placebo, bias and trail design Flashcards
the placebo effect vs the nocebo effect?
the placebo effect- no active compound but the patient is told their symptoms will improve so the patient believes they feel like their symptoms have improved.
nocebo effect- again there is no active ingredient but the patient is told their symptoms will get worse, so after receiving the nocebo they believe their symptoms have worsened.
what 2 reasons explain the placebo response?
either the condition has actually gotten better naturally,
or
there is a psychobiological phenomenon where the placebo has tricked the mind.
what are the 5 placebo phenomenons?
2 pills will have a greater effect than 1?
larger pills have a greater effect than 1.
injections are more effective than pills,
doctors wearing a white lab coat gives a better effect than a doctor in a t-shirt
if there is verbal encouragement from a doctors the treatment will work better.
what is pre-conditioning?
if you give the drug with a drink,
then give the drink with a placebo,
you can see some of the positive effects of the drug.
an example of nocebo?
chemotherapy; anticipating the nausea.
why do patients get an analgesic effect when taking a placebo?
activation of opioid receptors
what is conformation bias?
this is when you remember when a treatment worked, and seem to not remember when the treatment doesn’t work. so you have more of a positive view of the treatment than deserved.
what is feedback bias?
you only review a drug or report on the drug when it works.
what is meta analysis?
combining and comparing many different clinical trials to identify common trends caused by the drug
what is a systematic review?
using explicit, systematic methods to minimise bias
what is publication bias and how does it affect systematic bias?
it is when the outcome of the experiment/research determines whether the conductors distribute the results.
so the systematic review fail to find eligible study as not all information is available.
what are some things to consider when designing a clinical trial?
using placebos? randomised cohort? crossover in cohort? number of volunteers? how are patients selected? what outcomes are measured? how is data analysed? how is bias eliminated and how is the placebo effect controlled?
