EAL

Cardiovascular Disease and Micronutrients

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To assess and compare the effects of statin with or without the addition of a fixed dose of vitamin E on indices of lipid peroxidation [8-iso- PGF-₂ alpha formation (in vivo)].

Inclusion Criteria:

Hypercholesterolemic subjects with serum cholesterol greater than 200mg per dL
Proven vascular disease (coronary, carotid or peripheral arterial).

Exclusion Criteria:

Children
Adults with serum cholesterol less than 200mg per dL
Adults without proven vascular (coronary, carotid or peripheral arterial) disease.

Description of Study Protocol:

Recruitment: Patients were recruited from two centers, Pisa and Chieti. Patients were informed of the investigational nature of the study and gave written informed consent to participate.
Design: Prospective randomized cross-over trial
Blinding used: None.

Intervention

Subjects were taken off lipid-lowering medication for at least 15 days. Subjects were then randomized to one of two treatments:

Simvastatin 10mg, 20mg or 40mg per day, administered once daily in the evening, titrated to achieve at least 20% reduction of total cholesterol after 60 days
Simvastatin 10mg, 20mg or 40mg per day, administered once daily in the evening, titrated to achieve at least 20% reduction of total cholesterol after 60 days plus 600mg vitamin E per day given twice daily with meals.

Subjects were then crossed over to the alternative treatment.

Statistical Analysis

Main characteristics of the two groups were compared by the Student T-test for unpaired data for continuous variables
Main characteristics of the two groups were compared by the Χ² test for dichotomic variables
Comparisons of treatment effects were performed by repeated-measures ANOVA after verification of normality of distribution
Post-hoc testing was performed by the Fisher protected least significance test
Linear regression analysis was performed by standard methods.

Data Collection Summary:

Timing of Measurements

Serum triglycerides, total cholesterol, HDL-cholesterol, LDL-cholesterol, oxidized LDL, plasma vitamin E and F₂-isoprostane (8-iso-PGF_2alpha) were measured at baseline (twice, then averaged) and also at one and two months with treatment.

Dependent Variables

Total cholesterol: Measured by standard enzymatic colorimetric methods
LDL-cholesterol: Calculated with the Friedewald formula
Oxidized LDL: Measured by ELISA
HDL-cholesterol: Measured by standard enzymatic colorimetric methods
Serum triglycerides: Measured by standard enzymatic colorimetric methods
F₂-isoprostane (8-iso-PGF_2alpha): Eight-hour urine samples (from 11:00 pm to 7:00 am) were collected and the timing and total volume was recorded. Two 50-ml aliquots were stored at -80ºC until extraction after addition of one mmol per liter of the antioxidant 4-hydroxy-TEMPO.

Independent Variables

Vitamin E
Simvastatin.

Description of Actual Data Sample:

Initial N: 43 patients (21 men, 22 women)
Attrition (final N): 43 patients (21 men, 22 women)
Age: 63±11 years
Ethnicity: Not provided
Other relevant demographics: All subjects were hypercholeserolemic (over 200mg per dL)
Location: Two recruiting centers at Pisa and Chieti, Italy.

Summary of Results:

	Simvastatin After One Month	Addition of Vitamin E
Total Cholesterol	26.5% reduction (P<0.001); remained stable after two months	Not significant*
LDL-Cholesterol	37.1% reduction (P<0.001)	Not significant*
Oxidized LDL	Significant reduction (P<0.05) Baseline: 3.16±1.49 Simvastatin for one month: 2.57±1.24	Not significant*
HDL-Cholesterol	Not significant; did not lower	Not significant*
Tryglycerides	28.5% reduction (P<0.01)	Not significant*
F₂-isoprostane (8-iso-PGF_2alpha	33.5% reduction (P<0.05)	Not significant*

* Did not add any lowering effect.

Other Findings

A significant but weak inverse relationship was apparent between vitamin E levels and 8-iso-PGF_2alpha when vitamin E levels were expressed after adjustment for cholesterol (P=0.03)
Total cholesterol and LDL-cholesterol directly and highly significantly correlated with 8-iso-PGF_2alpha excretion
A weak, yet significant direct relationship was noted between 8-iso-PGF_2alpha and triglycerides.

Author Conclusion:

This study showed that in hypercholesterolemic subjects:

Simvastatin substantially reduces indices of enhanced lipid peroxidation in vivo
A regimen with vitamin E adds nothing to the effects of a statin on the same indices
Simvastatin reduces plasma oxidized LDL but vitamin E induces no additional effect.

Funding Source:

Industry:

Merck Sharp & Dohme Co

Pharmaceutical/Dietary Supplement Company:

University/Hospital:

University of Chieti, Center of Excellence on Aging

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?	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")?	No
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?	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?	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?	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?	N/A
	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)?	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