DF: Cardiovascular Disease (2008)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

Investigate the value of a fiber supplement in the treatment of moderately obese patients.

Inclusion Criteria:
  • Females
  • Ages 18 to 60 years
  • Uncomplicated moderate obesity, at least 120% ideal body weight
  • Gave informed consent.
Exclusion Criteria:
  • Male gender
  • History of gastrointestinal diseases
  • History or signs of alcohol abuse
  • Medication use including diuretics, antacids, H2-blockers, bulk laxatives or other drugs affecting the gastrointestinal tract.
Description of Study Protocol:

Recruitment

Source of subject recruitment not described.

Design

  • Randomized double-blind, parallel controlled trial
  • Two-week run-in period preceded studies.

Blinding Used

  • Double-blind; fiber or placebo tablets appeared identical
  • Patients returned remaining tablets at each visit for counting.

Intervention

Subjects were assigned to either the Fiber Supplement or Placebo Group. Two tablets (either fiber or placebo) were taken with 300ml of water three times daily 20 to 30 minutes before each of the three main meals.

  • Study I
    • 1,400-kcal weight-reducing diet
    • Each subject consumed an additional five grams of dietary fiber (total energy content, 40kcal) daily in six tablets with a mixture of grain and citrus fibers
    • Duration of study: Two months.
  • Study II
    • 1,600-kcal weight-reducing diet
    • Each subject consumed an additional seven grams of dietary fiber (total energy content, 35kcal) daily in six tablets with a mixture of vegetable, grain and citrus fibers
    • Duration of study: Three months.

Statistical Analysis

  • Results given as means with 95% confidence intervals (calculated by Student procedure)
  • One-tailed tests for analyses with statistically signifcant differences set at P≤5%
  • Non-parametric methods with correction for ties used to test differences between and changes within groups
  • Dropouts were participants who discontinued for reasons not related to treatment; last weight before termination recorded
  • Withdrawals were subects were others who did not complete the study; highest weight observed during treatment was recorded.
Data Collection Summary:

Timing of Measurements

  • Baseline: Routine medical examination, body weight, height, blood pressure
  • Control visits each two weeks.

Dependent Variables

  • Weight change
  • Compliance (counted returned tablets)
  • Hunger ratings (visual analog scale, 100mm long with descriptive anchors at either end)
  • Bowel movements (self-evaluation forms and questions at each visit)
  • Blood pressure
  • Side effects.

Independent Variables

Fiber supplement.

Control Variables

  • Dietary evaluation and recall
    • Baseline: Each subject interviewed by nutritionist who conducted 24-hour recall
    • Three additional 24-hour recalls (including a weekend day) per telephone at random days during the two-week run-in period.
  • Dietary advice
    • All patients received verbal and written dietary advice as groups before entering the study
    • Mean daily energy intake calculated to 1,400kcal (Study I) and 1,600kcal (Study II); exchange lists for meal variations were distributed and subjects had training about recommended types of foods.
Description of Actual Data Sample:

Initial N

  • Study I: N=60 (all female)
  • Sudy II: N=45 (all female).

Attrition (final N)

  • Study I: N=54 (all female); 30 to five grams fiber supplement and 24 to placebo
  • Study II: N=41 (all female); 28 to seven grams fiber supplement and 13 to placebo.

Age

Not described.

Ethnicity

Not described.

Anthropometrics

No significant differences in weight between fiber and placebo groups at baseline.

Location

Sweden or Denmark.

Summary of Results:

Variables

Treatment Group
(Measures and Confidence Intervals)

Control Group
(Measures and Confidence Intervals)

Statistical Significance of Group Difference

Weight-Loss, Study I: 5g Fiber for Two Months

Mean (95% CI)
7.0kg (4.7 to 8.2)

Mean (95% CI)
6.0kg (4.7 to 7.4)

P<0.05

Energy Intake, Study I 1,126kcal (1,030 to 1,222) 1,039kcal (956 to 1,122)

P<0.05

Weight Loss, Study II): 7g Fiber for Three Months

6.2kg (4.5 to 7.8)

 4.1kg (1.9 to 6.2)

P<0.05

Other Findings

  • Energy intake in Study I for both fiber and placebo groups was distributed as 47% carbohydrates, 23% protein, 29% fat
  • Hunger ratings trended toward lower hunger feeling in the fiber group over time
  • Few side-effects in both studies; none warranted drug, withdrawals or fiber dose reduction
  • Systolic blood pressure significantly reduced (about 10mmHg) in both groups in Studies I and II (P<0.05)
  • Diastolic blood pressure significantly reduced (about five mmHg) only in the fiber group during Study II (P<0.05).
Author Conclusion:

A comparatively high fiber supplement is of value in treating moderately obese patients.

Funding Source:
Industry:
Farma Food
Commodity Group:
University/Hospital: King Gustaf V Research Institute
Reviewer Comments:
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? ???
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) ???
  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? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  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? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  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? N/A
  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)? N/A
  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