Purpose of review

Diet plays an important role in slowing progression of chronic kidney disease in native and transplanted kidneys. There is limited evidence on the association on dietary intake with renal allograft function. Mechanisms of major nutrients and dietary patterns with focusing on a plant-based diet related to kidney transplant health and longevity are reviewed.

Recent findings

High dietary protein intake may adversely affect renal allograft. Low protein plant-focused diets such as Dietary Approaches to Stop Hypertension, plant-dominant low-protein diet and Mediterranean diets appear associated with favorable outcomes in slowing renal allograft function decline. The mechanism may be related to a change in renal hemodynamic by decreasing glomerular hyperfiltration from low dietary protein intake and plant-based ingredients. Recent observational studies of association between dietary protein intake and kidney allograft outcomes are conflicting. Although strong evidence is still lacking, a low protein diet of 0.6-0.8 g/kg/day with at least 50% of the protein source from plant-based components in kidney transplant recipients with stable kidney allograft function should be considered as the dietary target.

Summary

Dietary intervention with low-protein plant-focused meals may improve outcomes in kidney transplant recipients, but the evidence remains limited and further studies are warranted.

Background and objectives

Unlike hemodialysis (HD), peritoneal dialysis (PD) is a continuous therapy and does not induce myocardial stunning. Yet, the death risk in HD and PD patients is similar. This study tested the hypothesis that serum potassium abnormalities contribute more to the death risk in PD patients than in HD patients.

Design, setting, participants, & measurements

Data from patients treated in DaVita facilities between July 1, 2001 and June 30, 2006 (n=10,468 PD patients; n=111,651 HD patients) were used to determine association of serum potassium with mortality.

Results

PD patients were significantly more likely to have serum potassium < 4 mEq/L, with an adjusted odds ratio of 3.30 (95% confidence interval [95% CI], 3.05, 3.56). There was a U-shaped relationship between time-averaged serum potassium and all-cause and cardiovascular mortality of PD patients, with adjusted hazards ratios of 1.51 for all-cause mortality for potassium < 3.5 mEq/L (95% CI, 1.29, 1.76) and 1.52 for potassium ≥ 5.5 mEq/L (95% CI, 1.32, 1.75). The population-attributable risks for all-cause mortality for serum potassium < 4.0 and ≥ 5.5 mEq/L were 3.6% and 1.9%, respectively, in PD patients, and 0.8% and 1.5%, respectively, in HD patients.

Conclusions

Abnormalities in serum potassium contribute disproportionately to the high death risk in PD patients. This may, in part, account for the equivalent cardiac risk seen with the two therapies.

Background and objectives

Interventional trials and some observational studies show target hemoglobin >13 g/dl to be associated with higher mortality in erythropoiesis-stimulating agent-treated (ESA-treated) hemodialysis patients; data for peritoneal dialysis (PD) patients are limited.

Design, setting, participants, & measurements

We tested our hypothesis that higher and lower achieved hemoglobin levels are associated with increased mortality in 9269 ESA-treated PD patients from all DaVita dialysis clinics during the time period July 2001 through June 2006 followed through June 2007 using a time-dependent analysis.

Results

Lower hemoglobin was associated with significantly higher all-cause mortality in ESA-treated PD patients: with hemoglobin of 11.0 to <12.0 g/dl as reference, the time-dependent adjusted death hazard ratios for hemoglobin levels of 10.0 to <11.0, 9.0 to <10.0, and ≤9.0 g/dl were 1.12 (1.00 to 1.24), 1.30 (1.12 to 1.50), and 1.38 (1.14 to 1.67), respectively. The time-dependent adjusted hazard ratios for cardiovascular death with hemoglobin levels of 10.0 to <11.0, 9.0 to <10.0, and ≤9.0 g/dl were 1.11 (0.93 to 1.32), 1.37 (1.09 to 1.72), and 1.12 (0.79 to 1.57), respectively. The same trend for association of lower hemoglobin level with higher mortality was seen in African-American and non-African American men and women. In contrast, there was no association between higher achieved hemoglobin and all-cause or cardiovascular mortality in ESA-treated PD patients.

Conclusions

Lower, but not higher, achieved hemoglobin is associated with higher mortality in ESA-treated PD patients. Randomized controlled trials are needed to examine the target hemoglobin level with lowest mortality in PD patients.

Mineral and bone diseases (MBD) are common in patients with chronic kidney disease who undergo kidney transplantation. The incidence, types and severity of MBD vary according to the duration of chronic kidney disease, presence of comorbid conditions and intake of certain medications. Moreover, multiple types of pathology may be responsible for MBD. After successful reversal of uremia by kidney transplantation, many bone and mineral disorders improve, while immunosuppression, other medications, and new and existing comorbidities may result in new or worsening MBD. Chronic kidney disease is also common after kidney transplantation and may impact bone and mineral disease. In this article, we reviewed the prevalence, pathophysiology, and impact of MBD on post-transplant outcomes. We also discussed the diagnostic approach; immunosuppression management and potential treatment of MBD in kidney transplant recipients.

The association between restless legs syndrome (RLS) and Parkinson's disease (PD) has been extensively studied with inconclusive results; therefore, we prospectively examined the associations of the presence of RLS with development of incident PD. From a nationally representative prospective cohort of almost 3.5 million US veterans (age: 60 ± 14 years, 93% male, median follow-up time of 7.8 years [interquartile range: 6.4-8.4 years]), we created a propensity-matched cohort of 100882 PD-free patients and examined the association between prevalent RLS and incident PD. This association was also assessed in the entire cohort. Associations were examined using Cox models. There were 68 incident PD events (0.13%, incidence rate 1.87 [1.48-2.37]/10000 patient-years) in the RLS-negative group, and 185 incident PD events (0.37%, incidence rate 4.72 [4.09-5.45]/10000 patient-years) in the RLS-positive group in the propensity-matched cohort. Prevalent RLS was associated with more than twofold higher risk of incident PD (hazard ratio [HR]: 2.57, 95% confidence interval [CI]: 1.95-3.39) compared to RLS-negative patients. Qualitatively similar results were found when we examined the entire 3.5 million cohort: Prevalent RLS was associated with more than twofold higher risk of incident PD (multivariable adjusted HR: 2.81, 95%CI: 2.41-3.27). RLS and PD share common risk factors. In this large cohort of US veterans, we found that prevalent RLS is associated with higher risk of incident PD during 8 years of follow-up, suggesting that RLS could be an early clinical feature of incident PD.