Slide Presentation from the AHRQ 2008 Annual Conference
On September 10, 2008, Joseph Lau, made this presentation at the 2008 Annual Conference. Select to access the PowerPoint® presentation (195 KB; Plugin Software Help).
Methodological Issues in Systematic Review—Formulating Questions
- Joseph Lau, MD
Tufts Medical Center Evidence-based Practice Center (EPC)
- AHRQ Annual Meeting
September 10, 2008
Evidence Report/Technology Assessment
- Cover of Evidence Report/Technology Assessment: Effects of Omega-3 Fatty Acids on Cardiovascular Disease.
Analytic framework for omega-3 Fatty Acid (FA) intake and Cardiovascular Disease (CVD)
- Diagram depicts relationships among:
- Target populations.
- Omega-3 Fatty Acid Consumption.
- Adverse Events.
- Tissue/Plasma Levels.
- Intermediate Outcomes/Biological Effects.
- Clinical Outcomes.
Specific Key Questions
- What is the efficacy or association of omega-3 fatty acids (DHA, EPA or ALA supplements, and fish consumption) in reducing CVD events (including all-cause mortality, CVD mortality, non-fatal CVD events, and new diagnosis of CVD)? In patients without known CVD (primary prevention) and with known CVD (secondary prevention).
Specific Key Questions
- Relative effects of omega-3 fatty acid sources, with specific emphasis on compositions, dosages, the ratio of omega-6 to omega-3 fatty acids, and potential interactions due to duration of intervention or exposure.
- What adverse events related to omega-3 fatty acid dietary supplements are reported in studies?
- Primary Prevention—patients without prior history of cardiovascular disease.
- Background diet.
- Secondary Prevention—patients with prior history of cardiovascular disease.
- Different kinds, preparation, amount, how intake was estimated.
- Fish oil supplements:
- Eicosapentaenoic acid (EPA)/ Docosahexaenoic acid (DHA).
- α-linolenic acid [ALA] (walnut, canola oil, flax seed, etc.)
- Clinical outcomes (events).
- Overall mortality.
- Myocardial infarction.
- Sudden death.
- Surrogate/intermediate outcomes (biomarkers, measurements).
- Blood pressure.
- Lipid levels.
The PICO method to formulate research question on interventions
- Table lists Participants—Interventions—Comparator—Outcomes (PICO):
- Primary prevention—Fish, fish oil, ALA—Placebo—Overall mortality.
- Secondary prevention—Dosage—No control—Sudden death.
- (Blank)—Background intake—Active comparator—Revascularization.
- (Blank)—(blank)—(blank)—Blood pressure.
- Randomized controlled trial (RCT).
- Other criteria.
- Study size.
- Year, language, etc.
Additional inclusion criteria
- Published English language literature.
- Experimental or observational studies.
- Reported original CVD outcome data and evaluated any potential source of omega-3 fatty acids.
- At least 5 human subjects.
- At least 1-year duration.
Issues in formulating a question
- Narrow versus broad (for individual or population).
- Clinically meaningful and useful (based on sound biological and epidemiological principles).
- Very broadly defined questions may be criticized for mixing apples and oranges.
- Very narrowly focused questions may have no data or have limited generalizability and sometimes may lead to misinterpretations.
Current as of January 2009
Methodological Issues in Systematic Review: Formulating Questions. Slide Presentation from the AHRQ 2008 Annual Conference (Text Version). January 2009. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/about/annualmtg08/091008slides/Lau.htm