CSR Research Methods & Evidence-Based Practice 3 — Questions and Answers
Question 1: A renal dietitian conducts a literature search and finds 12 relevant RCTs on protein intake and GFR decline. To determine which studies to include in a systematic review, she uses predefined inclusion and exclusion criteria. This step is best described as:
- Data extraction
- Quality appraisal
- Study eligibility screening (Correct answer)
- Sensitivity analysis
Correct answer: Study eligibility screening
Study eligibility screening applies predefined criteria to determine which studies meet the requirements for inclusion in the systematic review.
Question 2: In evaluating a cohort study on dietary fiber and CKD progression, which of the following best represents an example of confounding?
- Participants who eat more fiber also exercise more, and exercise independently affects CKD progression (Correct answer)
- The GFR measurement tool was inaccurate
- Follow-up was only 6 months
- Fiber intake was assessed via 24-hour recall
Correct answer: Participants who eat more fiber also exercise more, and exercise independently affects CKD progression
Confounding occurs when a third variable (exercise) is associated with both the exposure (fiber) and outcome (CKD progression), distorting the true relationship.
Question 3: A nephrologist proposes publishing a case report on a CKD patient who achieved significant eGFR stabilization through a plant-based renal diet. What is the primary limitation of case reports in evidence-based renal nutrition practice?
- They are not peer-reviewed
- They lack a comparison group and cannot establish causality (Correct answer)
- They are too expensive to conduct
- They do not measure dietary intake accurately
Correct answer: They lack a comparison group and cannot establish causality
Case reports describe individual observations without controls, making it impossible to attribute outcomes to the intervention rather than chance or other factors.
Question 4: When calculating the sample size for a CKD dietary intervention study, a researcher sets alpha at 0.05 and power at 80%. What does the 80% power signify in this context?
- There is an 80% chance of committing a Type I error
- The study has an 80% probability of detecting a true effect if one exists (Correct answer)
- 80% of participants are expected to adhere to the diet
- The intervention will work in 80% of patients
Correct answer: The study has an 80% probability of detecting a true effect if one exists
Statistical power (1-β) is the probability of correctly rejecting the null hypothesis when the alternative hypothesis is true.
Question 5: A renal dietitian finds a study on calcium supplementation in dialysis patients that was funded by a supplement manufacturer and reported only positive outcomes. Which type of bias is most likely present?
- Attrition bias
- Reporting and publication bias (Correct answer)
- Information bias
- Selection bias
Correct answer: Reporting and publication bias
Industry-funded studies and selective reporting of favorable outcomes are classic sources of reporting and publication bias, skewing the published literature.
Question 6: A dietitian wants to apply EBP to counsel a peritoneal dialysis patient on protein intake. After identifying a systematic review, appraising it, and finding strong evidence, the next step in the EBP process is:
- Search for more studies to confirm the finding
- Apply the evidence in the context of clinical expertise and patient values (Correct answer)
- Conduct a new RCT before making a recommendation
- Present the finding to the research team for approval
Correct answer: Apply the evidence in the context of clinical expertise and patient values
EBP integrates the best available evidence with clinical expertise and individual patient preferences and values before application.
Question 7: In a renal nutrition RCT, 20% of participants in the intervention group withdrew due to dietary intolerance. This differential dropout could result in which type of bias?
- Detection bias
- Performance bias
- Attrition bias (Correct answer)
- Reporting bias
Correct answer: Attrition bias
Attrition bias occurs when differential or systematic loss of participants from study groups distorts the comparison of outcomes.
CSR Research Methods & Evidence-Based Practice 3
A renal dietitian conducts a literature search and finds 12 relevant RCTs on protein intake and GFR decline.
To determine which studies to include in a systematic review, she uses predefined inclusion and exclusion criteria.
This step is best described as: