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Summary placebo
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Summary of the lecture about placebo effects in clinical trials.
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PlaceboPlacebo = latin for I shall please
Nocebo = I shall harm
70 years ago -> placebo’s in different colours, informed consent not needed
Placebo = any dummy medication or treatment
-> placebos are medicinal preparations having no pharmacological activity against a targeted
condition used to administer control groups in clinical trials to provide baseline measurements
green light when there is a clinical significance between
placebo and medicine -> you get a medicine
Single blind, double blind -> to be effectively blind -> randomization controlled trial
Placebo effect
Placebo effect
-> effect (beneficial/not beneficial) caused by the expectations about a therapeutical intervention
-> Total effect to what happens in the placebo group
Placebo respons or perceived placebo effect = the total change in the placebo arm of a clinical
experiment is much more than the pure placebo effect
Notes about placebo effect:
Placebo in research:
There is no placebo effect in unconscious patients
Measure a placebo effect:reduce the background noise of a clinical trial make a control group
placebo effect = part of the therapeutic response of any therapeutic intervention
placebo effects are cognitive, behavioral or biological reactions to the contextual aspects of a
treatment
70 years ago -> an informed consent was not needed
The Lancet (1954) -> the humble humbug
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, Blind testing
Double blind = necessary to reduce bias
in an RCT ‘blind’ investigators evaluate patients different than the non-blind investigator
blind lab-experiments (counting cells under a microscope) is also better in a blind way
The powerfull placebo
-> injecting another substance than anesthesia when there was no more
anestheticum -> the placebo helped because the patient did not know that he did
not get the anestheticum
-> H. Beecher claimed that the total drug effect = its active effect + its placebo
effect this is not correct
-> placebo had to be powerfull to make RCT acceptable
History
In the past: everything was placebo
1945-1955: from decoy to powerful
1997: many details of the Beecher study were sloppy scholarship
2001: is placebo powerless -> analysis of clinical trials where doing nothing, placebo and medicine
were compared
-> conclusions:
they found little evidence that placebo had powerful clinical effects
the placebos had no significant effects on the object outcomes and they had possible small
benefits in studies with continuous subjective outcomes and for the treatment of pain
the discussion did not stop: RCTs are designed to test an intervention and not to learn something
about the placebo effect
Today: the placebo is again powerfull due to the work of Benedetti
If you do stuff in a hidden way you get a different result
-> hidden: pain keeps increasing
-> open: pain reduces
Wanneer je een electrode aan/af zet zonder aan de patient
te zeggen dat je deze aan/af zet -> je kan de impact meten
wanneer je zegt ik ga de knop induwen terwijl je deze niet
gaat induwen en vica versa
How long does a placebo work?
Depends on the study -> can be short lived or it may be persistent for weeks/days
-> when the participant of the study becomes aware that he/she receives a placebo -> the placebo
effect may diminish
Bv. Placebo in osteoarthrosis -> works for a long time
Effect size of a placebo depends on the type of the intervention -> acupuncture has the best placebo
effect
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