Dietary interventions for adults with chronic kidney disease

Abstract

Background: Dietary changes are routinely recommended in people with chronic kidney disease (CKD) on the basis of randomised evidence in the general population and non-randomised studies in CKD that suggest certain healthy eating patterns may prevent cardiovascular events and lower mortality. People who have kidney disease have prioritised dietary modifications as an important treatment uncertainty.

Objectives: This review evaluated the benefits and harms of dietary interventions among adults with CKD including people with end-stage kidney disease (ESKD) treated with dialysis or kidney transplantation.

Search methods: We searched the Cochrane Kidney and Transplant Specialised Register (up to 31 January 2017) through contact with the Information Specialist using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE, and EMBASE; handsearching conference proceedings; and searching the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

Selection criteria: Randomised controlled trials (RCTs) or quasi-randomised RCTs of dietary interventions versus other dietary interventions, lifestyle advice, or standard care assessing mortality, cardiovascular events, health-related quality of life, and biochemical, anthropomorphic, and nutritional outcomes among people with CKD.

Data collection and analysis: Two authors independently screened studies for inclusion and extracted data. Results were summarised as risk ratios (RR) for dichotomous outcomes or mean differences (MD) or standardised MD (SMD) for continuous outcomes, with 95% confidence intervals (CI) or in descriptive format when meta-analysis was not possible. Confidence in the evidence was assessed using GRADE.

Main results: We included 17 studies involving 1639 people with CKD. Three studies enrolled 341 people treated with dialysis, four studies enrolled 168 kidney transplant recipients, and 10 studies enrolled 1130 people with CKD stages 1 to 5. Eleven studies (900 people) evaluated dietary counselling with or without lifestyle advice and six evaluated dietary patterns (739 people), including one study (191 people) of a carbohydrate-restricted low-iron, polyphenol enriched diet, two studies (181 people) of increased fruit and vegetable intake, two studies (355 people) of a Mediterranean diet and one study (12 people) of a high protein/low carbohydrate diet. Risks of bias in the included studies were generally high or unclear, lowering confidence in the results. Participants were followed up for a median of 12 months (range 1 to 46.8 months).Studies were not designed to examine all-cause mortality or cardiovascular events. In very-low quality evidence, dietary interventions had uncertain effects on all-cause mortality or ESKD. In absolute terms, dietary interventions may prevent one person in every 3000 treated for one year avoiding ESKD, although the certainty in this effect was very low. Across all 17 studies, outcome data for cardiovascular events were sparse. Dietary interventions in low quality evidence were associated with a higher health-related quality of life (2 studies, 119 people: MD in SF-36 score 11.46, 95% CI 7.73 to 15.18; I2 = 0%). Adverse events were generally not reported.Dietary interventions lowered systolic blood pressure (3 studies, 167 people: MD -9.26 mm Hg, 95% CI -13.48 to -5.04; I2 = 80%) and diastolic blood pressure (2 studies, 95 people: MD -8.95, 95% CI -10.69 to -7.21; I2 = 0%) compared to a control diet. Dietary interventions were associated with a higher estimated glomerular filtration rate (eGFR) (5 studies, 219 people: SMD 1.08; 95% CI 0.26 to 1.97; I2 = 88%) and serum albumin levels (6 studies, 541 people: MD 0.16 g/dL, 95% CI 0.07 to 0.24; I2 = 26%). A Mediterranean diet lowered serum LDL cholesterol levels (1 study, 40 people: MD -1.00 mmol/L, 95% CI -1.56 to -0.44).

Authors' conclusions: Dietary interventions have uncertain effects on mortality, cardiovascular events and ESKD among people with CKD as these outcomes were rarely measured or reported. Dietary interventions may increase health-related quality of life, eGFR, and serum albumin, and lower blood pressure and serum cholesterol levels.Based on stakeholder prioritisation of dietary research in the setting of CKD and preliminary evidence of beneficial effects on risks factors for clinical outcomes, large-scale pragmatic RCTs to test the effects of dietary interventions on patient outcomes are required.

Conflict of interest statement

1. Suetonia C Palmer: none known

2. Jasjot Maggo: none known

3. Allison Tong: none known

4. Katrina L Campbell: none known

5. Jonathan C Craig: none known

6. David W Johnson: none known

7. Bernadet Sutanto: none known

8. Marinella Ruospo: none known

9. Giovanni FM Strippoli: none known

Figures

1

Flow diagram of study selection

2

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

3

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

References

References to studies included in this review Campbell 2008 {published data only}

Chanwikrai 2012 {published data only} DIRECT Study 2013 {published data only} Facchini 2003 {published data only} Flesher 2011 {published data only} Goraya 2013 {published data only} Goraya 2014 {published data only} Leon 2006 {published data only} Mekki 2010 {published data only} Orazio 2011 {published data only} Riccio 2014 {published data only} Stachowska 2005 {published data only} Sutton 2007 {published data only} Teng 2013 {published data only} Tzvetanov 2014 {published data only} Whittier 1985 {published data only} Zhou 2011b {published data only} References to studies excluded from this review Parillo 1988 {published data only} References to ongoing studies INTENT Study 2014 {published data only} Additional references Abiemo 2012 Adler 2014 Anderson 2008 Chadban 2003 Chen 2016 Estruch 2013 Fouque 2009 Go 2004 GRADE 2008 Gutierrez 2014 Hartley 2013 Hemmelgarn 2010 Higgins 2003 Higgins 2011 Hoffmann 2014 Jha 2013 Johnson 2011 Jun 2012 KDIGO 2012 Liu 2015 Manns 2014 McMahon 2015 Moore 2014 Muntner 2013 Nakayama 1996 Nettleton 2008 Nield 2008 Orozco 2008 Palmer 2015a Peters 2000 Rees 2013a Rees 2013b Robertson 2007 Schunemann 2011a Schunemann 2011b Singh 2009 Stamler 1996 Tong 2015 Tong 2015a Tong 2015b van Dijk 2012 Weiner 2006 Wyld 2012 Zamora‐Ros 2013 Zhang 2012 References to other published versions of this review Palmer 2015b