EAL

CKD: MNT (2010)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The purpose of this study was to determine if nutrition counseling can decrease dietary protein intake and to identify predictors of adherence in patients with type 2 diabetes mellitus and microalbuminuria in The Netherlands.

Inclusion Criteria:

Type 2 diabetes mellitus
in primary care
<79 years of age
microalbuminuria: 30-300 mg/ 24-hr (mean of 2 samples), or >20 mg albuminuria/24-hr in at least 2 samples, or urinary albumin >6.5 mg/L in 2 samples, or duration of diabetes >5 yr.
protein intake >0.8 g/kg/d based on urine urea excretion
During a pretrial qualification period, subjects received 2 45-minute sessions of nutrition counseling with a dietitian regarding a restricted saturated fat diet; subjects also completed a FFQ and were able and willing to understand the diet information and not reluctant to change their diet, as assessed by the dietitian.

Exclusion Criteria:

recovering from severe morbidity
protein-losing enteropathy
venous leg ulcer
pressure ulcer
presence of malignancy
psychiatric or serious psychosocial problems

Description of Study Protocol:

Recruitment: described elsewhere

Design: 2-part study.

Subjects were randomized to either experimental (0.8 g protein/kg/d) or control (usual) groups, following a pre-trial qualification period.
Those in the experimental arm were subdivided into 2 groups, based on changes observed during the qualification period:
- those who decreased protein intake by >5 g/day
- those with a smaller decrease or an increase of daily protein intake

Blinding Used: no

Intervention: Dietitian provided counseling for approximately 30 minutes at 0,1,3,6,9 and 12 months for saturated fat restriction (control group) or saturated fat restriction with goal of decreasing protein intake to 0.8 g/kg/day (experimental group). Counseling based on Health Counselling Model, to identify barriers, involve patients in solutions, and provide feedback. Both groups received the same amount of attention.

Statistical Analysis: p-values indicated if <0.20. Linear regression analysis used to estimate the overall effect of diet counseling on protein intake and to assess predictors of adherence on a continuous scale. Two sided t-tests or chi-squared tests used to predict degree of adherence to protein restriction. Wilcoxon tests used when variable not normally distributed. Associations between adherence and predictors examined using partial Pearson correlation (simple model) and multiple regression model. Adjustments influenced by regresion to the mean using Blomqvist method. SPSS, version 5.02.

Data Collection Summary:

Timing of Measurements:

Protein intake, estimated from 2 x 24 hour urine samples for urinary urea excretion at baseline, 6 and 12 months; in the experimental group, also assessed from single 24 hour samples at 3 and 9 months.
FFQ apparently administered for baseline, 6 and 12 month measures.
Diet satisfaction measured at baseline and at 12 months by completing a visual analogue after each meal for 3 days.
Questionnaire to determine barriers for changing diet was completed once (prior to 3-month consultation) during the study.

Dependent Variable:

Mean change in dietary protein intake according to urinary urea excretion.

Independent Variables:

Demographic: gender, age, education, living alone
Medical: HbA1C, self-rated health, smoking, body weight, BMI, hypertension
Diet-related: intake of protein, saturated fat, energy, and alcohol

Control Variables: NA

Description of Actual Data Sample:

Initial N: the randomized trial included 160 participants: 81 experimental, 79 control.

Attrition (Final N): 59 experimental and 66 control subjects completed 12 months of follow up (78%). Attrition mainly from comorbidities or logistical problems, rarely due to diet.

Age: < 79 years

Ethnicity: not mentioned

Other Relevant Demographics:

Anthropometrics:

Location: The Netherlands

Summary of Results:

1. Based on urinary urea excretion to calculate protein intake, the experimental group was compared to the control group. A significant difference between mean change in protein intake was noted at 6 months, but this difference was not sustained at the 12 month follow up.

**Mean changes in protein intake **(g/day)** according to urinary urea excretion**
Months	Experimental (n=59)	Control (n=66)	Difference (change E - change C)
0	93+19	93+20
3-0	-3.2+20	NA
6-0	-3.3+15	+4.4+17	-7.6+2.7*
12-0	-2.8+18	+1.1+17	-3.9+3.1
* p=0.006

2. Characteristics were compared at baseline between the 2 subgroups of the experimental subjects. Small significant differences (p<0.20) were noted for the following:

	decrease > 5 g/d protein (n=28)	< 5 g/d protein decrease (n=31)	p-value
Living alone (%)	21	10	0.15
Self-rated health (% very healthy)	62	39	0.10
Cigarette pack years	23	5	0.13
Nondrinker (%)	32	52	0.13
FFQ:
Protein, g	100+18	86+17	0.004
Saturated fat, g	24.1+9	28.3+12	0.14

3. Some nonsignificant characteristics at baseline for these subjects include:

decrease > 5 g/d protein

< 5 g/d protein decrease

Age, yr

65+10

64+7

A1C, %

7.7+1.4

7.6+1.3

BMI

27.3+3.8

27.3+4.4

4. Three variables met the criteria for prediction (r>0.20 and p<0.20): baseline BMI, baseline diet satisfaction, and living alone (vs with partner). Using a multiple model analysis, the variation explained by the 3 variables was 11%. The predictive value of (lower) BMI must be interpreted with caution based on outlier data for this variable.

Author Conclusion:

The study population, compared to type 2 diabetics in general, should be considered rather motivated, based on pretrial selection criteria. Authors attribute low adherence to the protein restriction based on participants feeling healthy, not feeling threatened by renal disease, and having a low perception of the importance of compliance.

Diet counseling resulted in a very moderate degree of protein restriction.

Patients who were well satisfied with their pre-existing diet showed good adherence, as did those living alone, and those less overweight.

Current smokers tended to adhere well to the diet.

No relationship was found with age, blood pressure, use of antihypertensive prescription medicine, level of education, or number of reported patient barriers.

Knowledge about these predictors offer health professionals at least some opportunity to choose to address their counseling mainly to those who are more amenable or to those who would require additional efforts to achieve dietary change.

Funding Source:

University/Hospital:

Vrije Universiteit, University of Maastricht

Reviewer Comments:

Impressive statistical analyses and useful discussion of results.

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?	No
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)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	Yes
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	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?	N/A
	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?	Yes
	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?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	No
	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.)	No
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	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?	Yes
	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?	N/A
	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?	Yes
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