NORCET 10 Mains: In a cohort study, the relative risk (RR) is 1.0. This indicates:

NORCET 10 Mains

Nursing Research & Statistics

Easy

Appeared in: NORCET 10 Mains

Explanation

In epidemiology, Relative Risk (RR) compares the risk of a health event (like a disease) in an exposed group to the risk in an unexposed group.
An RR of 1.0 means the incidence of the disease is identical in both the exposed and unexposed groups, as the ratio of the two risks is 1.
Therefore, a value of 1.0 signifies that there is no statistical association between the exposure and the disease; the exposure neither increases nor decreases the risk.

Option A: This describes a negative association or a protective effect, where the exposure reduces the likelihood of the outcome.
Option B: This describes a positive association, where the exposure increases the likelihood of the outcome.
Option D: This statement confuses association with causation. Epidemiological measures like RR can show a strong statistical link, but they cannot, by themselves, prove that the exposure is the definitive cause. Other factors, known as confounders, might be responsible for the outcome.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Interpretation of Relative Risk (RR) in cohort studies as background academic context rather than a clinical decision trigger.
Nurses use their understanding of RR to critically appraise research studies and apply evidence-based practice, for instance, when evaluating the effectiveness of a new intervention or the risk associated with a certain lifestyle factor.
This knowledge is crucial for patient education, allowing nurses to explain risks and benefits of treatments or lifestyle changes in an understandable way (e.g., explaining why smoking cessation is recommended based on studies showing a high RR for lung cancer).
What if the RR was 0.5? In that case, the exposure would be considered a protective factor, reducing the risk of the disease by 50% in the exposed group compared to the unexposed group.

How to Approach the Question

First, identify the core concepts in the question: 'cohort study', 'relative risk (RR)', and the specific value '1.0'.
Recall the definition of Relative Risk: it's a ratio of the incidence of an outcome in an exposed group to the incidence in an unexposed group.
Think about what a ratio of 1.0 means mathematically. If the numerator (risk in exposed) and the denominator (risk in unexposed) are the same, the ratio is 1.
This equality implies there is no difference in risk between the two groups, hence no association.
Evaluate the options based on this understanding: an RR of 1.0 matches 'no association', while values greater than 1 indicate positive association (increased risk) and values less than 1 indicate negative association (protective effect).

Concept Tested & Keywords

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 71-73