EAL

HF: Effectiveness of RD-delivered MNT in Patients with Heart Failure (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the effects of a dietary intervention focused on the improvement of clinical and nutrition status and quality of life and relief from symptoms.

Inclusion Criteria:

Age 18 and older
HF, as diagnosed by echocardiogram and defined as decreased systolic or diastolic function.

Exclusion Criteria:

On a specific dietary regimen
Renal failure
Uncontrolled dysthyrodism
Hepatic failure
Unstable ischemic heart disease (unstable angina or myocardial infarction)
Myocardial revascularization procedures within previous three months
Severe arrhythmias.

Description of Study Protocol:

Recruitment: Patients attending the Heart Failure Clinic of the National Institute of Medical Science and Nutrition in Mexico City
Design: RCT
Blinding used: Cardiologists were blinded when evaluating echocardiograms and clinical symptoms.

Intervention

A 2.0g to 2.4g sodium diet, with 50% to 55% carbohydrate (complex carbs and fiber emphasized), 15% protein, 30% to 35% fat (under 10% saturated, 10% polyunsaturated, 15% monounsaturated and more than 300mg cholesterol) with total fluids limited to 1.5L per day (including water in food), was prescribed to the intervention group
The diet was given to the patients in both written and oral instructions by a dietitian, who advised them to avoid sodium-rich food, limit the intake of food with moderate amounts of sodium and to eat no more than 0.25 teaspoons of salt per day
The control group received traditional management of HF including common dietary advisories regarding decreased sodium and fluid intakes.

Statistical Analysis

All analyses were performed with commercially available software (SPSS)
Continuous variables are expressed as mean ± standard deviation and categorical variables are presented as absolute and relative frequencies
Unpaired T-tests were used to compare the two groups at baseline and to compare changes from baseline to six months (end of study) between groups, if the variables were continuous
To compare the changes from baseline to six months between groups to categorical vaiables, McNemar's Test was used for dichotomy variables and Friedman's Tests were used for variables of more than two categories
P<0.05 was considered statistically significant.

Data Collection Summary:

Timing of Measurements: Baseline and six months, except for an additional 24-hour food recall at three months.

Dependent Variables

Body composition was performed by measuring height, weight and body fat
- Height and weight were performed barefoot and in little clothing
- Body fat was determined by tetrapolar and multiple-frequencies (BodyStat QuadScan 4000).
Daily physical activity was evaluated by a three-day questionnaire, using the average of two week days and one weekend day
Dietary intake and physical activity were obtained by a three-day food record. The nutrients were an average of the three days analyzed, using the software SCVAN 1.0, which includes the values for Mexican food.
Fasting blood samples were analyzed for plasma concentrations of glucose, albumin, hemoglobin, hematocrit, triacylglycerol (TG), total cholesterol (TC), high-density lipoprotien cholesterol (HDL) and low-density lipoprotein cholesterol (LDL)
- Plasma glulcose was enzymatically determined with the glucose oxidase technique and plasma concentration of TC and TG were measured with an automated system (Synchron CX5)
- HDL was precipitated with phosphotungstic acid and Mg²⁺ and LDL was calculated as follows: TC-(HDL+TG/5)
- Dyslipidemia was defined as a TC above 200mg per dL, LDL above 100mg per dL, HDL above 40mg per dL (printed this way in the text) or a TG over 150mg per dL.
24-hour urines were assessed for sodium excretion: To evaluate sodium intake, it was assumed that 24-hour urinary sodium excretion is equivalent to approximately 86% of the daily sodium intake
Symptoms of fatigue, dyspnea, edema, congestion (dyspnea, edema, weight gain, decubitus intolerance and effortful coughing) and functional class, according to the New York Heart Association (NYHA), were evaluated during the medical interview. A baseline echocardiogram was performed at baseline to determine cardiac function. All evaluations were performed by a cardiologist blinded to the study groups.
Quality of life was determined by a questionnaire adapted from the Kansas City Cardiomyopathy Questionnaire and the Minnesota Living with Heart Failure Questionnaire
- It identified physical limiations, social interference, symptoms, food intake, emotional and economic aspects, sleep disturbances, medication side effects and comprehension of medical indications; overall quality of life was the sum of these
- For the test-retest reliability of this instrument, a K-value higher than 7.0 (P<0.05) was obtained for each item. To facilitate interpretability, the score for each domain was transformed to a 0-to-100 range by subtracting the lowest possible score, dividing by the range of the scale and multiplying by 100. Thus, results near 100 would indicate better quality of life.

Independent Variables

2.0g to 2.4g sodium diet with 50% to 55% carbohydrate (complex carbs and fiber emphasized), 15% protein, 30% to 35% fat (over 10% saturated, 10% polyunsaturated, 15% monounsaturated and over 300mg cholesterol), with total fluids limited to 1.5L per day (including water in food), was prescribed to the intervention group
The control group received traditional management of HF, including common dietary advisories regarding decreased sodium and fluid intakes.

Description of Actual Data Sample:

Initial N: 65 (unknown division of males and females)
Attrition (final N): 58 (21 males, 37 females); three were excluded from the intervention group, due to non-adherence to the diet. In the control, one patient was exluded from the clinic and three were lost to follow-up
Age: 64.2±16.2 (intervention) and 59.5±16.4 (controls)
Ethnicity: Not described.

Anthropometrics

There was a statistical difference in gender between groups
There were no significant difference at baseline in symptoms, comorbidities and diuretic use
Both groups had the the same degree of of compromise in functional capacity
There was a high prevalence of dyslipidemia, hypertension and ischemic heart disease in both groups
Mean nutrient intake was also similar.

Location

Mexico City (National Institute of Medical Science and Nutrition "Salvador Zubiran").

Summary of Results:

Variables	Treatment Group Measures and Confidence Intervals (Percentage Change)	Control Group Measures and Confidence Intervals (Percentage Change)	Statistical Significance of Group Difference P-value
Energy (kcal)	-16.8±24.7	10.7±30.6	0.001
Carbohydrate (g)	-9.7±31.4	10.0±30.7	0.02
Protein (kcal Percentage)	10.9±27.0	-2.2±18.2	<0.05
Total Fat (g)	-26.4±32.9	16.2±40.6	<0.0001
Fat (kcal Percentage)	-13.3±25.1	4.4±19.6	0.01
Saturated Fat (g)	-43.0±42.1	35.4±65.1	<0.0001
Saturated Fat (kcal Percentage)	-36.6±31.2	28.3±70.0	<0.0001
Sodium (mg)*	-50.5±34.9	48.1±164.7	0.012
Total Fluids	-4.1±36.9	25.2±44.4	0.01
Emotional Aspects	98.3±193.2	13.8±48.2	0.03
Sleep Disturbance	39.5±108.9	-5.1±35.9	0.05
Total Quality of Life	19.3±31.7	3.2±18.4	0.02
Physical Activity	2.5±7.4	-3.1±12.0	<0.05

*Excluding salt for cooking

Variables	Treatment Group Measures and Confidence Intervals	Control Group Measures and Confidence Intervals	Statistical Significance of Group Difference (P-value)
24-Hour Sodium Excretion (mg)	1,942.7±566.7	2,535.2±1,012.3	<0.05

Other Findings

There were no significant changes in any of the anthropometric variables (BMI, weight, body composition of fat and lean mass, water and dry weight), except for decreased extracellular water in the intervention group; -1.1% vs. 1.4% (control), P=0.03
In the intervention group, frequency of signs and symptoms of HF decreased in the intervention group: Edema changed from 37% to 7.4%, P=.008; fatigue changed from 59.3% to 25.9%, P=0.012. There were no significant changes in the control group.
Uses and doses of diuretics were similar at baseline and at the end of the study in both groups
The intervention group had a significant number of patients (P=0.025) with improvement in functional class, while the control group had improvements, but they were not statistically significant
There were no significant differences in the results when the two groups were stratified by sex, according to a general lineal model.

Author Conclusion:

An isocaloric dietary intervention with restrictions of sodium, saturated fats, sugars and fluids has favorable effects on the clinical state, NYHA functional class and quality of life in patients with HF
Moreover, a restriction of sodium intake to less than 2,400mg per day and of total fluids to less than 1,500ml per day had a positive effect by decreasing the amount of extracellular fluid and hence the development of edema, elevating functional class and enhancing quality of life by permitting engagement in ordinary activities that help integrate patients into their social environments, with the positive emotional effect that this implies.

Funding Source:

Government:

Instituto Nacional de Ciencias Medicas y Nutricion

Reviewer Comments:

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)	???
	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?	No
	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?	???
	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.)	Yes
	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?	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?	N/A
	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?	N/A
	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?		No
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	No
10.	Is bias due to study's funding or sponsorship unlikely?		???
	10.1.	Were sources of funding and investigators' affiliations described?	No
	10.2.	Was the study free from apparent conflict of interest?	???