CSC Research & Evidence-Based Practice 2 ā Questions and Answers
Question 1: In a randomized controlled trial for a new antiarrhythmic drug, the p-value is 0.03. Which statement best interprets this finding?
- There is a 3% probability the null hypothesis is true
- There is a 3% probability of observing results this extreme if the null hypothesis is true (Correct answer)
- The drug is clinically significant with 97% certainty
- The study has a 3% false-negative rate
Correct answer: There is a 3% probability of observing results this extreme if the null hypothesis is true
A p-value of 0.03 means there is a 3% probability of observing results at least this extreme assuming the null hypothesis is true.
Question 2: A cardiologist wants to evaluate long-term outcomes of TAVR vs. SAVR in high-risk patients. Which study design is most appropriate if randomization is not feasible?
- Case-control study
- Prospective cohort study (Correct answer)
- Cross-sectional study
- Randomized crossover trial
Correct answer: Prospective cohort study
A prospective cohort study follows participants forward in time, allowing assessment of long-term outcomes when randomization is not feasible.
Question 3: Which statistical measure best quantifies the absolute benefit of a cardiac intervention compared to control?
- Relative risk reduction
- Odds ratio
- Absolute risk reduction (Correct answer)
- Number needed to harm
Correct answer: Absolute risk reduction
Absolute risk reduction (ARR) directly quantifies the difference in event rates between treatment and control groups.
Question 4: In a meta-analysis of statin trials, significant heterogeneity (IĀ² = 75%) is detected. What is the most appropriate next step?
- Proceed with a fixed-effects model
- Exclude all outlier studies
- Perform subgroup analyses to explore sources of heterogeneity (Correct answer)
- Report only the pooled estimate without qualification
Correct answer: Perform subgroup analyses to explore sources of heterogeneity
High IĀ² values indicate substantial heterogeneity; subgroup or sensitivity analyses help identify clinical or methodological sources.
Question 5: A clinical guideline recommends beta-blockers post-MI with a Class I, Level A recommendation. What does Level A indicate?
- Expert consensus opinion only
- Data from a single randomized trial
- Data derived from multiple randomized controlled trials or meta-analyses (Correct answer)
- Data from observational studies or registries
Correct answer: Data derived from multiple randomized controlled trials or meta-analyses
Level of Evidence A indicates the recommendation is supported by data from multiple randomized controlled trials or meta-analyses.
Question 6: Which type of bias occurs when sicker patients are more likely to receive an experimental cardiac device, making the device appear less effective?
- Recall bias
- Selection bias (confounding by indication) (Correct answer)
- Hawthorne effect
- Publication bias
Correct answer: Selection bias (confounding by indication)
Confounding by indication is a form of selection bias where treatment assignment is driven by disease severity, distorting outcome comparisons.
Question 7: A cardiac nurse practitioner is applying an evidence-based guideline to a patient with heart failure and CKD stage 4. The original trial excluded patients with GFR < 30. What EBP step is most relevant here?
- Formulating the PICO question
- Appraising the evidence for applicability to the individual patient (Correct answer)
- Searching the literature for primary sources
- Evaluating outcomes after applying the guideline
Correct answer: Appraising the evidence for applicability to the individual patient
After appraising evidence quality, clinicians must critically assess whether study findings apply to patients who differ from the trial population.
CSC Research & Evidence-Based Practice 2
In a randomized controlled trial for a new antiarrhythmic drug, the p-value is 0.03.
Which statement best interprets this finding?