RDN Research and Evidence-Based Practice 2 — Questions and Answers
Question 1: The PICO framework is used in evidence-based dietetics practice primarily to:
- Assess a patient's nutritional status at admission
- Formulate a focused, searchable clinical research question (Correct answer)
- Calculate estimated caloric requirements for hospitalized patients
- Evaluate food service operations and efficiency
Correct answer: Formulate a focused, searchable clinical research question
PICO (Population, Intervention, Comparison, Outcome) is a structured framework used to formulate focused clinical questions that guide systematic literature searches and evidence-based decisions.
Question 2: A dietary intervention reduces cardiovascular disease risk from 20% to 15%. The relative risk reduction (RRR) is:
- 5%
- 25% (Correct answer)
- 75%
- 15%
Correct answer: 25%
RRR = (control event rate − intervention event rate) ÷ control event rate = (20% − 15%) ÷ 20% = 25%.
Question 3: A number needed to treat (NNT) of 10 for a nutrition intervention means:
- 10 patients must be treated before one adverse event occurs
- 10 patients must receive the treatment for one additional patient to benefit compared to control (Correct answer)
- The treatment is effective in only 10% of patients
- 10 patients dropped out of the study before completion
Correct answer: 10 patients must receive the treatment for one additional patient to benefit compared to control
NNT is the number of patients who need to receive a treatment for one additional patient to benefit compared to those receiving the control, and is calculated as 1 ÷ absolute risk reduction.
Question 4: A confounding variable in a nutritional epidemiology study is BEST described as:
- The primary outcome variable being measured
- A variable associated with both the exposure and outcome that can distort the true relationship between them (Correct answer)
- A variable that has no relationship with the exposure or outcome
- The primary independent variable being studied
Correct answer: A variable associated with both the exposure and outcome that can distort the true relationship between them
A confounder is associated with both the exposure and the outcome; if not controlled for, it can create a spurious or masked association between the exposure and the outcome of interest.
Question 5: Intent-to-treat (ITT) analysis in a clinical nutrition trial analyzes data by:
- Including only participants who completed the full study protocol
- Including all randomized participants according to their original group assignment regardless of protocol adherence (Correct answer)
- Excluding participants who experienced adverse events during the trial
- Including only participants who fully adhered to the assigned dietary intervention
Correct answer: Including all randomized participants according to their original group assignment regardless of protocol adherence
ITT analysis includes all randomized participants in their originally assigned groups regardless of compliance, preserving the benefits of randomization and reflecting real-world effectiveness.
Question 6: A meta-analysis differs from a narrative systematic review primarily because a meta-analysis:
- Uses only qualitative summaries of evidence
- Requires no systematic literature search protocol
- Statistically combines quantitative results from multiple studies into a pooled estimate (Correct answer)
- Includes only observational studies rather than RCTs
Correct answer: Statistically combines quantitative results from multiple studies into a pooled estimate
A meta-analysis uses statistical methods to quantitatively pool and synthesize data from multiple studies, producing a single summary estimate, whereas a systematic review may include only narrative synthesis.
Question 7: In the evidence hierarchy used by the Academy of Nutrition and Dietetics, which type of evidence is placed at the LOWEST level?
- Randomized controlled trial
- Systematic review or meta-analysis
- Expert opinion, editorials, or anecdotal reports (Correct answer)
- Prospective cohort study
Correct answer: Expert opinion, editorials, or anecdotal reports
Expert opinion, editorials, and anecdotal evidence represent the lowest level of evidence because they are not based on systematic research methodology and are highly susceptible to individual bias.
RDN Research and Evidence-Based Practice 2
The PICO framework is used in evidence-based dietetics practice primarily to: