EAL

DLM: Major Dietary Components for LDL-Cholesterol Reduction (2001)

Citation:

Hooper L, Summerbell CD, Higgins JPT, Thompson RL, Capps NE, Smith GD, Reimersma RA, Ebrahim S. Dietary fat intake and prevention of cardiovascular disease: systematic review. BMJ. 2001

Worksheet created prior to Spring 2004 using earlier ADA research analysis template.

Study Design:

Meta-analysis or Systematic Review

Class:

M - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

Inclusion Criteria:

Inclusion criteria: 1. adequate randomization, double-blinded 2. healthy adults 3. usual or control diet or placebo group 4. stated aim of intervention was ¯ or modification of intake of dietary fat or cholesterol unless the intervention was exclusively omega 3 fatty acids 5. intervention continued for at least 2 months or follow-up after dietary advise was at least 6 months 6. data on mortality or CVD morbidity were available

Exclusion Criteria:

Exclusion criteria: 1. acutely ill 2. pregnant

Description of Study Protocol:

Treatment effect was measured as a rate ratio and meta-analysis performed as a weighted average of log rate ratios. The meta-analysis used random effects methodology. Meta-analysis pools results of individual trials, with weighting so that results with higher precision (related to sample size) contribute more to the combined outcome. 27 studies (30,902 person years of observation); 1430 deaths, 1216 cardiovascular events.

Data Collection Summary:

Outcome measures: 1. total mortality 2. cardiovascular mortality 3. combined cardiovascular events (CVD deaths, non-fatal MI, stroke, angina, heart failure, peripheral vascular disease, angioplasty, heart failure, CABG, quality of life)

Description of Actual Data Sample:

Summary of Results:

Alteration of dietary fat intake had small effects on total mortality (rate ratio 0.98; 95% CI, 0.86 to 1.12) Cardiovascular mortality was ¯ 9% (0.91; 0.77 to 1.07) Cardiovascular events were ¯ 16% (0.84; 0.72 to 0.99) which was attenuated (0.86;0.72 to 1.03) in a sensitivity analysis that excluded a trial using oily fish. Trials with at least 2 years’ Follow-up provided stronger evidence of protection from cardiovascular events (0.76;0.65 to 0.90)

Author Conclusion:

There is a small but potentially important ¯ in CVD risk with ¯ or modification of dietary fat intake, seen particularly in trials of longer duration (~2 years). There is considerable uncertainty over the size of effects and the means by which they were achieved given the scarcity of trials longer than 2 years’ duration. In this review, we have tried to separate out whether individual fatty acid fractions are responsible for any benefits to health (using the technique of meta-regressiona). The answers are not definitive, the data being too sparse to be convincing. We are left with a suggestion that less total fat or less of any individual fatty acid fraction in the diet is beneficial.

Funding Source:

University/Hospital:

University of London

Not-for-profit

Foundation associated with industry:

Reviewer Comments:

The significance of this study is that 2 years of intervention were necessary to demonstrate any benefit on outcomes. This is interesting in light of the fact that self-management studies for individuals with hyperlipidemia Have been 2 months to 1year. The table summarizing the studies did not specify how often diet intervention was given or who did the intervention (physician, RD or other).

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?	Yes
	3.	Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased?	Yes
	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?	Yes
	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?	Yes
	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