EAL

HESI: Congestive Heart Failure Population (2014)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare differences in cardiac event-free survival between patients with sodium intake above and below 3g.

Inclusion Criteria:

Confirmed diagnosis of chronic HF with either reduced left ventricular ejection faction (LVEF) less than 40% or preserved LVEF of 40% or more
On stable doses of medications for at least three months
Able to read and speak English.

Exclusion Criteria:

Referred for heart transplantation
History of acute myocardial infarction or cerebrovascular accident within the prior three months
Valvular heart disease, peripartum HF or myocarditis as primary HF etiology
Other known inflammatory processes
Endstage renal failure
Co-existing terminal illness such as cancer.

Description of Study Protocol:

Recruitment
This was a prospective observational study of patients with HF recruited from outpatient clinics associated with six large community hospitals or academic medical centers in Kentucky, Georgia, Indiana and Ohio.

Design

Prospective cohort.

Intervention

Trained research assistants explained the purposes and procedures for the study and written informed consent was obtained
Patients were visited in their home to be provided with urine collection equipment and given detailed written and verbal instructions for the 24-hour collection procedure
Subjects were instructed to continue their normal eating and drinking habits. No patients were placed on fluid restriction by their health care provider during the study period.
To insure accurate and complete urine collection, a research assistant called patients the morning urine collection began to review the procedure and remind them of start and end times for urine collection
Patients recorded volume and time of each void in a log
The logs and urine container were brought by patients to the GCRC the morning of 24-hour urine collection completion
Research nurses verified data on clinical variables and completeness of 24-hour urine collection. Patients were followed by telephone interview every month for 12 months to collect event-free survival data.

Statistical Analysis

Differences in cardiac event-free survival were determined by the Kaplan-Meier survival curve with log rank test and Cox hazard regression. Data analyses were performed using SPSS for Windows 16.0.
Descriptive statistics, including frequencies with percents and means with standard deviations, were used to describe patient characteristics. For the purpose of using UNa as an estimate of dietary sodium intake, UNa in mmol was converted to mg (mg = mmol Å~ 22.99).
Patients were stratified into NYHA Class I/II and III/IV and grouped within each stratum using a 3g 24-hour UNa cut point. Differences in event-free survival between groups within each stratum was tested using a Cox proportional hazards model while controlling for age, gender, HF etiology, BMI, LVEF and total comorbidity score. A hazard ratio (HR) for event-free survival was obtained for all independent variables, along with 95% CIs.

Data Collection Summary:

Timing of Measurements

Baseline for dietary sodium intake and 24-hour urine data collection
Called monthly for 12 months to event-free survival information.

Dependent Variables

A 24-hour UNa as an indicator of dietary sodium intake
A 24-hour UNa and event-free survival.

Independent Variables
Level of sodium intake.
Control Variables

Age
Gender
Etiology of HF
NYHA functional class
Left ventricular ejection fraction (LVEF)
Prescribed medications
Total comorbidity score using Charlson’s comorbidity index.

Description of Actual Data Sample:

Initial N: A total of 349 patients were eligible for this study. One patient declined to participate, seven patients withdrew, three patients were lost to follow-up and 36 had incomplete 24-hour urines based on urine collection logs or UNa values below 40mEq per L per day.
Attrition (final N): N=302 patients (203 males, 99 females)
Age: The majority were over 65 years (range 23 to 97 years), with mean age at 62±12 years
Anthropometrics: More than 50% were obese
Location: Clinics in Kentucky, Georgia, Indiana and Ohio.

Summary of Results:

Findings

Higher UNa excretion levels (3,000mg per day or more) significantly associated with longer event-free survival
NYHA class I/II: HR=0.44; CI: 0.20, 0.97; P=0.040
NYHA class III/IV: HR=2.54; CI: 1.10, 5.83; P=0.028.

Author Conclusion:

The authors suggest that 3g dietary sodium restriction may be most appropriate for patients in NYHA functional classes III and IV.

Funding Source:

University/Hospital:

This study was supported in part by a grant from NIH NINR R01 NR 009280, General Clinical Research Centers at University of Kentucky: M01RR02602, Emory University: M01RR0039, and Indiana University: MO1 RR000750 and by NIH, NINR Center grant 1P20NR010679 to the University of Kentucky College of Nurs

Reviewer Comments:

Limitations noted:

Patients with HF have altered hormonal responses that can lead to fluid and sodium retention. This may make UNa an unreliable indictor of dietary sodium intake.
For subjects, a 24-hour urine was measured one time. Therefore, this single 24-hour urinary sodium excretion may not reflect long-term sodium intake.

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)	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?	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?	N/A
	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?	N/A
	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?		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?	N/A
	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?	N/A
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	No
	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?	N/A
	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?		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