In some experiments, placebo control is used. These types of experiments can be both controversial, such as when participants are deprived of the opportunity for an existing effective treatment, and relatively unproblematic, such as when calcium tablets are given to the placebo group in addition to the standard treatment. In the following, you can read more about what placebo is, why it is used, and what scientific ethical pitfalls exist when placebo is used in an experiment.

What is a placebo?

A placebo is an inactive treatment. That is, a treatment that resembles the experimental treatment but does not contain the active part. It can be, for example, injections that only contain saline, but also things like medical devices designed not to have an effect, and sham surgical procedures, count as a variant of placebo. Therefore, placebo treatment can take many different forms, and there can also be very different risks associated with different types of placebo treatment.

Why is placebo control used?

Placebo treatment is used primarily to ensure that there are as few differences as possible between the participants who receive and do not receive the experimental treatment. This is particularly important regarding placebo, as receiving a new treatment, which one has positive expectations towards, can have an effect on participants, even if the treatment has no effect in itself (a placebo effect). By giving the control group a placebo treatment, one can thus even out the noise that otherwise might sneak into the experiment's results through the placebo effect.

What should be considered?

When placebo treatment is given in an experiment, it is worth noting whether participants are withheld or deprived of an existing effective treatment. In such cases, the use of placebo requires special justification. There must thus be a good scientific reason to use placebo, and participants must not be exposed to serious or irreparable harm as a result of receiving placebo treatment (see the note to the left of the page for more details). Additionally, it is worth paying attention to whether it is possible for participants to discover that they have received placebo treatment. If, for example, there are side effects associated with the treatment that are very noticeable to participants, such as a rash on the skin, some participants may possibly figure out that they have been assigned to one treatment or another. In such cases, it might be a good idea for the applicant to subsequently ask participants which group they believe they were in to check the quality of blinding. Finally, it is worth noting whether there are special risks or burdens associated with the placebo treatment that should be communicated to participants. It could be, for example, risks of allergic reactions due to dyes or similar. Such risks can often be overlooked in the communication of risks, which often limits itself to the experimental treatment and any investigative procedures.

Last updated 01-02-2024
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