clinical trials - course guide Flashcards
what is a clinical trial
planned experiment
in humans
measure effectiveness of an intervention
usually a new drug
can be surgical procedure, vaccine, complementary therapy
why are clinical trials unique
not observational
instead the researcher controls the situation
features of a clinical trial
experimental control group prospective - followed through time patients enrolled, treated and followed for the same amount of time participants should be randomised blind
what is a control group
don’t receive intervention
why do you need a control group
know that the outcome was because of the treatment
what is a control group given
placebo (sugar tablet/water injection)
or standard treatment
what is randomisation
people recruited, consent
randomly allocated to intervention or control
why randomise
remove allocation bias
w/o it is likely the researcher will choice different people for the groups
example of randomisation
in BCG vaccination trial - more compliant patients given vaccine, less compliant = control
more compliant would have better health measures anyway - so would have less chance of having TB anyway
what is blinding
patient doesn’t know if getting medication or placebo
double blind - dr doesn’t know
why double blind
prevent measurement bias
people on meds think they’re getting better, and drs look for more improvements
ethics of a clinical trial
patients consent and can withdraw at any stage
have to be registered
reviewed by independent scientific committee
approved by a research ethics committee
adhere to government and international guidelines
independent data monitoring committee - can check the progress of the trial, if large difference between groups they have the power to stop the trial
analysis of the clinical trial
outcomes presented in terms of efficacy - true biological effect of the treatment or effectiveness effect of treatment when actually used in practice
what is the experimental event rate
the incidence in the intervention arm
what is the control event rate
incidence in the control arm
relative risk =
EER/CER
relative reduction=
(CER-EER)/CER
absolute risk reduction=
CER-EER
number needed to treat
1/absolute risk reduction
reporting trial
reported according to the CONSORT guidelines
papers include relevant information for readers to critically appraise
phase 1
test safety
side effects
small number of people - healthy
phase 2
larger group 100 patients people have the disease see if effective in short term also look at safety
phase 3
treatment of larger group compare with placebo/treatment in use how well it works side effects several thousand patients located form different places smaller the expected advantage - more people needed to take part
phase 4
after the drug has been marketed
side effects of long term use
drug’s affect in various populations
