EAL

HESI: Congestive Heart Failure Population (2014)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine whether adherence to a sodium-restricted diet (SRD; less than three grams per day) is associated with lower symptom burden
To determine whether adherence to a SRD independently predicts cardiac event-free survival among heart failure patients.

Inclusion Criteria:

Confirmed diagnosis of chronic heart failure (review of medical records, according to Framingham criteria)
Diagnosed with heart failure for at least two years
Having non-preserved left ventricular systolic function with LVEF under 40%
Prescriptions for stable doses of heart failure medications for at least three months prior to the start of the study.

Exclusion Criteria:

No acute myocardial infarction or cerebrovascular attack within the previous six months
No obvious cognitive impairment (stroke, dementia, head trauma)
No history of cancer, severe thyroid disease, liver or renal failure.

Description of Study Protocol:

Recruitment: Subjects were recruited from several outpatient heart failure clinics at two large university hospitals
Design: Prospective cohort study. At each clinic, patients received instruction on how to follow SRD and how to monitor daily symptoms. Patients then followed for 12 months.
Intervention: Sodium-restricted diet, less than three grams of sodium per day.

Statistical Analysis

Independent T-test to compare those with urinary sodium above and below three grams
Hierarchical multiple linear regression to determine associations between non-adherence and greater symptom burden
Hierarchical Cox proportional hazards regression and survival curves to determine whether non-adherence to SRD predicted cardiac event-free survival in heart failure patients after controlling for risk factors.

Data Collection Summary:

Timing of Measurements

Timing of 24-hour urine collection not described
Monthly phone interviews to assess cardiac event status.

Dependent Variables

Adherence to SRD: 24-hour urinary sodium excretion
Symptom burden: Modified Memorial Symptom Assessment Scale-Heart Failure (MSAS-HF)
Cardiac event-free survival: Composite end-point of time to first event of cardiac-related hospitalization or death due to cardiac events during the 12-month follow-up period.

Independent Variables

SRD (under three grams of sodium per day).

Control Variables

Age
Gender
Cause of heart failure
BMI
NYHA functional class
LVEF
Total comorbidity scores.

Description of Actual Data Sample:

Initial N: 271 eligible; 11 declined, four withdrew, 18 did not complete 24-hour urine collection, two were lost to follow-up
Attrition (final N): 232 (165 male, 67 female)
Age: 65±10 years
Ethnicity: Asian.

Anthropometrics

BMI: 24.2±4.0kg/m² (23.2% obese, 34.1% overweight)
Location: Seoul, South Korea.

Summary of Results:

Key Findings

Average 24-hour urinary sodium was 3,827±1,436mg per day
- Fewer than 20% of patients had a 24-hour urinary sodium measurement indicating a daily sodium intake of less than two grams
- 35% had 24-hour urinary sodium of three grams per day or less
- Those with 24-hour urinary sodium over three grams per day had higher BMIs than those with less (P<0.01).
24-hour urinary sodium over three grams per day was independently associated with greater symptom burden (P=0.007) after adjusting for age, gender, heart failure cause, BMI, LVEF, total comorbidity score and NYHA functional class
Patients with 24-hour urinary sodium over three grams per day had shorter cardiac event-free survival compared to those below three grams per day (P=0.008), having a 1.8-times higher risk for cardiac events.

Author Conclusion:

Patients who did not adhere to the SRD of less than three grams of sodium per day had greater symptom burden and were two times as likely to experience cardiac events during a 12-mont follow-up period.

Funding Source:

Other:

not described.

Reviewer Comments:

Methods of urinary sodium measurement not described (timing, baseline measurement)
Not corrected for creatinine.

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?	Yes
	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")?	Yes
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?		N/A
	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?	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?	???
	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?	No
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?	Yes
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?	No
	10.2.	Was the study free from apparent conflict of interest?	Yes