DF: Cardiovascular Disease (2008)
To examine the plasma lipoprotein/lipid response to oat bran-rich supplement giving during four weeks in overweight pre-menopausal women.
- Normal cycling pre-menopausal overweight women
- BMI of 25kg/m2 and above
- Aged from 18 years to 53 years.
- Irregular menstrual cycle; pregnancy; lactation; plans for pregnancy; use of oral contraceptives; use of medications affecting plasma steroid and lipid levels such as thyroid hormones, antihypertensive and antidiabetic medications, lipid-lowering agents, etc; chronic diseases requiring medication
- Excluded from the analyses: Anemia, irregular menstrual cycle or abnormal thyroid (11); irritable bowel syndrome (one); personal reasons (eight); time concerns (three).
Recruitment
Women were recruited from the greater Quebec City through newspapers and advertising on the Laval University campus.
Design
- Randomized controlled clinical trial
- All subjects had a run-in period for two weeks, in which they followed the National Cholesterol Education Program Step I diet. After this phase, subjects were randomly assigned to the Control Group without supplement or to the Treatment Group, which consumed oat-bran enriched muffin during four weeks.
- Both groups followed the NCEP Step I diet during the treatment period. Muffins were prepared at home following instructions given by the researchers. Compliance was measured by asking the subjects to record muffin intake. Three-day food records were completed by each participant before the beginning of the study and at the end of each study phase. A questionnaire about possible secondary effects were completed during each phase. Physical activity was evaluated at baseline, two and six weeks.
Blinding Used
Not mentioned: Lab tests.
Intervention
- Group Treatment: 28g per day of oat-bran enriched muffin (two per day)
- Group Control: Two muffins per day without oat-bran.
Statistical Analysis
- Paired Student's T-test to evaluate changes in metabolic variables
- When differences between Control and Treatment Groups were assessed, Student's T-test was used
- ANOVA was used to adjust for covariates
- X2 analyses used to explore the differences in the secondary effects between Control and Treatment Groups.
- Statistical difference was considered when P≤0.05.
Timing of Measurements
- Plasma lipids and anthropometric parameters were measured at baseline and at two and six weeks
- Dietary intake was measured in the beginning and end of study (baseline and six weeks).
Dependent Variables
- Total cholesterol, triglyceride and HDL-cholesterol: Enzymatic assays
- LDL-cholesterol: Calculated with the Friedewald formula
- Apoprotein B: Immunoelectrophoretic method of Laurell
- Apoprotein E
- Waist circumference: Airlie conference standards
- Weight (kg) and BMI.
Independent Variables
Oat-Bran Treatment Group vs. Control Non-Fiber treatment.
Control Variables
- Age
- Apo-E genotype
- Weight change.
- Initial N: 57 F
- Attrition (final N): 34 females; 16 in the Control Group and 18 in the Treatment Group
- Age: Mean, 37.4 (Control Group) and 39.1 (Treatment Group)
- Ethnicity: Not mentioned
- Other relevant demographics: There was a tendency for HDL-cholesterol be higher in the Treatment Group, when compared with Control; 1.50±0.32mmol per L and 1.37±0.23mmol per L, respectively
- Antropometrics: There was a tendency for higher BMI, weight and waist circumference in the Control Group. One woman with a BMI of 23.6 was included in the study.
- Location: Laval Universtiy; Quebec, Canada.
Variables | Treatment Group | Control Group | ||||
Week 2 | Week 6 | Statistical Difference | Week 2 | Week 6 | Statistical Difference | |
Total Cholesterol, mmol/L |
4.55±0.76
|
4.67±0.89
|
NNSS |
4.60±0.88
|
4.63±0.93
|
NS |
LDL-C, mmol/L |
2.69±0.71
|
2.69±0.92
|
NS |
2.71±0.76
|
2.73±0.83
|
NS |
HDL-C, mmol/L |
1.35±0.30
|
1.49±0.32
|
P<0.001; P<0.05* |
1.28±0.26
|
1.30±0.25
|
NS |
Triglyceride, mmol/L |
1.10±0.49
|
1.07±0.49
|
N.S |
1.35±0.73
|
1.32±0.69
|
NS |
Total-C/HDL Ratio |
3.56±1.11
|
3.32±1.08
|
P<0.001 |
3.78±1.13
|
3.71±1.06
|
NS |
LDL-C/HDL-C Ratio |
2.15±0.87
|
1.95±0.89
|
P<0.001 |
2.25±0.86
|
2.21±0.87
|
NS |
BMI |
28.5±4.8
|
28.4±4.8
|
NS |
29.4±3.8
|
29.1±3.8
|
P<0.05 |
Weight, kg |
75.7±12.8
|
75.3±12.8
|
NS |
80.4±12.0
|
79.7±12.2
|
P<0.05 |
Values are means ±SD
*Control Group vs. Treatment Group.
- Results remained similar after adjustment for age, apo E genotype and weight change
- Plasma total cholesterol, LDL and HDL, according to responders and non-responders (nine women from Control and 13 women from Treatment): Among responders, HDL was statistically increased in the Treatment Group (P=0.02), but not the total cholesterol. Although LDL-cholesterol decreased more in the Treatment Group, the difference was not statistically significant.
Other Findings
- Following the run-in period, there was a decrease in energy intake (P=0.01); in fat intake (P<0.001); in the percentage of energy from fat, saturated fat and monounsaturated fat (P<0.001)
- Dietary intake was not changed until the end of the study.
"The results suggest that oat bran-rich foods have a beneficial effect on the metabolic profile of overweight women. Integration of these foods as part of a healthy diet may improve the caridovascular risk profile of women."
- Many statistical tests increases possibility of type 1 error using Paired and Sudent's T-tests to measure the same variables and type 2 error due to the small sample size
- Results are limited for only overweight women without hypercolesterolemia and consuming higher fiber than the general population.
Quality Criteria Checklist: Primary Research
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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? | No | |
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) | No | |
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? | No | |
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? | No | |
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)? | No | |
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 | |