clinical trials - course guide

Question 1

what is a clinical trial

Answer 1

planned experiment
in humans
measure effectiveness of an intervention
usually a new drug
can be surgical procedure, vaccine, complementary therapy

Question 2

why are clinical trials unique

Answer 2

not observational

instead the researcher controls the situation

Question 3

features of a clinical trial

Answer 3

experimental 
control group 
prospective - followed through time 
patients enrolled, treated and followed for the same amount of time 
participants should be randomised 
blind

Question 4

what is a control group

Answer 4

don’t receive intervention

Question 5

why do you need a control group

Answer 5

know that the outcome was because of the treatment

Question 6

what is a control group given

Answer 6

placebo (sugar tablet/water injection)

or standard treatment

Question 7

what is randomisation

Answer 7

people recruited, consent

randomly allocated to intervention or control

Question 8

why randomise

Answer 8

remove allocation bias

w/o it is likely the researcher will choice different people for the groups

Question 9

example of randomisation

Answer 9

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

Question 10

what is blinding

Answer 10

patient doesn’t know if getting medication or placebo

double blind - dr doesn’t know

Question 11

why double blind

Answer 11

prevent measurement bias

people on meds think they’re getting better, and drs look for more improvements

Question 12

ethics of a clinical trial

Answer 12

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

Question 13

analysis of the clinical trial

Answer 13

outcomes presented in terms of efficacy - true biological effect of the treatment or effectiveness effect of treatment when actually used in practice

Question 14

what is the experimental event rate

Answer 14

the incidence in the intervention arm

Question 15

what is the control event rate

Answer 15

incidence in the control arm

Question 16

relative risk =

Answer 16

EER/CER

Question 17

relative reduction=

Answer 17

(CER-EER)/CER

Question 18

absolute risk reduction=

Answer 18

CER-EER

Question 19

number needed to treat

Answer 19

1/absolute risk reduction

Question 20

reporting trial

Answer 20

reported according to the CONSORT guidelines

papers include relevant information for readers to critically appraise

Question 21

phase 1

Answer 21

test safety
side effects
small number of people - healthy

Question 22

phase 2

Answer 22

larger group 
100 patients 
people have the disease 
see if effective in short term 
also look at safety

Question 23

phase 3

Answer 23

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

Question 24

phase 4

Answer 24

after the drug has been marketed
side effects of long term use
drug’s affect in various populations

Question 25

ACCOMPLISH hypertension treatment trial

Answer 25

RCT on patients with hypertension
comparing benazepril plus amlodipine (the intervention) to benazepril plus hydrochlorthiazide (the control).
primary end point was vascular event