General Surgery Board Review Research & Evidence-Based Practice 4 — Questions and Answers
Question 1: Which ethical principle is most directly upheld by requiring written informed consent before enrolling a patient in a surgical trial?
- Beneficence
- Justice
- Autonomy (Correct answer)
- Non-maleficence
Correct answer: Autonomy
Informed consent respects patient autonomy by ensuring individuals voluntarily agree to participate with full understanding of risks and alternatives.
Question 2: A 'pragmatic' RCT design differs from an 'explanatory' RCT primarily in that it:
- Uses stricter eligibility criteria to minimize confounding
- Evaluates interventions under real-world clinical conditions (Correct answer)
- Requires blinding of both participants and surgeons
- Measures only surrogate endpoints to speed completion
Correct answer: Evaluates interventions under real-world clinical conditions
Pragmatic trials evaluate effectiveness in routine clinical practice rather than efficacy under tightly controlled conditions.
Question 3: Heterogeneity in a meta-analysis is quantified by the I² statistic. An I² of 75% indicates:
- Minimal heterogeneity; a fixed-effects model is appropriate
- Moderate heterogeneity that does not affect pooling
- Substantial heterogeneity suggesting caution in interpreting the pooled estimate (Correct answer)
- That 75% of studies should be excluded from the analysis
Correct answer: Substantial heterogeneity suggesting caution in interpreting the pooled estimate
I² > 50–75% indicates substantial heterogeneity, which means study results vary considerably and the pooled estimate must be interpreted cautiously.
Question 4: A surgeon designing a study to evaluate a rare complication (incidence 2%) after hernia repair needs to detect a 50% relative risk reduction. This study will most likely require:
- A small sample with short follow-up
- A very large sample size due to low event rate (Correct answer)
- A case-series design to detect the reduction
- A crossover trial with the patient serving as their own control
Correct answer: A very large sample size due to low event rate
Low baseline event rates require large sample sizes to have adequate power to detect clinically meaningful differences.
Question 5: The Hawthorne effect in surgical research refers to:
- Bias introduced when surgeons are aware of which patients are being observed
- Patients changing their behavior because they know they are being studied (Correct answer)
- Improved outcomes due to the novelty of a new surgical technique
- Regression to the mean in repeated outcome measurements
Correct answer: Patients changing their behavior because they know they are being studied
The Hawthorne effect occurs when study participants alter their behavior because they are aware of being observed, potentially confounding results.
Question 6: Which of the following is a surrogate endpoint, rather than a patient-centered outcome, in a colorectal cancer surgical trial?
- Overall survival at 5 years
- Disease-free survival at 3 years
- Carcinoembryonic antigen (CEA) level at 6 months (Correct answer)
- Quality of life at 12 months postoperatively
Correct answer: Carcinoembryonic antigen (CEA) level at 6 months
CEA level is a laboratory biomarker (surrogate), whereas survival and quality of life are direct patient-centered outcomes.
Question 7: In a multicenter surgical RCT, 'cluster randomization' means that:
- Individual patients are randomized within matched pairs
- Entire hospitals or surgical units, not individual patients, are randomized to treatment (Correct answer)
- Patients are randomized in groups based on disease severity clusters
- The randomization sequence is generated in clusters of 10
Correct answer: Entire hospitals or surgical units, not individual patients, are randomized to treatment
Cluster randomization assigns groups (e.g., hospitals or surgical teams) rather than individuals to interventions, reducing contamination between arms.
General Surgery Board Review Research & Evidence-Based Practice 4
Which ethical principle is most directly upheld by requiring written informed consent before enrolling a patient in a surgical trial?