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Difficulty: HardMeasures of Disease Frequency and Association

Match each clinical research scenario or calculated parameter to the specific epidemiological metric it best represents.

  • A randomized controlled trial compares a new anticoagulant to a placebo. The experimental group has a 4% rate of major gastrointestinal bleeding, while the placebo group has a 2% rate. The value 50 indicates the number of patients who must be treated to cause one additional major bleeding event.Number needed to harm (NNH)
  • A prospective cohort study follows 5,000 initially healthy adults for 10 years. During this time, 250 individuals are newly diagnosed with type 2 diabetes. The value of 5% represents the probability of developing the disease over the specified time period.Cumulative incidence
  • A state health department conducts a survey on a single day and finds that 50,000 out of 500,000 residents have a diagnosis of major depressive disorder. The value of 10% describes the burden of disease at that exact time.Point prevalence
  • Epidemiologists estimate that if radon gas exposure were eliminated from all homes, the total incidence of lung cancer in the general population would decrease by 15%. This percentage describes the proportion of disease incidence linked to this exposure.Population attributable risk percent (PAR%)
  • In a clinical trial for a novel biologic therapy, the risk of joint destruction is 12% in the treatment group and 16% in the placebo group. The value of 25% describes the proportional decrease in risk associated with the therapy.Relative risk reduction (RRR)

Answer

1 matches with Number needed to harm (NNH); 2 matches with Cumulative incidence; 3 matches with Point prevalence; 4 matches with Population attributable risk percent (PAR%); 5 matches with Relative risk reduction (RRR).
Each scenario uniquely outlines the mathematical calculation and clinical application of a specific epidemiological concept. Number Needed to Harm (NNH) measures the adverse impact of an intervention based on absolute risk increase. Cumulative incidence tracks new diagnoses within a defined timeframe. Point prevalence captures a statistical snapshot of existing cases. Population attributable risk percent (PAR%) measures the broad population-level impact of removing an exposure. Relative risk reduction (RRR) quantifies the proportional clinical benefit of an intervention compared to baseline risk.

Step-by-Step Solution

1
Evaluate the anticoagulant trial scenario.
Matches with Number needed to harm (NNH).
The scenario describes the calculation of the reciprocal of the absolute risk increase (4% - 2% = 2%; 1 / 0.02 = 50), which defines the NNH.
2
Evaluate the prospective cohort study scenario.
Matches with Cumulative incidence.
The scenario calculates the number of new cases developing over time divided by an initial at-risk population, which is the definition of cumulative incidence.
3
Evaluate the single-day survey scenario.
Matches with Point prevalence.
The scenario calculates existing cases over the total population at an exact point in time, measuring disease burden as point prevalence.
4
Evaluate the radon gas elimination scenario.
Matches with Population attributable risk percent (PAR%).
The scenario describes the percentage of total incidence in the general population that can be attributed to and potentially prevented by eliminating a specific exposure.
5
Evaluate the biologic therapy trial scenario.
Matches with Relative risk reduction (RRR).
The scenario calculates the proportional reduction in adverse outcomes relative to the control group risk ((16% - 12%) / 16% = 25%).

Key Concept

Measures of Disease Frequency and Association
Estimated Time:2m 0s
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Topics

Measures of Disease Frequency and Association

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