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

Appeared in: NORCET 10 Mains

Explanation

A Relative Risk (RR) of 1.0 means the incidence of the outcome is identical in both the exposed and unexposed groups.
This equality of risk signifies that there is no statistical association, either positive or negative, between the exposure and the disease.
The exposure is considered neutral; it neither increases nor decreases the risk of developing the disease.

Option A: This describes a scenario where the exposure is protective, which would result in a Relative Risk (RR) value of less than 1.0.
Option B: This describes a positive association, where the exposure increases the risk of the disease, corresponding to an RR value greater than 1.0.
Option D: Relative risk measures the strength of an association, but it does not prove causation. Proving causation requires fulfilling other criteria (e.g., Bradford Hill criteria).

Visual 1: Infographic - A simple chart illustrating the three interpretations of Relative Risk (RR less than 1, RR = 1, RR greater than 1) with icons representing protective, neutral, and risk-increasing effects.

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 reading research articles must correctly interpret RR to evaluate evidence for clinical practice. Misinterpreting an RR of 1.0 could lead to wrongly assuming a treatment or exposure is beneficial or harmful.
This concept is fundamental for evidence-based practice, helping nurses critique research studies on risk factors for diseases like hypertension, diabetes, or hospital-acquired infections.
What if? If the RR was 3.0, the nurse would understand this as a strong positive association, meaning the exposed group has three times the risk. This would warrant advising patients to avoid the exposure if possible.

How to Approach the Question

Identify the core concept: The question asks for the meaning of a specific Relative Risk (RR) value.
Recall the definition of RR: It's the ratio of incidence in the exposed group to the incidence in the unexposed group.
Analyze the given value (RR = 1.0): If the ratio is 1, the numerator (exposed risk) and the denominator (unexposed risk) must be equal.
Interpret the equality: Equal risk means the exposure has no effect on the outcome. This translates to 'no association'.
Evaluate the options based on this interpretation, eliminating those for RR greater than 1 (positive association), RR less than 1 (protective), and the incorrect assumption of causation.

Concept Tested & Keywords

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