BMAT Research & Evidence-Based Practice 3 ā Questions and Answers
Question 1: In a meta-analysis, high heterogeneity (IĀ² = 85%) indicates:
- Results across studies are highly consistent
- A fixed-effects model is most appropriate
- Substantial variation in results exists across studies (Correct answer)
- The pooled effect estimate is unreliable due to small sample sizes
Correct answer: Substantial variation in results exists across studies
IĀ² above 75% is considered high heterogeneity, meaning study results vary considerably beyond what chance alone would predict.
Question 2: A case-control study is particularly well-suited for investigating:
- Rare diseases with long latency periods (Correct answer)
- Common acute illnesses
- The incidence of disease in a population
- The efficacy of preventive interventions
Correct answer: Rare diseases with long latency periods
Case-control studies efficiently study rare diseases because cases are sampled based on outcome, not waiting for events to occur.
Question 3: Which of the following is an example of confounding in an epidemiological study?
- Participants who know their treatment assignment change their behavior
- Alcohol consumption is associated with both smoking and lung cancer, masking the true effect (Correct answer)
- Outcome assessors are not blinded to exposure status
- Participants are not randomly assigned to treatment groups
Correct answer: Alcohol consumption is associated with both smoking and lung cancer, masking the true effect
Confounding occurs when a third variable (e.g., smoking) is associated with both the exposure and the outcome, distorting the apparent relationship.
Question 4: Which level of evidence is generally considered highest in the evidence hierarchy for questions about treatment effectiveness?
- Expert consensus opinion
- Well-designed cohort study
- Systematic review of RCTs (Correct answer)
- Single large RCT
Correct answer: Systematic review of RCTs
Systematic reviews that pool multiple high-quality RCTs provide the most reliable evidence about treatment effectiveness.
Question 5: Intention-to-treat (ITT) analysis in an RCT means:
- Only participants who complete the trial are analyzed
- Participants are analyzed according to the treatment they actually received
- All randomized participants are analyzed in their assigned groups regardless of compliance (Correct answer)
- The analysis excludes protocol violators
Correct answer: All randomized participants are analyzed in their assigned groups regardless of compliance
ITT preserves randomization and provides a conservative, pragmatic estimate of treatment effectiveness under real-world conditions.
Question 6: A funnel plot that is asymmetric in a meta-analysis most likely suggests:
- High statistical power across studies
- Absence of confounding variables
- Publication bias or small-study effects (Correct answer)
- Homogeneity of included study populations
Correct answer: Publication bias or small-study effects
Asymmetry in a funnel plot indicates that small studies with negative results may be missing, a hallmark of publication bias.
Question 7: In evidence-based medicine, the PICO framework stands for:
- Population, Intervention, Comparison, Outcome (Correct answer)
- Patient, Incidence, Control, Objective
- Problem, Inquiry, Criterion, Observation
- Prevalence, Intervention, Cohort, Odds
Correct answer: Population, Intervention, Comparison, Outcome
PICO (Population, Intervention, Comparison, Outcome) structures a clinical question to guide efficient literature searching.
BMAT Research & Evidence-Based Practice 3
In a meta-analysis, high heterogeneity (IĀ² = 85%) indicates: