Diets and enteral supplements for improving outcomes in chronic kidney disease

Abstract

Protein-energy wasting (PEW), which is manifested by low serum levels of albumin or prealbumin, sarcopenia and weight loss, is one of the strongest predictors of mortality in patients with chronic kidney disease (CKD). Although PEW might be engendered by non-nutritional conditions, such as inflammation or other comorbidities, the question of causality does not refute the effectiveness of dietary interventions and nutritional support in improving outcomes in patients with CKD. The literature indicates that PEW can be mitigated or corrected with an appropriate diet and enteral nutritional support that targets dietary protein intake. In-center meals or oral supplements provided during dialysis therapy are feasible and inexpensive interventions that might improve survival and quality of life in patients with CKD. Dietary requirements and enteral nutritional support must also be considered in patients with CKD and diabetes mellitus, in patients undergoing peritoneal dialysis, renal transplant recipients, and in children with CKD. Adjunctive pharmacological therapies, such as appetite stimulants, anabolic hormones, and antioxidative or anti-inflammatory agents, might augment dietary interventions. Intraperitoneal or intradialytic parenteral nutrition should be considered for patients with PEW whenever enteral interventions are not possible or are ineffective. Controlled trials are needed to better assess the effectiveness of in-center meals and oral supplements.

Figure 1

Baseline serum albumin concentration and survival in patients on hemodialysis. Mortality predictability of 3-month averaged serum albumin levels in 58,058 patients on hemodialysis from 524 DaVita dialysis facilities in the USA. Case-mix-adjusted covariates included age, sex, diabetes mellitus, African-American race, Hispanic ethnicity, and dialysis vintage. The arrows and numbers indicate the incremental increase in mortality risk compared with the previous group. Abbreviation: HR, hazard ratio. Data obtained from Kalantar-Zadeh, K. et al. Nephrol. Dial. Transplant. 20, 1880–1888 (2005).

Figure 2

Change in serum albumin levels and survival in hemodialysis patients. Association of the change in serum albumin concentration over two consecutive calendar quarters with subsequent mortality over 2 years in 30,827 patients on maintenance hemodialysis. Abbreviations: HR, hazard ratio; MICS, malnutrition– inflammation complex syndrome. Kalantar-Zadeh, K. et al. Revisiting mortality predictability of serum albumin in the dialysis population: time dependency, longitudinal changes and population-attributable fraction. Nephrol. Dial. Transplant. (2005) 20 (9), 1880–1888 © by permission of Oxford University Press.

Figure 3

Effect of nutritional therapy modality on forearm muscle homeostasis. Metabolism of forearm muscle protein before, during and after hemodialysis, comparing controls, IDPN, and ONS in eight patients with deranged nutritional status. Skeletal muscle protein homeostasis during hemodialysis improved with both IDPN and ONS versus control (P = 0.005 and P = 0.009, respectively). ONS resulted in persistent anabolic benefits in the posthemodialysis phase when anabolic benefits of IDPN had dissipated. *P <0.05 versus control. Abbreviations: IDPN, intradialytic parenteral nutrition; ONS, oral nutritional support. Data obtained from Pupim, L. B., Majchrzak, K. M., Flakoll, P. J. & Ikizler, T. A. J. Am. Soc. Nephrol. 17, 3149–3157 (2006).

Figure 4

Serum albumin concentration and survival in patients with nondialysis-dependent CKD. Unadjusted and multivariable-adjusted all-cause mortality associated with various categories of serum albumin level in 1,220 US veterans with nondialysis-dependent CKD. Most patients had CKD stage 3 (56%) and stage 4 (30%), with fewer patients having CKD stage 1 (1%), stage 2 (7%), and stage 5 (5%). Adjustments were made for age, race, Charlson comorbidity index, etiology of CKD, diabetes mellitus, cardiovascular disease, smoking, systolic and diastolic blood pressure, BMI, estimated glomerular filtration rate, serum levels of calcium, phosphorus, hemoglobin, bicarbonate, cholesterol, and 24 h urine protein. Abbreviations: CKD, chronic kidney disease; HR, hazard ratio. Permission obtained from Kovesdy, C. P., George, S. M., Anderson, J. E. & Kalantar-Zadeh, K. Am. J. Clin. Nutr. 90, 407–414 (2009).

Figure 5

Proposed algorithm for enteral nutritional support in patients with CKD. The target of total protein intake should be a DPI of ≥1.2 g/kg per day for patients on dialysis, and 0.6 g/kg per day for patients with nondialysis-dependent CKD, including renal transplant recipients. Abbreviations: CKD, chronic kidney disease; DEI, dietary energy intake; DPI, dietary protein intake; IDPN, intradialytic parenteral nutrition; K, potassium; MIS, malnutrition–inflammation score; Na, sodium; P, phosphorus; PEG, percutaneous endoscopic gastrostomy; RTR, renal transplant recipient; SGA, subjective global assessment.