EAL

DF: Cardiovascular Disease (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To study the effectiveness within a free-living population of a low-fat, low-cholesterol diet and oat bran supplementation in either an unprocessed or ready-to-eat form, when consumed separately and in combination.

Inclusion Criteria:

Free-living males and females having at least two consecutive serum cholesterol readings higher than 75th percentile within the past six months
Age 20 to 65 years
Informed consent
Not receiving formal counseling on cholesterol-lowering diet.

Exclusion Criteria:

Pregnant or lactating
Hypothyroidism
Morbid obesity (more than 200% ideal body weight)
Diabetes
Lipid-altering medications
Hospitalized in the past three months.

Description of Study Protocol:

Design

Randomized trial, subjects randomized on group basis.

Intervention

Randomized to one of four treatment groups for 12 weeks:
- 1) Low-fat, low-cholesterol (LFLC): NCEP Step I diet (less than 300mg cholesterol, 30% kcal)
- 2) Low-fat, low-cholesterol and 50g per day unprocessed oat bran (LFLC+OB)
- 3) 50g per day unprocessed oat bran supplement (OB)
- 4) 42.5g per day processed oat bran cereal supplement, RTE B-glucan (POB)
Supplement provided as ready-to-eat cereal. Subjects met with dietitian to discuss LFLC diet and incorporating supplement into diet. Subjects were followed every four weeks.

Statistical Analysis

ANOVA (with repeated measures to look over time and between groups)
Chi-square analyses
P<0.05.

Data Collection Summary:

Timing of Measurements

Prior to study: Two-week diet record (weight, height, total cholesterol, HDL-cholesterol)
Meeting with RD for diet counseling in each condition (recipes, diet modification); administer and collect unused supplements as needed
Follow-up visits at four-week intervals for 12 weeks (for weight, cholesterol, diet records).

Dependent Variables

Total cholesterol (enzymatic Allain procedure)
HDL-cholesterol (Seralyzer reflectance photometer)
Dietary data (three-day food records, Group Diet Calculation Program).

Independent Variables

Quantity and type of fiber.

Control Variables

Gender
Hypertension
TC
HDL-cholesterol
TC:HDL-cholesterol
BMI.

Description of Actual Data Sample:

Initial N: N=81
Attrition (final N): N=15 in LFLC, 18 in LFLC+OB, 15 in OB, 20 in POB
Location: Syracuse, NY, US.

Summary of Results:

Key Findings

Variables	LFLC	LFLC+OB	OB	POB	Statistical Significance of Group Difference
Serum cholesterol change over time (%)	-17.1	-13.1	-12.3	-10.1	NS between groups, all significant over time.
Total-C: HDL-C pre- ; post-	6.6±0.34; 5.7±0.28	6.9±0.45; 6.6±0.92	7.0±0.40; 6.5±0.30	6.4±0.29; 5.7±0.22	NS between groups, all significant over time.

Other Findings

All of the diet therapies were statistically and practically significant in reducing calculated risk for CVD
Reduction in mean body weight ranged from 0% to 5%; LFLC+OB losing most (4.2% to 4.9%); POB the least (0% to 0.1%). NS differences between groups.
Impact of diet on dietary intake:intake of many nutrients changed significance over time in all groups: EI decreased; CHO, protein, fat decreased; saturated fat decreased.

Author Conclusion:

Both the low-fat, low-cholesterol (LFLC) diet and the oat bran (OB) supplementation were found to reduce serum cholesterol levels.

Funding Source:

Reviewer Comments:

Very small sample size
Compliance not reported.

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?	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.)	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?	No
	6.6.	Were extra or unplanned treatments described?	No
	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)?	Yes
	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?	No
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