In
epidemiology
Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population.
It is a cornerstone of public health, and shapes policy decisions and evidenc ...
and
biostatistics
Biostatistics (also known as biometry) are the development and application of statistical methods to a wide range of topics in biology. It encompasses the design of biological experiments, the collection and analysis of data from those experime ...
, the experimental event rate (EER) is a measure of how often a particular statistical event (such as response to a drug,
adverse event
An adverse event (AE) is any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An adverse event can ther ...
or death) occurs within the experimental group (non-control group) of an experiment.
This value is very useful in determining the therapeutic benefit or risk to patients in experimental groups, in comparison to patients in
placebo
A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures.
In general ...
or traditionally treated control groups.
Three statistical terms rely on EER for their calculation:
absolute risk reduction,
relative risk reduction
In epidemiology, the relative risk reduction (RRR) or efficacy is the relative decrease in the risk
In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with ...
and
number needed to treat
The number needed to treat (NNT) or number needed to treat for an additional beneficial outcome (NNTB) is an epidemiological measure used in communicating the effectiveness of a health-care intervention, typically a treatment with medication. The ...
.
Control event rate
The ''control event rate (CER)'' is identical to the experimental event rate except that is measured within the
scientific control group of an experiment.
Worked example
In a trial of hypothetical drug "X" where we are measuring event "Z", we have two groups. Our control group (25 people) is given a
placebo
A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures.
In general ...
, and the experimental group (25 people) is given drug "X".
Event "Z" in control group : 4 in 25 people
Control event rate In epidemiology and biostatistics, the experimental event rate (EER) is a measure of how often a particular statistical event (such as response to a drug, adverse event or death) occurs within the experimental group (non-control group) of an experi ...
: 4/25
Event "Z" in experimental group : 12 in 25 people
Experimental event rate : 12/25
Another worked example is as follows:
See also
*
Absolute risk reduction
*
Relative risk reduction
In epidemiology, the relative risk reduction (RRR) or efficacy is the relative decrease in the risk
In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with ...
*
Number needed to treat
The number needed to treat (NNT) or number needed to treat for an additional beneficial outcome (NNTB) is an epidemiological measure used in communicating the effectiveness of a health-care intervention, typically a treatment with medication. The ...
References
Biostatistics
Epidemiology
Medical statistics
Statistical ratios
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