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 low-sodium diet (sodium intake of less than three grams) altered the link between depressive symptoms and event-free survival among patients with heart failure, after controlling for other risk factors.

Inclusion Criteria:

Patients with heart failure confirmed diagnosis with either impaired left ventricular systolic function (LVEF up to 40%) or preserved systolic function (LVEFover 40%)
No acute myocardial infarction within the previous six months
Taking stable doses of heart failure medication for at least three months
No cognitive impairment
No history of cancer, severe thyroid disease, liver or renal failure as defined as serum creatinine level over 2.0mg per dL.

Exclusion Criteria:

Not meeting inclusion criteria.

Description of Study Protocol:

Recruitment: Subjects with heart failure recruited from outpatient heart failure clinics between September 1, 2005 and December 31, 2006
Design: Prospective study
Intervention: Patients asked to follow a low-sodiuma diet (three grams of sodium per day) by clinicians.

Statistical Analysis

Frequencies for categorical variables
Means and SDs for continuous variables
Hierarchical Cox proportional hazards regression models were used to determine whether non-adherence to the low-sodium diet predicted event-free survival in heart failure patients afte controlling for age, gender, cause of heart failure, BMI, etc.
Hazard ratio for re-hospitalization and death was obtained for all independent variables, along with 95% CIs.

Data Collection Summary:

Timing of Measurements

Baseline: 24-hour urinary sodium excretion, blood draw, the Korean version of the Beck Depression Inventory (K-BDI)
Monthly (zero to 12 months): Phone interviews for event-free survival.

Dependent Variables

Adherence to low-sodium diet: Intake less than three grams of sodium per day determined by 24-hour urinary sodium excretion
Event-free survival: Composite end-point of time to first event of cardiac hospitalization or cardiac death during 12-month follow-up period (monthly phone follow-up interviews, review of hospital records, death certificates)
Depressive symptoms (K-BDI).

Independent Variables

Sodium-restricted diet prescription (less than three grams of sodium per day).

Control Variables

Age, gender, cause of heart failure, LVEF, total comormidity index, heigh, weight, BMI, N-termical pro B type natriuretic peptide (NT-pro BNP level).

Description of Actual Data Sample:

Initial N: 295 eligible
Attrition (final N): 254 (145 male, 109 female)
Age: 62±14 years
Ethnicity: Korean
Other relevant demographics: 40.9% with urinary sodium excretion under 3,000mg per day; 59.1% at 3,000mg per day or more
Anthropometrics: 18% obese
Location: Seoul, South Korea.

Summary of Results:

Key Findings

Non-adherence to low-sodium diet independently predicted event-free survival after contolling for other risk factors. Those with 24-hour urinary sodium excretions over 3,000mg had shorter event-free survival than those with excretions below 3,000mg (P=0.028). Patients with depressive symptoms had shorter event-free survival than those without depressive symptoms (P<0.001).

In patients without depressive symptoms, there was a significant difference in the adjusted event-free survival between those above and below the cut-point of three grams for 24-hour urinary sodium excretion (HR, 2.18; 95% CI, 1.16 to 4.08). In patients with a 24-hour urinary sodium excretion below three grams, patients with depressive symptoms had 2.9 times higher risk for cadriac events compared to those without depressive symptoms.

Author Conclusion:

Patients who followed a low-sodium diet had better event-free survival compared to those who did not.

Funding Source:

Government:

NIH, National Institute of Nursing Research

Reviewer Comments:

Timing of measurements not described
Urinary sodium excretion not corrected for creatinine, as described
Intervention not well described.

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?	N/A
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		N/A
	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?		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?		No
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	No
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	???
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	???
	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?	N/A
	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