EAL

DF: Cardiovascular Disease (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine the effects of fiber, from grain, citrus and vegetables, on serum total cholesterol and triglyerides in individuals with mild Essential Arterial Hypertension.

Inclusion Criteria:

Mild Essential Arterial Hypertension, first WHO stage
No previous antihypertensive therapy
Under 65 years of age.

Exclusion Criteria:

Coronary heart disease
Chronic renal failure as defined by serum creatinine over 1.5mg per dL
Liver disease
Gastrointestinal disorders
Diabetes mellitus
Recent surgical treatment on gastrointestinal tract
Dysendocrinia
Signs of toxic dependance of alcohol abuse
Poor compliance
Body weight over 30% of ideal body weight
Pregnancy
Lactation
Patients using antacids
Patients using H2-Blockers
Patients using bulk laxatives or other drugs affecting the gastrointestinal tract.

Description of Study Protocol:

Recruitment: Not described
Design: Randomized placebo-controlled study of 16 hypertenive patients to supplementation with fiber (3.5g or seven grams guar, containing 56% to 58% fiber from grain, citrus and vegetables) for two weeks. A one-week run-in period occurred before treatment.
Blinding used: Double-blinded placebo-controlled.

Intervention

Subjects were randomly-assigned to consume either 3.5g or seven grams fiber supplementation
Following a 12-hour fast, subjects consumed either 10 or 20 fiber tablets per day.

Statistical Analysis

Means with Standard Deviation
Student’s T-test (paired data).

Data Collection Summary:

Timing of Measurements

The following data was collected daily during the run-in:

Weight
Height
Qualitative Evaulation of the Alvus
Daily morning heart rate, supine after a 10-minute rest
Daily morning heart rate, upright after a two-minute rest
Daily morning blood pressure, supine after a 10-minute rest
Daily morning blood pressure, upright after a two-minute rest.

The following data was collected daily during the intervention, after a 12-hour fast:

Weight
Height
Qualitative evaulation of the alvus
Daily morning heart rate, supine after a 10-minute rest
Daily morning heart rate, upright after a two-minute rest
Daily morning blood pressure, supine after a 10-minute rest
Daily morning blood pressure, upright after a two-minute rest.

The following data was collected before and after the treatment:

24-hour urine collection
Red blood cell count
White blood cell count
Hematocrit
Hemoglobin
Blood platelets
MCHC
MCH
MCV
Serum total cholesterol
Serum triglycerides
HDL-cholesterol
Serum creatinine
Urinary daily volume
Serum and urinary calcium
Serum sodium
Serum potassium
Serum chloride
Plasma aldesteronesuspine, after a two-hour rest
Plasma aldesterone standing, after one hour, upright
Plasma cortisol, at 8:00 am and 12:00 am
Adrenocorticotropin, at 8:00 am and 12:00 am.

The following data was collected at zero, 30, 60, 90, 120, 150, 180 and 240 minutes post-prandial of the two test meals:

Serum glucose
C-peptide assay.

Dependent Variables

Serum total cholesterol
Serum HDL-cholesterol
Systolic blood pressure
Diastolic blood pressure.

Independent Variables

Fiber intake.

Description of Actual Data Sample:

Initial N

Six males, 10 females

Group A (10 fiber tablets, 10 placebo): Three males, five females
Group B (20 fiber tablets): Three males, five females.

Attrition

Not described.

Age

Group A (10 fiber tablets, 10 placebo): 47.7±14.7 years
Group B (20 fiber tablets): 43.2±3.3 years.

Ethnicity

Not described.

Anthropometrics

Body weight (kg)
Group A (10 fiber tablets, 10 placebo): 72.2±8.2
Group B (20 fiber tablets): 75.4±12.7.

Location

University of Siena, Piazza Duomo Medical Department; Milano, Italy.

Summary of Results:

Supine systolic blood pressure (mmHg): Significantly lower following the 20-tablet-per-day fiber supplement. P-value between groups, >0.16 (161.2±9.9mmHg, P<0.01; 145.6±10.5mmHg, P<0.01).
Supine diastolic blood pressure (mmHg): Significantly lower following the 20-tablet-per-day fiber supplement. P-value between groups, <0.05 (98.9±3.2mmHg, P<0.01; 90.0±2.7mmHg, P<0.01).
Standing diastolic blood pressure (mmHg): Significantly lower following the 20-tablet-per-day fiber supplement. P-value between groups, <0.05 (161.2±9.9mmHg, P<0.01; 144.0±10.2mmHg, P<0.01).
Serum total cholesterol: P-value between groups, >0.83 (252.7±32.7mg per dL, P<0.05; 219.1±40.3mg per dL, P<0.05)
Serum triglycerides: P-value between groups, >0.79 (197.5±46.7mg per dL, P<0.05; 148.7±42.8mg per dL, P<0.05).

Author Conclusion:

Limited study reveals possible blood pressure-lowering effect of fiber supplement on non-overweight untreated patients with mild essential aterial hypertension.

Funding Source:

Reviewer Comments:

Small sample size
Limited presentation of demographic data
Large difference in age
No crossover design
No power calculation presented
No description of diet composition
No description of randomization scheme
No description of diet tolerance.

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?	No
3.	Were study groups comparable?		No
	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%.)	N/A
	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?		Yes
	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?		No
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	No
	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?	No
	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?	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?	No
	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)?	No
	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