CET Research Methods & Evidence-Based Practice 2 — Questions and Answers
Question 1: In a randomized controlled trial evaluating a new echocardiographic protocol, which element is MOST critical for minimizing selection bias?
- Blinding the sonographers
- Random allocation of participants to groups (Correct answer)
- Using a large sample size
- Standardizing equipment across sites
Correct answer: Random allocation of participants to groups
Random allocation ensures that known and unknown confounders are evenly distributed between groups, directly minimizing selection bias.
Question 2: A meta-analysis of studies on diastolic dysfunction grading reports high statistical heterogeneity (I²=85%). What does this indicate?
- The pooled result is highly reliable
- There is significant variability in results across studies (Correct answer)
- The sample sizes were too small
- Publication bias is present
Correct answer: There is significant variability in results across studies
An I² of 85% indicates substantial heterogeneity, meaning the variability in study results is greater than expected by chance alone.
Question 3: Which study design is BEST suited to determine the incidence of new-onset atrial fibrillation detected by echocardiography in a healthy population over 10 years?
- Cross-sectional study
- Case-control study
- Prospective cohort study (Correct answer)
- Randomized controlled trial
Correct answer: Prospective cohort study
A prospective cohort study follows a disease-free population over time, making it ideal for measuring incidence of new conditions.
Question 4: When applying evidence-based practice, a CET finds a Level I systematic review and a Level III expert opinion supporting different LVEF measurement techniques. Which should guide practice?
- Expert opinion, as it reflects real-world experience
- The systematic review, as it represents the highest level of evidence (Correct answer)
- Neither, until an RCT is available
- Whichever is more recent
Correct answer: The systematic review, as it represents the highest level of evidence
Level I systematic reviews sit at the top of the evidence hierarchy and should take precedence over expert opinion in guiding clinical practice.
Question 5: A study reports that 3D echocardiography has a sensitivity of 92% and specificity of 88% for detecting apical thrombus. What does specificity of 88% mean?
- 88% of patients with thrombus were correctly identified
- 88% of patients without thrombus were correctly identified as negative (Correct answer)
- 12% of all tests were inconclusive
- 88% of positive results are true positives
Correct answer: 88% of patients without thrombus were correctly identified as negative
Specificity is the ability of a test to correctly identify true negatives — patients who do not have the condition.
Question 6: Which statistical measure is used to express the precision of a sample mean and is commonly reported in echocardiographic measurement studies?
- Standard deviation
- Interquartile range
- Standard error of the mean (Correct answer)
- Confidence interval width
Correct answer: Standard error of the mean
The standard error of the mean (SEM) quantifies how precisely the sample mean estimates the population mean.
Question 7: A new guideline on mitral regurgitation grading is published. According to evidence-based practice principles, what is the FIRST step a CET should take?
- Immediately implement the guideline in all patients
- Critically appraise the guideline for validity and applicability (Correct answer)
- Wait for institutional approval before reading it
- Ask a physician to interpret it
Correct answer: Critically appraise the guideline for validity and applicability
Critical appraisal of the guideline's methodology and applicability to one's patient population is the first EBP step before implementation.
CET Research Methods & Evidence-Based Practice 2
In a randomized controlled trial evaluating a new echocardiographic protocol, which element is MOST critical for minimizing selection bias?