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.

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.

Background

Peritoneal dialysis (PD) provides outcomes similar to hemodialysis, but its use has decreased in the United States despite its potential for substantial taxpayer savings. We undertook this study to determine the relationship between dialysis unit ownership with PD use and outcomes.

Study design

Observational study.

Setting & participants

All incident dialysis patients (1996 to 2004) from the US Renal Data System.

Predictor

Large dialysis organization (LDO), defined as corporations owning 20 or more freestanding dialysis units located in more than 1 state.

Outcomes & measurements

Odds for an incident dialysis patient undergoing PD and hazards for death on follow-up in incident PD patients for each of the 5 LDOs (non-LDO as reference).

Results

During the 9-year period, 785,531 patients started maintenance dialysis therapy; the proportion receiving care in LDOs increased from 39% to 63%. There were consistent differences in PD use. It was significantly lower in LDO 2 (adjusted odds ratio [OR], 0.66; 95% confidence interval [CI], 0.64 to 0.68), LDO 3 (OR, 0.82; 95% CI, 0.80 to 0.85), and LDO 4 (OR, 0.96; 95% CI, 0.92 to 0.995) and higher in LDO 1 (adjusted OR, 1.06; 95% CI, 1.02 to 1.11) and LDO 5 (adjusted OR, 1.09; 95% CI, 1.06 to 1.12). Between 2000 and 2004, LDO 2 had the least use and greatest risk of death (hazard ratio, 1.08; 95% CI, 1.02 to 1.14); LDO 1 had greater use and the lowest death risk (hazard ratio, 0.87; 95% CI, 0.78 to 0.96).

Limitations

Only cross-sectional associations can be described.

Conclusions

Three of the 5 LDOs had consistently lower PD use. Patients treated in the LDO with the lowest use of PD had the greatest risk of death. Understanding relationships among providers, physicians, and dialysis modality use may help devise strategies for increasing PD use in appropriate patients. This has the potential to reduce the cost of renal replacement therapy and further improve outcomes.

In the United States, chronic peritoneal dialysis take-on has declined among incident ESRD patients. Although increasing age, co-morbidity, and body size may explain part of this decline, other factors likely contribute. Among incident ESRD patients in the United States, we found that peritoneal dialysis take-on significantly decreased from 11% in 1996 to 1997 to 7% in 2002 to 2003 (P < 0.001 for the trend). This decrease remained after adjusting for patient demographics, case-mix, and laboratory data, suggesting the involvement of other factors. This decline in utilization occurred during a time of improving outcomes for incident peritoneal dialysis patients, measured as reduced hazards for death or for the need to transfer to hemodialysis. In contrast, among patients initially treated with hemodialysis, the 12-month adjusted hazards for death or transfer to peritoneal dialysis slightly worsened or were unchanged over this same period. Therefore, the decline in peritoneal dialysis take-on cannot be entirely explained by increasing age, co-morbidity and body size of incident ESRD patients. The decline in utilization has occurred at a time when the early outcomes of CPD patients have improved.