Evidence-based medicine: concepts and practice MCQs With Answer

Introduction

Evidence-based medicine (EBM) is essential for M.Pharm students aiming to optimize medication use through scientifically supported decisions. This blog presents focused multiple-choice questions that cover core EBM concepts and practical skills: forming answerable clinical questions, searching and appraising literature, interpreting measures of effect, understanding trial methodology, and applying evidence to individual patients. Questions emphasize critical appraisal, statistical interpretation (confidence intervals, p-values, heterogeneity), meta-analysis principles, bias recognition, guideline development and shared decision-making. Each MCQ includes plausible distractors and clear answers to reinforce learning, promote deeper thinking about study design and interpretation, and prepare you for exams and clinical practice where rational, patient-centered pharmacotherapy matters.

Q1. What is the best concise definition of evidence-based medicine (EBM)?

• Using only randomized trials to guide all clinical decisions
• Integrating individual clinical expertise with the best available external clinical evidence and patient values
• Relying on expert opinion and textbooks as primary decision sources
• Applying local formulary restrictions to standardize therapy

Correct Answer: Integrating individual clinical expertise with the best available external clinical evidence and patient values

Q2. Which sequence correctly lists the classical five steps of practicing EBM?

• Apply, Ask, Appraise, Acquire, Assess
• Ask, Acquire, Appraise, Apply, Assess
• Ask, Appraise, Acquire, Apply, Audit
• Acquire, Ask, Appraise, Apply, Act

Correct Answer: Ask, Acquire, Appraise, Apply, Assess

Q3. In the PICO framework used to frame clinical questions, what does the letter “C” usually represent?

• Cost of intervention
• Clinical outcome
• Comparison or comparator
• Case series

Correct Answer: Comparison or comparator

Q4. Which type of study is generally considered the highest level of evidence for judging intervention effectiveness?

• Case-control study
• Randomized controlled trial
• Systematic review with meta-analysis of randomized trials
• Expert consensus guideline

Correct Answer: Systematic review with meta-analysis of randomized trials

Q5. What is the primary methodological feature that distinguishes a randomized controlled trial (RCT) from non-randomized studies?

• Use of a control group
• Random allocation of participants to intervention groups
• Blinding of outcome assessors
• Prospective follow-up of participants

Correct Answer: Random allocation of participants to intervention groups

Q6. Allocation concealment in randomized trials is most important to prevent which problem?

• Performance bias after randomization
• Selection bias before or at the point of randomization
• Detection bias during outcome assessment
• Attrition bias due to loss to follow‑up

Correct Answer: Selection bias before or at the point of randomization

Q7. Blinding participants and personnel in a trial primarily reduces which type(s) of bias?

• Selection bias only
• Performance and detection bias
• Publication bias
• Confounding by indication

Correct Answer: Performance and detection bias

Q8. Why is an intention-to-treat (ITT) analysis recommended in randomized trials?

• It excludes participants who did not adhere to the protocol to show the maximal drug effect
• It preserves the benefits of randomization and reduces bias from post-randomization exclusions
• It increases statistical power by removing dropouts
• It allows investigators to change outcomes after seeing the data

Correct Answer: It preserves the benefits of randomization and reduces bias from post-randomization exclusions

Q9. A reported relative risk (RR) for an adverse event with treatment versus control is 0.5. How should this be interpreted?

• The risk is increased by 50% with treatment
• The risk is reduced by 50% with treatment
• The absolute risk reduction is 50% with treatment
• The number needed to treat is 0.5

Correct Answer: The risk is reduced by 50% with treatment

Q10. If the event rate is 20% in the control group and 10% in the treatment group, what is the number needed to treat (NNT) to prevent one event?

• 5
• 10
• 20
• 50

Correct Answer: 10

Q11. Under which condition is an odds ratio (OR) a reasonable approximation of the relative risk (RR)?

• When outcome is common (>20%)
• When outcome is rare (<10%)
• When sample size is very small
• When using adjusted analyses only

Correct Answer: When outcome is rare (<10%)

Q12. A 95% confidence interval for a relative risk is 0.85 to 1.12. What does this imply about statistical significance at the 0.05 level?

• The result is statistically significant because the interval is narrow
• The result is not statistically significant because the interval includes 1
• The p-value must be less than 0.01
• The point estimate is invalid

Correct Answer: The result is not statistically significant because the interval includes 1

Q13. In meta-analysis, what does an I² value of 65% most likely indicate?

• Low heterogeneity between studies
• Moderate to substantial heterogeneity between studies
• No heterogeneity; all variation is due to chance
• High publication bias

Correct Answer: Moderate to substantial heterogeneity between studies

Q14. Which statement best distinguishes fixed-effect and random-effects meta-analysis models?

• Fixed-effect assumes a single true effect size common to all studies; random-effects allows study-level variation in true effects
• Fixed-effect adjusts for publication bias; random-effects does not
• Fixed-effect is used only for binary outcomes; random-effects only for continuous outcomes
• Fixed-effect produces wider confidence intervals than random-effects in all cases

Correct Answer: Fixed-effect assumes a single true effect size common to all studies; random-effects allows study-level variation in true effects

Q15. Asymmetry in a funnel plot is most commonly interpreted as evidence of which issue?

• High internal validity of included studies
• Publication bias or small-study effects
• Correct randomization across trials
• Perfect homogeneity of treatment effects

Correct Answer: Publication bias or small-study effects

Q16. Which of the following is NOT one of the primary domains used by the GRADE system to downgrade the quality of evidence?

• Risk of bias
• Inconsistency
• Indirectness
• Sample size calculation plan

Correct Answer: Sample size calculation plan

Q17. What does the sensitivity of a diagnostic test measure?

• The proportion of true negatives correctly identified
• The proportion of true positives correctly identified
• The probability that a positive test result rules out disease
• The prevalence of disease in the tested population

Correct Answer: The proportion of true positives correctly identified

Q18. How is the positive likelihood ratio (LR+) for a diagnostic test calculated?

• Sensitivity divided by (1 − Specificity)
• Specificity divided by (1 − Sensitivity)
• Sensitivity − Specificity
• (1 − Sensitivity) / Specificity

Correct Answer: Sensitivity divided by (1 − Specificity)

Q19. Which statement about predictive values of diagnostic tests is correct?

• Positive predictive value (PPV) is independent of disease prevalence
• Negative predictive value (NPV) increases as disease prevalence increases
• Both PPV and NPV vary with disease prevalence in the tested population
• Predictive values depend only on test sensitivity, not specificity

Correct Answer: Both PPV and NPV vary with disease prevalence in the tested population

Q20. In evidence-based prescribing, what does shared decision-making primarily emphasize?

• Physician making the decision based on clinical guidelines alone
• Using the most expensive therapy to ensure efficacy
• Combining best evidence with the patient’s values, preferences and circumstances
• Avoiding patient involvement to prevent confusion

Correct Answer: Combining best evidence with the patient’s values, preferences and circumstances

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