EAL

CKD: Dietary Protein (2001)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The purpose of this study was to evaluate the influence of Supplemental Very Low Protein Diet (SVLPD) on the clinical outcome and nutritional status of patients with advanced chronic renal failure during the predialysis period and their evolution after initiation of dialysis and/or transplantation.

Inclusion Criteria:

Adult patients followed by the Nephrology Service of Hospital Pellegrin, Bordeaux, France.
Advanced chronic renal failure with a GFR <25 ml/min/1.73 m2

Exclusion Criteria:

Initiation of dialysis
Excessively severe comorbid conditions
Incapable of following vegetarian diet and its monitoring

Description of Study Protocol:

Recruitment

Consecutive patients with advanced chronic renal failure (GFR <25 ml/min per 1.73 m²) were selected from the Service de Nephrologie, Hopital Pellegrin, Bordeaux, France

Design

Patients with advanced chronic renal failure who were prescribed a SVLPD were followed until they started dialysis, which was considered as T_end

Blinding used (if applicable): not applicable

Intervention (if applicable)

Supplemented very low protein diet providing 0.3g protein, 35kcal/kg, and 5 to 7mg of inorganic phosphorus per kg per day administered for a mean duration of 29.6 +/- 25.1 months.

Statistical Analysis

ANOVA and the Fischer exact test were used for comparisons between groups. t-test were used for same patient comparisons between two periods.

Data Collection Summary:

Timing of Measurements

The patient and the patient's family were introduced to the dietary prescription by a specifically trained dietitian familiar with the theoretical and practical aspects of SVLPD in patients with CRF. Patients were evaluated every month as outpatients.

Dependent Variable

BMI
Serum albumin
Mortality

Independent Variables:

Diet compliance was assessed by food diaries and 24-hr urinary urea nitrogen excretion.
Physical examination was performed
A joint dietitian and physician visit was conducted and diet prescription adjustments were made if necessary.

Control Variables:

Description of Actual Data Sample:

**Initial N:** 293 subjects

**Attrition (final N):** 292 subjects, two subjects were lost to follow-up

**Age:** Ranged from 14 to 87 with a mean age of 50.2 +/- 15.6

**Ethnicity:** not mentioned

**Other relevant demographics and Anthropometrics:**
Subject Characteristics at Baseline
	Mean+SD
Age, yr	50.2+15.6
Weight, kg Males	69.4+10.3
Weight, kg Females	56.2+9.9
BMI	22.3+3.3
Plasma creainine, µmol/L	437+120
Serum albumin, g/L	38.4+5.3
Plasma bicarbonate, mmol/L	22.6+3.7
Serum PTH, pg/ml	213+168
GFR, ml/min	13.1+4.8
Protein intake, g/kg	0.85+0.23
Proteinuria, g/d	2+2.3

The primary causes of CKD were glomerulonephritis (23%), interstitial nephritis (21%), polycystic kidney disease (15%), and chronic rejection (12%). Diabetes represented only 7.4% and nephrosclerosis, 10%.

Location: France

Summary of Results:

Characteristics of 165 dialysis patients who participated in the SVLPD:
	Baseline	End
Age, yr	50.1+15.8	52.6+16.1
Weight, kg	64.2+12.1	64.6+12.1
BMI	22.4+3.3	22.5+3.4
Protein intake (g/kg/d)	0.86+0.22	0.48+0.13*
Plasma Creatinine (µmol/L)	458+123	748+183*
Bicarbonate (mmol/L)	22.4+3.6	24.1+2.9*
Serum albumin (g/L)	38.7+4.4	38.8+4.8
GFR, ml/min+	13.1+4.8	5.8+1.5*
PTH, pg/ml	211+49	206+198
Urinary protein (g/d)	1.9+1.9	1.5+1.4
Follow-up, months		29.8+23.1

+ available in 93 subjects

*P<0.0001, baseline vs. end of SVLPD

Nutritional status (serum albumin and weight) was stable during the SVLPD and bicarbonate levels increased into the normal range.

20 patients (8.3%) discontinued the study and 14 subjects (5.9%) died primarily from CVD or cancer, 69% started chronic dialysis and 5% received transplants.

The mean duration of dialysis was 54 months; the mortality rate after initiation of dialysis was 2.4%, 25%, and 50% after 1, 5 and 10 years, respectively.

Author Conclusion:

SVLPD can be safely used in patients with CKD without adverse effects on the clinical and nutritional status of the patients. Due to the preservation of nutritional status and the correction of uremic symptoms, the initiation of dialysis was deferred in these patients. The outcome of patients on RRT was not affected by prior treatment with SVLPD during the predialysis phase of CKD.

Funding Source:

University/Hospital:

Service de Ne´phrologie Hoˆpital Pellegrin, Centre de Traitement des Maladies Re´nales Saint-Augustin, Service de Ne´phrologie, Hoˆpital Saint-Andre, Association pour l’Usage du Rein Artificiel a` Domicile en Aquitaine (France)

Reviewer Comments:

The estimated protein intake with amino acid supplementation was estimated to be ~50 g/d.

The subjects were seen by the dietitian and physician together every month throughout the study. No report of the actual time per encounter was reported in this study.

Compliance to the diet was high as determined by monthly urinary urea nitrogen and diet records. Subjects were required to demonstrate willingness to follow the diet during a 3-month trial period. Therefore, the subjects in this study were more motivated than the general population with CKD.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		Yes
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	Yes
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	Yes
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	6.6.	Were extra or unplanned treatments described?	Yes
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	N/A
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	Yes
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes