy intake to promote weight loss, yet maintain good nutritional status; and (5) modification of diet as the patient's nutritional status changes and CKD progresses. The basic objectives of dietary modification are to lighten the excretory load of products of metabolism and to help the kidney maintain normal equilibrium of the body's internal environment. Dietary modifications must be individualized and appropriate to the stage of CKD. This review describes dietary factors important in optimizing nutritional status of obese patients with CKD. Additionally, current clinical practice guidelines and strategies for meeting them are discussed.

Hepatitis C inflection in dialysis patients: a link to poor clinical outcome?

Among the 350,000 maintenance dialysis patients in the USA, the mortality rate is high (20-23% per year) as is the prevalence of hepatitis C virus (HCV) infection (5-15%). An additional same number of dialysis patients in the USA may be infected with HCV but have undetectable HCV antibodies. Almost half of all deaths in dialysis patients, including HCV-infected patients, are due to cardiovascular disease. Since over two-thirds of dialysis patients die within 5 years of initiating dialysis and because markers of malnutrition-inflammation complex syndrome (MICS), rather than traditional cardiovascular risk factors, are among the strongest predictors of early death in these patients, the impact of HCV infection on nutritional status and inflammation may be a main cause of poor survival in this population. Based on data from our cross-sectional and limited longitudinal studies, we hypothesize that HCV infection confounds the association between MICS and clinical outcomes in dialysis patients and, by doing so, leads to higher short-term cardiovascular events and death. Understanding the natural history of HCV and its association with inflammation, nutrition and outcomes in dialysis patients may lead to testing more effective anti-HCV management strategies in this and other similar patient populations, providing benefits not only for HCV infection but the detrimental consequences associated with this infection. In this article, we review the link between the HCV infection and mortality in dialysis patients and compare HCV antibody to molecular methods to detect HCV infection in these individuals.

Plasma Lipoprotein Abnormalities in Hemodialysis Patients—Clinical Implications and Therapeutic Guidelines

Patients with advanced stages of chronic kidney disease (CKD) have an increased risk of death from cardiovascular disease (CVD). Dyslipidemias are associated with atherosclerotic vascular changes and the risk of occurrence of acute myocardial infarction in hemodialysis patients. However, management of dyslipidemia in hemodialysis patients does not appear to be actively carried out in routine practice. Presumably, there are three reasons for this reluctance to lipid-lowering in hemodialysis patients. First, there are epidemiological data showing the inverse relationship between cholesterol and mortality rate; a high cholesterol predicts a better survival. Second, lipids are not usually measured using standard fasting serum, but a non-fasting specimen. Third, although hypertriglyceridemia is the most common abnormality, fibrates are contraindicated in patients with renal failure because of a high risk of rhabdomyolysis. These issues are discussed in the current review article. Based on published work, lipid lowering would not increase the death rate if carried out without worsening malnutrition. The National Kidney Foundation K/DOQI Clinical Practice Guidelines recommend a reduction in fasting LDL-C below 100 mg/dL for the prevention of CVD in dialysis patients. Practically, however, the use of non-HDL-C measured by casual blood samples might be sufficient for the risk assessment in many hemodialysis patients. Statins are a good choice for lipid-lowering in dialysis patients. Furthermore, lipoprotein profile might be improved by an inventive use of dialyzer membranes, dialysate solutions, and other dialysis-related medications. For severe hypercholesterolemia, LDL-apheresis is another choice for consideration. Further studies are needed to clearly prove the benefit of lipid reduction in hemodialysis patients and those with CKD at earlier stages.

Epidemiology of dialysis patients and heart failure patients

The epidemiology of maintenance dialysis patients and heart failure patients has striking similarities. Both groups have a high prevalence of comorbid conditions, a high hospitalization rate, a low self-reported quality of life, and an excessively high mortality risk, mostly because of cardiovascular causes. Observational studies in both dialysis and heart failure patients have indicated the lack of a significant association between the traditional cardiovascular risk factors and mortality, or the existence of a paradoxic or reverse association, in that obesity, hypercholesterolemia, and hypertension appear to confer survival advantages. The time discrepancy between the 2 sets of risk factors, that is, overnutrition (long-term killer) versus undernutrition (short-term killer) may explain the overwhelming role of malnutrition, inflammation, and cachexia in causing the reverse epidemiology, which may exist in more than 20 million Americans. We have reviewed the opposing views about the concept of reverse epidemiology in dialysis and heart failure patients, the recent Die Deutsche Diabetes Dialyze study findings, and the possible role of racial disparities. Contradictory findings on hyperhomocysteinemia in dialysis patients are reviewed in greater details as a possible example of publication bias. Additional findings related to intravenous iron and serum ferritin, calcium, and leptin levels in dialysis patients may enhance our understanding of the new paradigm. The association between obesity and increased death risk in kidney transplanted patients is reviewed as an example of the reversal of reverse epidemiology. Studying the epidemiology of dialysis patients as the archetypical population with such paradoxic associations may lead to the development of population-specific guidelines and treatment strategies beyond the current Framingham cardiovascular risk factor paradigm.

Body Composition and Cardiovascular Risk in Hemodialysis Patients

Death rate is unacceptably elevated in end-stage renal disease patients treated with hemodialysis. Excessive body fat, or obesity, is the well-known risk factor for cardiovascular disease and other health problems in the general population. However, hemodialysis patients with a higher body mass index (BMI) have a lower risk of death, as shown by many studies. There are several explanations for the paradox of BMI in dialysis patients. First, although body mass is composed of fat mass and fat-free mass (lean mass), it is unknown which is more important, fat mass or lean mass, in predicting outcome of hemodialysis patients. Second, it is also possible that functions of adipose tissue are altered in renal failure so that accumulation of body fat leads to less atherogenicity and beneficial properties become predominant. Third, an increased fat mass may be protective against death after harmful events. In this article, we explore these possibilities using either the data of our own cohort of hemodialysis patients or the existing registry data of Japan. We conclude that in hemodialysis patients, fat mass rather than lean mass plays a protective role against mortality, that the fat mass-adipocytokine relationship is altered, and that a low BMI is associated with increased risk of fatality after cardiovascular events rather than the risk of occurrence of such events.

Recent advances in understanding the malnutrition-inflammation-cachexia syndrome in chronic kidney disease patients: What is next?

Several recent clinical trials using single modalities to correct the conventional cardiovascular risk factors in patients with chronic kidney disease (CKD) or to improve dialysis dose and techniques in maintenance dialysis patients have failed despite the high rate of cardiovascular mortality in these individuals. Protein-energy malnutrition and inflammation, two relatively common and concurrent conditions in CKD patients, have been implicated as the main cause of poor short-term survival in this population. The "malnutrition-inflammation-cachexia syndrome" (MICS) appears to be the main cause of worsening atherosclerotic cardiovascular disease in the CKD population. The MICS is associated with low serum cholesterol and homocysteine levels and leads to "cachexia in slow motion." Hence a reverse epidemiology of cardiovascular risk factors is observed in dialysis patients with a paradoxical association of obesity, hypercholesterolemia, and hyperhomocysteinemia with better survival. Correction of MICS can potentially ameliorate the cardiovascular epidemic in CKD patients. Because MICS is multifactorial, its correction will require an integral approach rather than a single intervention. The ongoing obsession with conventional cardiovascular risk factors largely reflecting overnutrition in a population that suffers from the short-term consequences of undernutrition and excessive inflammation may well be fruitless. Clinical trials focusing on the causes and consequences of MICS and its modulation using nutritional interventions may be the key to improving survival in these individuals.

Increasing body mass index and obesity in the incident ESRD population

An increase in obesity prevalence among patients who initiate dialysis may influence the growth of the total ESRD population as a result of improved survival and decreased likelihood for transplantation. Temporal trends in mean body mass index (BMI) and obesity prevalence were examined among incident patients with ESRD by year of dialysis initiation between 1995 and 2002, and these trends were compared with those in the US population during this same period. Among incident dialysis patients, BMI was calculated with the height and estimated dry weight collected from the Centers for Medicare and Medicaid Services End-Stage Renal Disease Medical Evidence Form. In the US population, self-reported height and weight were used. Prevalence of total obesity and obesity stage > or =2 were defined as a BMI > or =30 and > or =35 kg/m(2), respectively. Among incident patients with ESRD, mean BMI increased from 25.7 to 27.5 kg/m(2), and total obesity and obesity stage > or =2 increased by 33 and 63%, respectively, among incident patients with ESRD (P < 0.0001 for obesity trends). BMI slope was approximately two-fold higher in the incident ESRD population compared with the US population for all age groups. However, temporal increases in obesity prevalence were similar between the two populations. As a result of the survival advantage associated with obesity and decreased likelihood for transplantation, these trends most likely will influence the total number of patients who receive dialysis in the next decade.

Association of body size with health status in patients beginning dialysis

BACKGROUND

Greater weight-for-height has been associated with prolonged survival in patients with end-stage renal disease (ESRD) but not in the general population. The association between body size and health status has not been carefully evaluated.

OBJECTIVES

We compared the self-reported health status of 2467 participants in the Dialysis Morbidity and Mortality Study Wave 2 by using body mass index (BMI; in kg/m2) to approximate body size and composition.

DESIGN

BMI was categorized into 4 groups (<19, 19 to <25, 25 to <30, and > or = 30) corresponding to World Health Organization criteria for underweight, normal-weight, overweight, and obese status. We adjusted for demographic, clinical, and laboratory factors that may have confounded the association between body size and health status.

RESULTS

Scores on the physical component summary and the physical functioning scale were significantly lower for obese subjects than for those with normal weight or moderately high BMI after adjustment for demographic factors, comorbidity, and laboratory markers of nutritional status. Mental component summary and symptom scores were unrelated to BMI. The underweight group scored lower on many Medical Outcomes Study 36-Item Short Form scales than did the normal-weight group.

CONCLUSIONS

Whereas higher BMI has consistently been associated with enhanced dialysis-related survival, health status-particularly physical function-may be impaired by obesity. Additional longitudinal studies of body weight and composition are needed for a better understanding of the complex effects of obesity and undernutrition in persons with ESRD and advanced chronic kidney disease.

Associations of body fat and its changes over time with quality of life and prospective mortality in hemodialysis patients

BACKGROUND

In maintenance hemodialysis (MHD) patients, a larger body size is associated with better survival but a worse self-reported quality of life (QoL). It is not clear whether muscle mass or body fat confers the survival advantage.

OBJECTIVE

We hypothesized that both a low baseline body fat percentage and a loss of fat over time were independently associated with higher mortality but with a better QoL score.

DESIGN

In 535 adult MHD patients, body fat was measured directly with the use of near infrared interactance and QoL was measured with a Short Form 36 questionnaire. The patients were followed for < or =30 mo.

RESULTS

Across four 12% increments of body fat at baseline, the reported QoL scores were progressively lower (P < 0.01). After a multivariate adjustment for demographics and surrogates of muscle mass and inflammation (ie, midarm muscle circumference, serum creatinine, and proinflammatory cytokines), 46 patients with body fat of <12% had a death hazard ratio (HR) 4 times that of 199 patients with body fat content between 24% and 36% (HR: 4.01; 95% CI: 1.61, 9.99; P = 0.003). In 411 MHD patients whose body fat was remeasured after 6 mo, a fat loss (< or =-1%) was associated with a death risk 2 times that of patients who gained fat (> or =1%) after a multivariate adjustment (HR: 2.06; 95% CI: 1.05, 4.05; P = 0.04).

CONCLUSIONS

A low baseline body fat percentage and fat loss over time are independently associated with higher mortality in MHD patients even after adjustment for demographics and surrogates of muscle mass and inflammation, whereas a tendency toward a worse QoL is reported by MHD patients with a higher body fat percentage. Obesity management in dialysis patients may need reconsideration.

Association between serum bicarbonate and death in hemodialysis patients: is it better to be acidotic or alkalotic?

The optimal acid-base status for survival in maintenance hemodialysis (MHD) patients remains controversial. According to recent reports, acidosis is associated with improved survival in MHD patients. It was hypothesized that this inverse association is due to a confounding effect of the malnutrition-inflammation complex syndrome (MICS). Associations between baseline (first 3 mo averaged) predialysis serum bicarbonate (HCO3(-)) and 2-yr mortality were examined in 56,385 MHD patients who were treated in virtually all DaVita dialysis clinics across the United States. The range of HCO3(-) was divided into 12 categories (< 17, > or = 27, and 10 groups in between). Three sets of Cox regression models were evaluated to estimate hazard ratios of all-cause and cardiovascular death in both incident and prevalent patients: (1) Unadjusted, (2) multivariate case mix adjusted (which also included dialysate HCO3(-) and Kt/V), and (3) adjusted for case mix and nine markers of MICS (body mass index; erythropoietin dose; protein intake; serum albumin; creatinine; phosphorus; calcium; ferritin and total iron binding capacity; and blood hemoglobin, WBC, and lymphocytes). There were significant inverse associations between serum HCO3(-) and serum phosphorus and estimated protein intake. The lowest unadjusted mortality was associated with predialysis HCO3(-) in the 17- to 23-mEq/L range, whereas values > or = 23 mEq/L were associated with progressively higher all-cause and cardiovascular death rates. This association, however, reversed after case-mix and MICS multivariate adjustment, so that HCO3(-) values >22 mEq/L had lower death risk. Although previous epidemiologic studies indicated an association between high serum HCO3(-) and increased mortality in MHD patients, this effect seems to be due substantially to the effect of MICS on survival.

Association of morbid obesity and weight change over time with cardiovascular survival in hemodialysis population

BACKGROUND

In maintenance hemodialysis (MHD) outpatients, a reverse epidemiology is described, ie, baseline obesity appears paradoxically associated with improved survival. However, the association between changes in weight over time and prospective mortality is not known.

METHODS

Using time-dependent Cox models and adjusting for changes in laboratory values over time, the relation of quarterly-varying 3-month averaged body mass index (BMI) to all-cause and cardiovascular mortality was examined in a 2-year cohort of 54,535 MHD patients from virtually all DaVita dialysis clinics in the United States.

RESULTS

Patients, aged 61.7 +/- 15.5 (SD) years, included 54% men and 45% with diabetes. Time-dependent unadjusted and multivariate-adjusted models, based on quarterly-averaged BMI controlled for case-mix and available time-varying laboratory surrogates of nutritional status, were calculated in 11 categories of BMI. Obesity, including morbid obesity, was associated with better survival and reduced cardiovascular death, even after accounting for changes in BMI and laboratory values over time. Survival advantages of obesity were maintained for dichotomized BMI cutoff values of 25, 30, and 35 kg/m2 across almost all strata of age, race, sex, dialysis dose, protein intake, and serum albumin level. Examining the regression slope of change in weight over time, progressively worsening weight loss was associated with poor survival, whereas weight gain showed a tendency toward decreased cardiovascular death.

CONCLUSION

Weight gain and both baseline and time-varying obesity may be associated with reduced cardiovascular mortality in MHD patients independent of laboratory surrogates of nutritional status and their changes over time. Morbidly obese patients have the lowest mortality. Clinical trials need to verify these observational findings.

Kidney insufficiency and nutrient-based modulation of inflammation

PURPOSE OF REVIEW

Patients with chronic kidney disease have a high cardiovascular mortality rate. Despite recent advances in dialysis techniques, over 20% of US dialysis patients die every year. Protein-energy malnutrition and inflammation are common and usually concurrent in chronic kidney disease patients, and have been implicated as the main cause of high mortality. We reviewed the pathophysiology of the malnutrition-inflammation complex syndrome and its potential modulation by dietary and other nutritional interventions in chronic kidney disease patients.

RECENT FINDINGS

The malnutrition-inflammation complex syndrome is a main cause of the atherosclerotic cardiovascular disease epidemic in chronic kidney disease. This may be by virtue of the syndrome's inflammatory components. Malnutrition and inflammation lead to weight loss over time, i.e. cachexia in slow motion, and result in decreased serum cholesterol and homocysteine levels. A 'reverse epidemiology' of cardiovascular risk factors is observed in chronic kidney disease, in that obesity, hypercholesterolemia and hyperhomocysteinemia are paradoxically associated with better survival. Among the possible etiologies of the malnutrition-inflammation complex syndrome, anorexia, low nutrient intake and oxidative stress are theoretically amenable to dietary modulation; however, the bulk of findings are epidemiological.

SUMMARY

There is no consensus as to how to correct the malnutrition-inflammation complex syndrome in chronic kidney disease patients. Because the malnutrition-inflammation complex syndrome is multifactorial, its correction probably requires a battery of simultaneous interventions, rather than one single modality. Clinical trials focusing on the syndrome are currently non-existent and are therefore urgently required to improve poor clinical outcome in chronic kidney disease patients.