OCC Evidence-Based Medicine & Research Flashcards

Which type of study provides the highest level of evidence in evidence-based medicine hierarchy?

Answer: Systematic review and meta-analysis of randomized controlled trials

Systematic reviews and meta-analyses pooling data from multiple high-quality RCTs sit at the top of the evidence hierarchy.

In a randomized controlled trial (RCT), what is the purpose of blinding participants and investigators?

Answer: To reduce performance and detection bias

Blinding prevents performance bias (participants changing behavior) and detection bias (investigators interpreting outcomes differently) when they know the treatment assignment.

A study reports a relative risk (RR) of 0.6 for a new drug compared to placebo for MI. What does this mean?

Answer: The drug reduces MI risk by 40% relative to placebo

RR of 0.6 means the treated group has 60% of the risk of the control group — a 40% relative risk reduction.

What is the number needed to treat (NNT) if the absolute risk reduction (ARR) of a treatment is 5%?

Answer: 20

NNT = 1/ARR = 1/0.05 = 20, meaning 20 patients need to be treated for 1 additional patient to benefit.

In a diagnostic test evaluation, a test with high sensitivity is best used for which purpose?

Answer: Screening (ruling out disease when negative)

A highly sensitive test has few false negatives — a negative result effectively rules out disease (SnNout: Sensitive test, Negative result = rule Out).

Which statistical measure describes the probability that a patient without the disease will test negative on a diagnostic test?

Answer: Specificity

Specificity = true negatives / (true negatives + false positives) — it is the probability that a disease-free person tests negative.