Relative Risk Reduction Formula (Table of Contents)
What is the Relative Risk Reduction Formula?
A risk is a measure of uncertainty. Relative risk reduction talks about an event as the likelihood of the happening after exposure to a risk variable when compared in light of the occurrence of the same event in a controlled or a reference group. The definition of risk reduction can alternatively be defined as the difference in the occurrence of an event when compared between two sets of groups which is expressed in contrast as the proportion of an untreated group. The set of groups taken in relative risk reduction often remains constant across the given set of a population with a different underlying set of risks. Therefore, the concept of relative risk reduction is more accurate and expressive when compared to the concept of absolute risk. Also, the lower the event rate in the control group, the larger the difference between relative risk reduction and absolute risk reduction.
The formula for Relative Risk Reduction –
When the event has a relative risk reduction of greater than 1, the risk of the outcome is then stated as an increase by the treatment. On the other hand, when the risk of treatment is lower than 1, the risk of a bad outcome has been decreased, meaning that the treatment conducted had a positive impact on the experimental group of people and individuals. A Relative Risk Reduction of 1 means that the risk of the event is identical in the exposed and the control samples.
Examples of Relative Risk Reduction Formula (With Excel Template)
Let’s take an example to understand the calculation in a better manner.
Relative Risk Reduction Formula – Example #1
FIC institute of medical research conducted an experiment for Control Event Rate Compared Treatment to a new Chemo drug which was recently launched. 70% of the control group died, and 35% of the experimental group died. Calculate the Relative Risk Reduction for the new chemo drug introduced.
Solution:
Relative Risk Reduction is calculated using the formula given below
Relative Risk Reduction (RRR) = (Control Event Rate (CER) – Experimental Event Rate (EER)) / Control Event Rate (CER)
 Relative Risk Reduction = (70% – 35%) / 70%
 Relative Risk Reduction = 50%
So the Relative Risk Reduction is 50%. The interpretation of this study is that The death rate in the experimental group is almost half of that of the controlled group. It tells you the reduction of medical intake in the experimental group, basically. Relative risk reduction is a convenient way of reexpressing a risk ratio as a percentage reduction.
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Relative Risk Reduction Formula – Example #2
Medical Institute of the United States of America conducted an experiment for Neuropathy. The experiment states that if 20% of the people die with the treatment of Neuropathy. And 15% die with treatment Control Event Rate then calculate the relative risk reduction.
Solution:
Relative Risk Reduction is calculated using the formula given below
Relative Risk Reduction (RRR) = (Control Event Rate (CER) – Experimental Event Rate (EER)) / Control Event Rate (CER)
 Relative Risk Reduction = (20% – 15%) / 20%
 Relative Risk Reduction = 25%
The risk of treatment is lower than 1, and the risk of a bad outcome has decreased. Hence the treatment of Neuropathy had a positive effect on the healing of the individuals.
Relative Risk Reduction Formula – Example #3
According to the DDT Data of the United Kingdom, 60% of the controlled group died of Chemotherapy, and 30% of the treated group died of the same. Therefore, calculate and interpret the Relative Risk Reduction of the above problem.
Solution:
Relative Risk Reduction is calculated using the formula given below
Relative Risk Reduction (RRR) = (Control Event Rate (CER) – Experimental Event Rate (EER)) / Control Event Rate (CER)
 Relative Risk Reduction = (60% – 30%) / 60%
 Relative Risk Reduction = 50%
It means that it has a positive effect on the experimental group.
Relevance and Uses
Risk measures have the advantage of being stable across populations with different baseline risks and are, for instance, useful when combining the results of different trials in a metaanalysis.
It is widely used in the medical industry to calculate the effect of the introduction of new medicines and medical practices, which in turn results in the betterment and improvement of the medical industry.
Relative Risk Reduction Formula Calculator
You can use the following Calculator
Control Event Rate (CER)  
Experimental Event Rate (EER)  
Relative Risk Reduction (RRR) Formula =  
Relative Risk Reduction (RRR) Formula = 


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This has been a guide to the Relative Risk Reduction formula. Here we discuss how to calculate Relative Risk Reduction along with practical examples. We also provide a calculator with a downloadable excel template. You may also look at the following articles to learn more –