EAL

DLM: Vitamin E (2001)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Should vitamin E be routinely used as a preventative agent for individuals at risk for CVD?

Inclusion Criteria:

Prospective observational studies:

U.S. Nurses' Health Study
U.S. Health Professionals' Follow-up Study
Iowa Women's Health Study
Established Populations for Epidemiologic Studies of the Elderly.

Randomized, controlled trials:

Cambridge Heart Antioxidant Study
Alpha-tocopherol, Beta-carotene Cancer Prevention Study.

Exclusion Criteria:

not described

Description of Study Protocol:

4 prospective observation studies 1. NHS 2. 87,245 female nurses for 8 years; outcome measures: nonfatal & fatal MI HPS 3. 39,910 male health professionals for 4 years; outcome measures: nonfatal & fatal MI EPESE 4. 11,178 men & women >65 years of age for 10 years; outcome measure: cardiac mortality. IWHS 34,387 postmenopausal women for 6 years; outcome measure: cardiac mortality. 2 RCT (fatal & nonfatal MI) ATBC 27,271 male Finnish smokers for 5-8 years. CHAOS 2002 British men & women with CAD followed for 1-3 years.

Data Collection Summary:

This is a narrative review. There is no description of search method or how studies were retreived.

Description of Actual Data Sample:

Not applicable - this is a narrative review.

Summary of Results:

Prospective:

NHS 41% ¯ in nonfatal & fatal MI; highest in those receiving >100 IU/d >2 years; 34% reduction in risk of cardiac events.

HPS 37% ¯ in nonfatal & fatal MI; highest in those receiving >100 IU/d > 2 years; 39% lower risk of heart disease, as manifested by ischemic events and the need for cardiac surgery.

EPESE ¯ 63% decrease in risk of death from coronary heart disease in long term users; 47% reduction in mortality for use of supplements for anytime, even short-term.

IWHS 38% relative risk in cardiac mortality in the group with the highest quintile of intake; benefit was from vitamin in diet not supplements.

Clinical trials:

ATBC nonsignificant (8 %) ¯ in fatal MI (P< 0.75).

CHAOS 77% ¯ in nonfatal MI (P=0.05); 47% ¯ in total MI (fatal & nonfatal) with 400 or 800 IU vitamin E. Only 1 RCT (CHAOS) could be generalized and this was a 2° Prevention trial; this trial suggested that patients with existing CAD appear to benefit from use of vitamin E, however, CHAOS failed to demonstrate any mortality benefit from vitamin E.

Author Conclusion:

Studies to evaluate the benefits of vitamin E in the prevention of CVD need to be at least 2 years in length. Limited studies have been done at this time, and while evidence is mounting, results are still somewhat contradictory.

Funding Source:

University/Hospital:

Lancaster General Hospital

Reviewer Comments:

Quality Criteria Checklist: Review Articles
Relevance Questions
	1.	Will the answer if true, have a direct bearing on the health of patients?	Yes
	2.	Is the outcome or topic something that patients/clients/population groups would care about?	Yes
	3.	Is the problem addressed in the review one that is relevant to dietetics practice?	Yes
	4.	Will the information, if true, require a change in practice?	Yes

Validity Questions
	1.	Was the question for the review clearly focused and appropriate?	Yes
	2.	Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described?	No
	3.	Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased?	No
	4.	Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible?	No
	5.	Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined?	Yes
	6.	Was the outcome of interest clearly indicated? Were other potential harms and benefits considered?	Yes
	7.	Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described?	No
	8.	Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included?	???
	9.	Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed?	Yes
	10.	Was bias due to the review's funding or sponsorship unlikely?	Yes