MCQ Quiz-Evidence Evaluation

MCQ Quiz: Evidence Evaluation

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Evidence-based practice is the cornerstone of modern pharmacy, requiring practitioners to expertly evaluate biomedical literature to make informed patient care decisions. For PharmD students, the ability to dissect a clinical trial, interpret statistics, and identify potential bias is a non-negotiable skill. This quiz will test your understanding of study designs, biostatistics, and the principles of critical appraisal needed to distinguish high-quality evidence from flawed research.

1. In the hierarchy of evidence, which of the following study types generally provides the strongest level of evidence for a therapeutic intervention?

  • Case-control study
  • Randomized controlled trial
  • Systematic review or meta-analysis of RCTs
  • Prospective cohort study

Answer: Systematic review or meta-analysis of RCTs

2. A study follows two groups of patients, one that received a new diabetes drug and one that received a placebo, forward in time to measure the incidence of cardiovascular events. What is this study design called?

  • Case report
  • Randomized Controlled Trial (RCT)
  • Cross-sectional study
  • Retrospective cohort study

Answer: Randomized Controlled Trial (RCT)

3. A researcher identifies a group of patients with a rare form of cancer and another group without the cancer. They then look back in time to compare past exposures to a specific chemical. This is an example of a:

  • Case-control study.
  • Randomized controlled trial.
  • Prospective cohort study.
  • Case series.

Answer: Case-control study.

4. A study reports a p-value of 0.03 for the primary endpoint. Assuming an alpha of 0.05, what is the correct interpretation?

  • The result is not statistically significant, and the null hypothesis should be accepted.
  • The result is statistically significant, and the null hypothesis is rejected.
  • There is a 3% chance that the results are correct.
  • The study has low statistical power.

Answer: The result is statistically significant, and the null hypothesis is rejected.

5. A clinical trial for a new blood pressure medication reports that the drug lowers systolic BP by an average of 5 mmHg with a 95% Confidence Interval of [2 mmHg, 8 mmHg]. What does this CI mean?

  • There is a 95% probability that the patient’s blood pressure will drop by exactly 5 mmHg.
  • There is a 95% confidence that the true mean difference in the population lies between 2 mmHg and 8 mmHg.
  • The study results are not statistically significant.
  • 95% of patients in the study had a blood pressure reduction between 2 mmHg and 8 mmHg.

Answer: There is a 95% confidence that the true mean difference in the population lies between 2 mmHg and 8 mmHg.

6. A study finds that a new drug reduces the risk of an adverse event from 4% in the placebo group to 2% in the treatment group. What is the Number Needed to Treat (NNT) to prevent one adverse event?

  • 2
  • 25
  • 50
  • 100

Answer: 50

7. In a clinical trial, “blinding” or “masking” is used to reduce which type of bias?

  • Confounding bias
  • Selection bias
  • Attrition bias
  • Measurement or performance bias

Answer: Measurement or performance bias

8. An “intention-to-treat” (ITT) analysis includes data from:

  • Only the patients who completed the study according to the protocol.
  • All patients who were randomized to a treatment group, regardless of whether they completed the study or adhered to the therapy.
  • Only the patients who experienced the primary outcome.
  • Only the patients in the placebo group.

Answer: All patients who were randomized to a treatment group, regardless of whether they completed the study or adhered to the therapy.

9. What is a surrogate endpoint in a clinical trial?

  • The primary clinical outcome of greatest importance to the patient (e.g., survival).
  • A laboratory measurement or physical sign used as a substitute for a clinically meaningful endpoint (e.g., blood pressure as a surrogate for stroke).
  • The secondary outcome of the study.
  • An outcome that is measured by the patient themselves.

Answer: A laboratory measurement or physical sign used as a substitute for a clinically meaningful endpoint (e.g., blood pressure as a surrogate for stroke).

10. “External validity” of a study refers to:

  • The degree to which the study was conducted without bias.
  • The statistical significance of the results.
  • The generalizability of the study results to other populations, settings, or times.
  • The proper randomization of study participants.

Answer: The generalizability of the study results to other populations, settings, or times.

11. A meta-analysis is a statistical technique used to:

  • Combine the results of multiple studies to produce a single, more precise estimate of effect.
  • Describe a single, interesting patient case.
  • Follow a large group of people over time.
  • Compare two different drug formularies.

Answer: Combine the results of multiple studies to produce a single, more precise estimate of effect.

12. In a forest plot from a meta-analysis, if the diamond representing the overall summary estimate does not touch the line of no effect (null value), the result is considered:

  • Clinically insignificant.
  • Statistically insignificant.
  • Statistically significant.
  • Invalid due to heterogeneity.

Answer: Statistically significant.

13. Selection bias occurs when:

  • The method of choosing subjects for a study leads to a sample that is not representative of the population.
  • Measurements are taken incorrectly.
  • Patients drop out of the study unevenly between groups.
  • The researchers are not blinded to the treatment allocation.

Answer: The method of choosing subjects for a study leads to a sample that is not representative of the population.

14. Which document provides a structured framework and checklist for reporting randomized controlled trials?

  • The Belmont Report
  • The CONSORT Statement
  • The PRISMA Statement
  • The STROBE Statement

Answer: The CONSORT Statement

15. A Type I error in hypothesis testing is when a researcher:

  • Correctly rejects the null hypothesis.
  • Correctly fails to reject the null hypothesis.
  • Incorrectly rejects a true null hypothesis (a false positive).
  • Incorrectly fails to reject a false null hypothesis (a false negative).

Answer: Incorrectly rejects a true null hypothesis (a false positive).

16. In a study comparing Drug A to Drug B, the Relative Risk (RR) for a negative outcome was 0.75 (95% CI [0.60, 0.95]). How is this interpreted?

  • Drug A is associated with a 75% increased risk of the outcome.
  • Drug A is associated with a 25% reduction in the risk of the outcome compared to Drug B.
  • The result is not statistically significant.
  • Drug A is associated with a 75% reduction in the risk of the outcome.

Answer: Drug A is associated with a 25% reduction in the risk of the outcome compared to Drug B.

17. An odds ratio (OR) of 1.0 indicates that:

  • The exposure is associated with a 100% increased risk of the outcome.
  • The exposure is protective.
  • There is no association between the exposure and the outcome.
  • The study results are invalid.

Answer: There is no association between the exposure and the outcome.

18. What is a primary limitation of a case report as a form of evidence?

  • It provides strong evidence for causation.
  • It is not possible to generalize the findings from a single patient.
  • It involves a large number of subjects.
  • It is always a prospective study.

Answer: It is not possible to generalize the findings from a single patient.

19. A study’s power is the probability of:

  • Making a Type I error.
  • Making a Type II error.
  • Avoiding a Type I error.
  • Correctly rejecting a false null hypothesis (i.e., detecting a true effect).

Answer: Correctly rejecting a false null hypothesis (i.e., detecting a true effect).

20. A “non-inferiority” trial is designed to show that a new treatment is:

  • Superior to the standard treatment.
  • Not unacceptably worse than the standard treatment.
  • Equivalent to a placebo.
  • The most cost-effective option available.

Answer: Not unacceptably worse than the standard treatment.

21. “Confounding” occurs when:

  • A third variable is associated with both the exposure and the outcome, distorting the true relationship between them.
  • The results of a study are not statistically significant.
  • Patients are lost to follow-up.
  • The researchers are aware of the treatment allocation.

Answer: A third variable is associated with both the exposure and the outcome, distorting the true relationship between them.

22. Which is an example of nominal data?

  • Patient’s temperature in Celsius.
  • Pain score on a scale of 1 to 10.
  • Patient’s blood type (A, B, AB, O).
  • Patient’s weight in kilograms.

Answer: Patient’s blood type (A, B, AB, O).

23. The statistical test most appropriate for comparing the mean blood pressure between two independent groups is the:

  • Chi-square test
  • Paired t-test
  • Independent samples t-test
  • ANOVA

Answer: Independent samples t-test

24. A cross-sectional study measures:

  • The incidence of a new disease over time.
  • The outcomes of a new intervention.
  • Exposures and outcomes at a single point in time.
  • Past exposures in patients with a known disease.

Answer: Exposures and outcomes at a single point in time.

25. Recall bias is a major concern in which type of study design?

  • Randomized controlled trial
  • Prospective cohort study
  • Retrospective case-control study
  • Meta-analysis

Answer: Retrospective case-control study

26. The PICO format helps a clinician formulate an answerable clinical question. The “C” in PICO stands for:

  • Causation
  • Correlation
  • Comparison or Control
  • Conclusion

Answer: Comparison or Control

27. Clinical practice guidelines are designed to:

  • Be followed rigidly without any clinical judgment.
  • Provide recommendations for optimizing patient care based on a systematic review of evidence.
  • Replace the need for primary literature.
  • Promote the use of the most expensive medications.

Answer: Provide recommendations for optimizing patient care based on a systematic review of evidence.

28. A key difference between a systematic review and a traditional narrative review is that a systematic review:

  • Is based on the author’s opinion.
  • Uses explicit, pre-specified methods to identify, select, and appraise relevant research.
  • Includes only studies published in the last year.
  • Never includes a statistical summary.

Answer: Uses explicit, pre-specified methods to identify, select, and appraise relevant research.

29. Attrition bias is a concern when:

  • The study sample is not representative of the population.
  • There are systematic differences in the loss of subjects between the study groups.
  • The outcome is measured incorrectly.
  • The study lacks a control group.

Answer: There are systematic differences in the loss of subjects between the study groups.

30. What does the term “statistical significance” mean?

  • The observed effect is large and important to patients.
  • The observed effect is unlikely to be due to random chance alone.
  • The study was conducted perfectly without any bias.
  • The treatment is 100% effective.

Answer: The observed effect is unlikely to be due to random chance alone.

31. The primary purpose of randomization in an RCT is to:

  • Make the study groups comparable with respect to known and unknown confounding variables.
  • Ensure that the researchers can choose which patients go into which group.
  • Make the study less expensive to conduct.
  • Guarantee the results will be positive.

Answer: Make the study groups comparable with respect to known and unknown confounding variables.

32. A per-protocol analysis is more likely than an intention-to-treat analysis to:

  • Underestimate the effect of a drug.
  • Overestimate the efficacy of a drug by excluding non-adherent patients.
  • Be the preferred primary analysis for a superiority trial.
  • Include all randomized patients regardless of adherence.

Answer: Overestimate the efficacy of a drug by excluding non-adherent patients.

33. The GRADE system is used in clinical guidelines to:

  • Grade the quality of the evidence and the strength of the recommendations.
  • Rank journals based on their impact factor.
  • Score medical students on their exams.
  • Determine the cost-effectiveness of a drug.

Answer: Grade the quality of the evidence and the strength of the recommendations.

34. Publication bias in a meta-analysis refers to the phenomenon that:

  • Studies with positive or statistically significant results are more likely to be published than those with negative results.
  • Journals only publish articles from famous authors.
  • Only studies written in English are included.
  • All studies on a topic are published with equal probability.

Answer: Studies with positive or statistically significant results are more likely to be published than those with negative results.

35. A “drug evaluation monograph” is primarily used by:

  • Patients to learn about side effects.
  • Pharmacy and Therapeutics (P&T) committees to make formulary decisions.
  • The FDA during the drug approval process.
  • Pharmaceutical companies for marketing.

Answer: Pharmacy and Therapeutics (P&T) committees to make formulary decisions.

36. A clinically important difference is:

  • Any difference that has a p-value less than 0.05.
  • A change in a surrogate marker.
  • A difference in outcome that is meaningful to the patient, regardless of its statistical significance.
  • Always the same as the statistically significant difference.

Answer: A difference in outcome that is meaningful to the patient, regardless of its statistical significance.

37. When critically appraising a study, the first question to ask should be about the study’s:

  • Internal validity.
  • Cost.
  • Author credentials.
  • Publication date.

Answer: Internal validity.

38. Which type of database would you use to find primary literature articles?

  • A tertiary resource like a textbook.
  • A secondary resource like PubMed or Embase.
  • A drug manufacturer’s website.
  • A social media platform.

Answer: A secondary resource like PubMed or Embase.

39. A “washout period” is used in which type of study design?

  • Parallel RCT
  • Cross-sectional study
  • Crossover RCT
  • Case-control study

Answer: Crossover RCT

40. The measure of central tendency that is most affected by extreme outliers is the:

  • Mean
  • Median
  • Mode
  • Range

Answer: Mean

41. The strength of a prospective cohort study is that it can:

  • Establish causality definitively.
  • Be completed quickly and inexpensively.
  • Determine the incidence of a disease and investigate potential risk factors.
  • Avoid any loss to follow-up.

Answer: Determine the incidence of a disease and investigate potential risk factors.

42. A conflict of interest in a clinical trial is a concern because it may:

  • Improve the validity of the study.
  • Introduce bias into the study’s design, conduct, or reporting.
  • Reduce the cost of the study.
  • It is not a concern.

Answer: Introduce bias into the study’s design, conduct, or reporting.

43. A hazard ratio (HR) of 0.80 for mortality means that at any point in time, the treatment group had:

  • An 80% higher rate of death than the control group.
  • A 20% higher rate of death than the control group.
  • A 20% lower rate of death than the control group.
  • An 80% lower rate of death than the control group.

Answer: A 20% lower rate of death than the control group.

44. What is a key limitation of using a surrogate endpoint like cholesterol levels instead of a clinical endpoint like myocardial infarction?

  • Surrogate endpoints are more difficult to measure.
  • A change in the surrogate may not always translate to a meaningful clinical benefit.
  • Surrogate endpoints are more meaningful to patients.
  • Clinical endpoints are less reliable.

Answer: A change in the surrogate may not always translate to a meaningful clinical benefit.

45. Which of the following is a tertiary source of drug information?

  • A randomized controlled trial published in the NEJM.
  • A textbook chapter summarizing the treatment of hypertension.
  • A meta-analysis of multiple clinical trials.
  • A case report about a single patient.

Answer: A textbook chapter summarizing the treatment of hypertension.

46. When evaluating an article, you find that the baseline characteristics between the treatment and control groups are significantly different. This indicates a potential failure of:

  • Blinding
  • Randomization
  • Statistical analysis
  • The primary endpoint measurement

Answer: Randomization

47. A “patient-reported outcome” (PRO) is a health outcome that is:

  • Measured directly by a laboratory test.
  • Based on a clinician’s physical exam.
  • Reported directly from the patient without interpretation by a clinician.
  • Always a surrogate marker.

Answer: Reported directly from the patient without interpretation by a clinician.

48. Sensitivity of a diagnostic test refers to its ability to:

  • Correctly identify those who do not have the disease.
  • Correctly identify those who have the disease.
  • Provide a result quickly.
  • Work in all patient populations.

Answer: Correctly identify those who have the disease.

49. Specificity of a diagnostic test refers to its ability to:

  • Correctly identify those who do not have the disease.
  • Correctly identify those who have the disease.
  • Be performed by any healthcare professional.
  • Use a small amount of blood sample.

Answer: Correctly identify those who do not have the disease.

50. The ultimate goal of evidence evaluation in pharmacy practice is to:

  • Find flaws in every published study.
  • Memorize p-values and confidence intervals.
  • Apply the best available evidence to make informed decisions for individual patient care.
  • Rely solely on personal experience.

Answer: Apply the best available evidence to make informed decisions for individual patient care.

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