Question

A cohort study was conducted with drinkers and non-drinkers of green tea to study its effect ondiabetes mellitus. The risk ratio was found to be 0.84. Which of the following statements is correct?

• A. Green tea reduces the risk of diabetes
• B. Green tea increases the risk of diabetes
• C. Data insufficient to establish causal association
• D. The value (0.85) tends to be close to 41, hence there is no effect

Answer 1

The Correct Option is D

A cohort study compared the incidence of diabetes mellitus between drinkers and non-drinkers of green tea. The study calculated a risk ratio (RR) of 0.84 for developing diabetes among green tea drinkers compared to non-drinkers. To interpret this value, it's important to understand:

• Risk Ratio (RR): This measure compares the risk of a certain event (e.g., developing diabetes) between two groups. An RR of 1 indicates no difference in risk; less than 1 suggests a reduction in risk, while greater than 1 implies an increased risk.

Given the RR of 0.84: 

• Interpretation: An RR of 0.84 suggests a 16% reduction in risk (1 - 0.84 = 0.16 or 16%) of developing diabetes for green tea drinkers compared to non-drinkers.

Reviewing the options:

Option	Interpretation
Green tea reduces the risk of diabetes	Correct interpretation according to RR value
Green tea increases the risk of diabetes	Incorrect, as RR < 1
Data insufficient to establish causal association	Possibly true, but not directly linked to RR
The value (0.85) tends to be close to 41, hence there is no effect	Confusing and incorrect

The correct statement based on RR interpretation is: Green tea reduces the risk of diabetes, as indicated by the RR of 0.84, meaning it suggests a risk reduction not an increase or lack of effect.