The relative risk of a disease can be obtained from:

ESIC Nursing Officer -2019 (Shift -1)

Nursing Research & Statistics

Easy

Appeared in: ESIC Nursing Officer -2019 (Shift -1)

Explanation

Relative Risk (RR) compares the incidence of a disease in an exposed group to the incidence in a non-exposed group.
Cohort studies are observational studies that follow groups forward in time (prospectively) from exposure to outcome.
This forward-looking design allows for the direct calculation of incidence rates in both the exposed and non-exposed cohorts, which is necessary to determine relative risk.
A well-designed cohort study is considered a reliable method for establishing an association between a risk factor and a disease.

Option A: While experimental studies (like RCTs) can calculate relative risk, they are interventional, not observational. In questions about standard epidemiological designs for observing risk, cohort studies are the more precise answer.
Option B: Case-control studies work backward from the disease (effect) to the suspected cause (exposure). They cannot measure incidence directly, so they calculate the Odds Ratio (OR), not the Relative Risk.
Option C: A case study is a descriptive report on a single patient or a small group. It lacks a comparison (control) group, making it impossible to calculate any measure of association like relative risk.

Visual 1: Flowchart - A diagram illustrating the difference in design between a cohort study (starts with exposure, follows for disease) and a case-control study (starts with disease, looks back for exposure).
Visual 2: Infographic - A simple 2x2 table showing the calculation of Relative Risk (Incidence in Exposed / Incidence in Non-Exposed) versus the Odds Ratio (Odds of exposure in cases / Odds of exposure in controls).

Clinical Relevance

Nursing practice connection: Knowing Measures of association in epidemiological study designs helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding relative risk is crucial for nurses to provide effective patient education. It allows them to explain the likelihood of developing a condition based on specific risk factors (e.g., 'Smokers are 20 times more likely to get lung cancer').
This knowledge empowers nurses to advocate for public health policies and preventive measures by quantifying the impact of harmful exposures.
What if the disease being studied is extremely rare? In that case, a cohort study would be impractical and inefficient, requiring a massive sample size and long follow-up. A case-control study would be the more feasible design, and the resulting Odds Ratio would serve as a good estimate of the Relative Risk.

How to Approach the Question

First, identify the key term in the question: 'relative risk'.
Recall the definition of relative risk: a measure comparing the probability of an outcome in an exposed group to a non-exposed group.
Review the definitions of the four study designs provided in the options.
Match the measure (relative risk) with the study design that allows for its direct calculation. A cohort study follows groups forward in time, measuring the incidence of disease, which is required to calculate relative risk.
Eliminate other options by recalling what they measure: case-control studies measure Odds Ratio, and case studies are descriptive with no risk calculation.

Concept Tested & Keywords

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