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Until recently, it was not apparent whether apparent paradoxical associations of body mass index (BMI), lipids, and blood pressure with survival observed in hemodialysis (HD) patients, which contradict observations from the general population, also applied to peritoneal dialysis (PD) patients. Studies of survival in PD patients must account for differences in adjusted survival relative to HD patients, namely, early equivalent to superior survival, but after about 1-2 years, inferior survival. Several recent observational studies have analyzed the association between BMI and survival in PD patients from different perspectives and using different patient populations. In general, these studies found that any survival advantage associated with obesity is significantly less likely in PD than HD patients. Among PD patients, those who are obese can be said to have equivalent survival to PD patients with normal BMI. Studies of lipids and blood pressure in PD patients also yield conflicting associations with survival. Obese patients, especially if diabetic, may have increased risk of death after starting on PD compared to HD, although firm conclusions are premature given the limitations of current evidence. At present, the levels of lipids and blood pressure which are best associated with survival in PD patients are not well-defined.
Semin Dial
PMID:Body mass index and peritoneal dialysis: "exceptions to the exception" in reverse epidemiology? 1799 Dec 5

The term "reverse epidemiology" has been proposed to address the apparent different relationship between numerous risk factors and outcomes among dialysis patients: thus, obesity, hypertension, high cholesterol, and elevated creatinine all appear to be associated with decreased risk. Since this is contrary to the general findings in otherwise healthy populations, some kind of "reversal" has been suggested, that would be contrary to classical epidemiology. The authors describe several faults to this conception. The rules of epidemiology have not been reversed in dialysis patients. In fact, the complexity of the population implies a greater need for attention to the distinction between association and causation and the importance of confounding and bias. In particular existing subclinical and clinical disease which is very common among dialysis patients can change associations so drastically that they are dominated by different causal pathways than those seen in the general population. For example, lower cholesterol is a better marker of poor health than of a healthy diet and thus is associated with different outcomes. To the extent the term reverse epidemiology implies either epidemiology or biology is different in dialysis patients it can be misleading and detrimental. The differences between risk factors in end-stage renal disease (ESRD) and other individuals are surely important, but can themselves be the basis of excellent epidemiology, applied with the classic rules developed for this discipline with the goal of uncovering causal association and hypotheses to be tested in clinical trials.
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PMID:Reverse epidemiology: a confusing, confounding, and inaccurate term. 1799 Dec 9

The term "reverse epidemiology" is used to indicate that such surrogates of cardiovascular risk and metabolic syndrome as obesity, hypercholesterolemia and hypertension are paradoxically associated with greater survival in individuals with chronic disease states and wasting, including dialysis patients, in whom the short-term survival is the issue at hand. It is being debated whether the crossing curves of the obesity-mortality association in dialysis patients vs. the general population reflect the residual confounding that needs to be controlled away statistically, or whether they have biological plausibility in sharp contradistinction to the currently dominating Framingham paradigm. In the rush to define the crossing curves as statistical artifact and to dismiss the term "reverse epidemiology" as a misnomer, we may miss the opportunity to gain information housed in those crossing lines and may miss the bigger picture, i.e., how to improve longevity in dialysis patients. Even though some of the survival paradoxes in dialysis patients appear to fulfill the Hill's criteria of causation, there are still two major drawbacks: (1) convincing pathophysiologic pathways to link dialysis patient survival to obesity, fat accumulation, higher serum lipoprotein levels or slightly higher than normal blood pressure values are yet to be verified in animal and other scientifically sound models; and (2) randomized controlled trials need to show that nutritional interventions resulting in weight gain can lead to greater survival in dialysis patients. Studying the survival paradoxes may lead to a paradigm shift by establishing targets beyond the Framingham guidelines for populations with chronic disease states.
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PMID:What is so bad about reverse epidemiology anyway? 1799 Dec 10

The human body can be roughly divided into two major compartments, fat mass and lean body mass. Adipose tissue is now considered to be a highly active tissue and, in addition to storing calories as triglycerides, it also secretes a large variety of compounds, including cytokines, chemokines and hormone-like factors such as leptin, adiponectin and resistin. On the other hand, muscle plays a central role in whole-body protein metabolism by serving as the principal provider for amino acids to maintain protein synthesis in vital tissues and organs and by providing hepatic gluconeogenic precursors. Although not a good indicator of body composition, the Quetelet index, also called body mass index (BMI), is often used for practical reasons. It is well known that high BMI predicts mortality and cardiovascular disease (CVD) in the general population. However, observational reports in the dialysis population have suggested that obesity is associated with improved survival, a phenomenon that is not well understood and subject to controversies. This review describes the characteristics of BMI in the general population and in chronic kidney disease (CKD) patients, as well as the respective role of muscle, whole body fat and fat distribution towards mortality, with particular emphasis on patients with CKD.
Nephrol Dial Transplant 2008 Aug
PMID:Body mass index, muscle and fat in chronic kidney disease: questions about survival. 1839 May 66

Arteriovenous fistulae (AVF) are widely regarded as the preferred vascular access in hemodialysis patients due to their primary patency and patient survival benefits. While the obesity paradox has been associated with improved cardiovascular morbidity and all-cause mortality in dialysis patients, its long-term vascular access outcomes are less clear. Recent literature has suggested that obese patients may have increased early and late fistula failure. The purpose of this study was to explore the relationships between obesity and vascular access outcomes. We performed a retrospective cohort analysis using the USRDS DMMS Wave 2 data set. All incident dialysis patients as of January 1, 1996, over the age of 18, receiving only hemodialysis as mode of renal replacement therapy were eligible for inclusion. Among other variables, data collected for the DMMS Wave 2 included: type and location of vascular access, AVF maturity, vascular access revision, and failure. Logistic regression analyses were used to examine the relationships between obesity and vascular access outcomes, adjusting for important covariates. In all, 1486 hemodialysis patients were included. Using body mass index (BMI) <30 kg/m(2) as reference, obesity did not emerge as a factor in predicting vascular access revisions or failures. An increased risk of AVF failure to mature was found only in the highest BMI quartile (>or=35 kg/m(2)) (aOR 3.66 [95% CI 1.27-10.55], p = 0.017). Peripheral vascular disease was independently associated with an increased risk of AVF failure (aOR 2.78 [95% CI 1.01-7.63], p = 0.047) and arteriovenous graft (AVG) failure (aOR 1.65 [95% CI 1.03-2.64], p = 0.036). Obesity was not associated with increased AVF or AVG revision rates or failure and only associated with poorer AVF maturity at highest BMI quartile. We conclude that obesity should not preclude placement of AVF as vascular access of choice, except in the very obese where assessment should be individually based.
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PMID:Obesity as a predictor of vascular access outcomes: analysis of the USRDS DMMS Wave II study. 1839 5

Central venous catheter (CVC) use at hemodialysis (HD) initiation remains high, despite reports of CVC-associated morbidity and mortality, and efforts at early arteriovenous fistula placement. In order to determine predictors of CVC use at the start of HD, data from the end-stage renal disease (ESRD) Clinical Performance Measures (CPM) Project was linked to the Centers for Medicare & Medicaid Services Medical Evidence (2728) Form. Of the 4071 incident hemodialysis patients in study years 1999-2003, 71.6% used a CVC at dialysis initiation. After controlling for demographic and co-morbid variables, patients with a CVC were 24% more likely to be female (p = 0.006), and 38% more likely to have ischemic heart disease (p = 0.002), while those with obesity (BMI > or = 30) were 24% less likely to start dialysis with a CVC (p = 0.006). Pre-ESRD hypoalbuminemia (< 3.5 g/dl) was associated with a twofold higher risk of CVC use (p = < 0.001), while patients with pre-ESRD anemia (hgb < 11 g/dl) were 29% more likely to use a CVC at dialysis initiation (p = 0.006) compared to those with hemoglobin > or = 11 g/dl. Patients receiving predialysis erythropoietin had a 41% lower odds of CVC use at dialysis initiation (p = < 0.001). Finally, dialysis year was predictive of CVC use; in 2002, 76% of patients initiated dialysis with a CVC compared with 66% in 1998 (p < 0.001). Overall, female gender, ischemic heart disease, lack of obesity, factors suggesting poor pre-ESRD care, and successive year of dialysis initiation were predictive of CVC use at hemodialysis initiation.
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PMID:Predictors of central venous catheter use at the initiation of hemodialysis. 1856 68

We report a case of a woman with secondary oxalosis after jejunoileal bypass surgery for obesity, who presented with oxalate stone disease and renal insufficiency requiring dialysis. Thirty years after surgery, longstanding osteoarticular symptoms were recognized as oxalate arthritis. Eventually, she also developed oxalate vasculitis, which improved with corticoid treatment and intensification of dialysis. Work-up for kidney transplantation revealed AA amyloidosis on gastric and colonic biopsies. Since no other cause of chronic inflammation could be identified, it was concluded that the amyloidosis was secondary to oxalate arthritis and vasculitis. To our knowledge, this is the first report on this association.
Nephrol Dial Transplant 2008 Oct
PMID:AA amyloidosis due to chronic oxalate arthritis and vasculitis in a patient with secondary oxalosis after jejunoileal bypass surgery. 1863 90

Metabolic syndrome (MetS) is defined as a cluster of risk factors for type 2 diabetes and cardiovascular disease; it is also an independent risk factor for developing chronic kidney disease (CKD) in the general population. Therefore, CKD has many similarities and associations with MetS, and the individual risk factors constituting MetS-especially insulin resistance and glucose intolerance, hypertension, dyslipidemia, and obesity-are also common features of the early stages of CKD. In the later stages of CKD, uremia per se and uremic complications such as fluid retention, protein-energy wasting, inflammation, and oxidative stress further contribute to an increase in the prevalence of MetS in CKD patients. In addition, PD patients exposed to glucose-based PD fluids have an increased risk of developing metabolic complications. The broad use of MetS in clinical research has raised the awareness of the public and of individual patients concerning the value of lifestyle interventions. However, the definition and pathogenesis of MetS are still debated, and no standardized definition nor proven prognostic value has been established for MetS as a cluster of risk factors for diabetes or cardiovascular disease in PD patients. Furthermore, considering the paradoxical associations of some of the risk factors in MetS with decreased mortality, another set of risk factors-those specific to patients with uremia (for example, inflammation and malnutrition)-and the appropriate cut-off levels to individual MetS risk factors should be taken account at the same time. Also, the benefit of interventions targeting these risk factors should be clarified in further clinical studies.
Perit Dial Int 2009 Feb
PMID:Definition of metabolic syndrome in peritoneal dialysis. 1927 Feb 3

The continuous quality improvement approach in peritoneal dialysis practice necessitates definition of the factors and the procedures that may possibly be contributing to the final success of peritoneal dialysis. The philosophy of continuous quality improvement uses the Plan, Do, Check, Act (PDCA) cycle. To improve the procedures used during peritoneal dialysis, the first step is to create a plan, then to carry out the plan, to check it, and after the collection of satisfactory information, to execute the chosen improvement action. Several studies have identified the most frequent causes of transfer from PD to HD as infection, catheter problems, inadequate dialysis, and psychosocial factors, among others. According to training guidelines from the International Society for Peritoneal Dialysis, seven points are of major importance to decrease infection risks: exit-site care, catheter placement, antibiotic prophylaxis for procedures, prevention of bowel-source peritonitis, prevention of fungal peritonitis, and connection methods. On the other hand, other factors such as hypoalbuminemia, depression, and obesity should also be taken into consideration for better technique survival in peritoneal dialysis patients.
Perit Dial Int 2009 Feb
PMID:Improving technique survival in peritoneal dialysis: what is modifiable? 1927 Feb 36

Both in the United States and many regions of the world, chronic kidney disease and end-stage renal disease (ESRD) in patients with diabetes mellitus have reached epidemic proportions in recent years. The large prevalent diabetic ESRD population in the US involves remarkable risk in African Americans and an increasing population of elderly diabetic patients, including many octogenarians. In the US and globally, over 90% of diabetic ESRD patients have type 2 diabetes. The multinational epidemic of diabetic ESRD has been linked to increases in the prevalence of diabetes in many populations, related to obesity, ageing, and physical inactivity. It is anticipated that the worldwide prevalence of diabetes over the next 20 years will reach a level twice that of the year 2000. The excessive morbidity and mortality of the diabetic ESRD population are well documented. However, the growth in incidence and prevalence rates for diabetic ESRD has remained somewhat stable in the US in recent years, and new data suggest that the incidence of ESRD expressed per diabetic population may finally be declining, suggesting that proven therapies are making "progress on progression."
Semin Dial
PMID:Diabetic CKD/ESRD 2010: a progress report? 2021 Sep 17


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