Evidence Application - Eppp Skills

1. Which option best indicates likely publication bias in a meta-analysis: symmetric or asymmetric funnel plot?

   Asymmetric funnel plot. Asymmetry in funnel plots suggests small studies with non-significant results are missing, indicating bias toward positive findings.

2. What is the formula for number needed to treat (NNT) using absolute risk reduction?

   $NNT = \frac{1}{ARR}$. NNT translates ARR into the number of patients needed for one additional benefit, facilitating clinical interpretation.

3. What is internal validity in treatment research?

   Confidence that the intervention caused the outcome. It assesses whether study design and controls allow attributing observed effects directly to the treatment.

4. What is a clinically meaningful outcome difference, as distinct from statistical significance?

   A change large enough to matter for functioning or well-being. It focuses on practical impact, ensuring changes improve patient quality of life beyond mere p-values.

5. Identify the RR when $CER = 0.20$ and $EER = 0.10$.

   $RR = 0.5$. Dividing EER by CER yields 0.5, indicating halved risk in the experimental group.

6. What is evidence-based practice (EBP) defined as in clinical decision-making?

   Integration of best research, clinical expertise, and patient values. This definition, from Sackett et al., ensures balanced, informed decisions by combining empirical evidence with professional judgment and individual preferences.

7. Which study design is most efficient for studying rare outcomes using prior exposure status?

   Case-control study. Matching cases with rare outcomes to controls and retrospectively assessing exposures efficiently identifies associations.

8. Which option indicates a statistically significant mean difference at $\alpha = 0.05$: CI $(-0.2, 1.1)$ or CI $(0.3, 1.1)$?

   CI $(0.3, 1.1)$. For mean differences, significance at 0.05 occurs if the CI excludes zero, as in the selected interval.

9. Which evidence source is typically strongest for summarizing treatment effects across studies?

   Systematic review with meta-analysis. It synthesizes multiple studies, increasing precision and power to estimate overall effects reliably.

10. What does PICO stand for when translating a clinical need into a research question?

    Patient/Problem, Intervention, Comparison, Outcome. PICO framework structures clinical questions to facilitate targeted evidence searches and precise application to patient care.

11. What is an intention-to-treat analysis in an RCT?

    Analyze participants in assigned groups regardless of adherence. ITT preserves randomization benefits and provides pragmatic estimates of treatment effects in real-world adherence scenarios.

12. What is the first step of the EBP process when a clinical question arises?

    Formulate an answerable clinical question (often PICO). Structuring the question clearly guides efficient literature searches and applicability of research to the specific clinical scenario.

13. What is the primary purpose of random assignment in an RCT?

    Reduce selection bias and balance confounders across groups. Randomization ensures groups are comparable at baseline, enhancing causal inference by controlling known and unknown variables.

14. Which study design is best for estimating prevalence of a disorder at a single time point?

    Cross-sectional study. It captures data at one time, allowing estimation of how common a condition is in a population.

15. What is blinding (masking) intended to reduce in outcome assessment?

    Expectancy and measurement bias. Masking participants and assessors minimizes subjective influences on reported or measured results.

16. Which study design is best for estimating incidence and temporal ordering of risk factors?

    Prospective cohort study. Following participants forward establishes timelines between exposures and outcomes, aiding risk assessment.

17. Which study design provides the strongest evidence for treatment efficacy in most cases?

    Randomized controlled trial (RCT). RCTs minimize bias through randomization and control, providing robust causal evidence for intervention effectiveness.

18. What is the formula for absolute risk reduction (ARR) when applying trial results to patients?

    $ARR = CER - EER$. ARR quantifies absolute benefit by subtracting experimental from control event rates, aiding patient-specific decisions.

19. What does a $95\%$ confidence interval (CI) for a mean difference primarily communicate?

    A plausible range for the true effect size in the population. The 95% CI indicates values compatible with data, where exclusion of zero suggests statistical significance.

20. What is allocation concealment intended to prevent in randomized trials?

    Foreknowledge of assignment that could bias enrollment. It maintains randomization integrity by preventing selective participant inclusion based on group knowledge.

21. Which option indicates statistical significance for an odds ratio: CI $(0.8, 1.4)$ or CI $(1.2, 2.0)$?

    CI $(1.2, 2.0)$. For odds ratios, significance is indicated when the CI excludes 1, showing a likely non-null effect.

22. What is external validity in applying research findings to a specific patient?

    Generalizability of findings to the target patient/context. It evaluates how well study results apply to real-world patients and settings beyond the trial.

23. What is the formula for relative risk (RR) when comparing event rates across groups?

    $RR = \frac{EER}{CER}$. RR compares outcome probabilities between groups, providing a relative measure for evaluating intervention impact.

24. Identify the NNT when $CER = 0.30$ and $EER = 0.20$ for an undesirable outcome.

    $NNT = 10$. With ARR of 0.10 from the given rates, NNT calculates as its reciprocal for practical application.

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