Clinical Trials

Question 1

Clinical trial

Answer 1

Planned experiment in HUMANS, designed to measure effectiveness of an intervention

Question 2

How do clinical trials differ from observational studies?

Answer 2

Observational studies- investigator measures what happens but does not control it.
Clinical trial- investigator chooses who does what

Question 3

Features of a clinical trial

Answer 3

Experimental
Must contain a control group
Prospective
Participants randomised & followed over same period of time

Question 4

What must a clinical trial contain?

Answer 4

Control group

Question 5

Why must a clinical trial contain a control group?

Answer 5

If not included, you wouldn’t know why the change happened as too many variables

Question 6

Why randomise in a clinical trial?

Answer 6

Removes treatment allocation bias

Question 7

What is Blinding?

Answer 7

patient does not know whether they are getting the new treatment or not.

Question 8

What is double blinding?

Answer 8

neither patient nor doctor knows which treatment they are getting.

Question 9

Ethics in a clinical trial

Answer 9

Registered & reviewed by an independent scientific committee
Independent data monitoring committee
Patients provide informed consent & can withdraw at any time

Question 10

Experimental event rate (EER)

Answer 10

Incidence in the intervention arm

Question 11

EER Equation

Answer 11

𝐷𝑖𝑠𝑒𝑎𝑠𝑒 𝑒𝑣𝑒𝑛𝑡 / 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 𝑠𝑖𝑧𝑒 𝑜𝑓 𝑖𝑛𝑡𝑒𝑟𝑣𝑒𝑛𝑡𝑖𝑜𝑛 𝑔𝑟𝑜𝑢𝑝

Question 12

Control event rate (CER)

Answer 12

Incidence in the control arm

Question 13

CER Equation

Answer 13

𝐷𝑖𝑠𝑒𝑎𝑠𝑒 𝑒𝑣𝑒𝑛𝑡 / 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 𝑠𝑖𝑧𝑒 𝑜𝑓 𝑐𝑜𝑛𝑡𝑟𝑜𝑙 𝑔𝑟𝑜𝑢𝑝

Question 14

Relative risk equation

Answer 14

EER / CER

Question 15

Relative risk reduction equation

Answer 15

(CER- EER) / CER

Question 16

Relative risk reduction

Answer 16

% decrease of incidence between interventions compared to control

Question 17

Absolute risk reduction (ARR)

Answer 17

absolute reduction in incidence of disease between intervention & control.

Question 18

ARR Equation

Answer 18

CER- EER

Question 19

Number needed to treat (NNT)

Answer 19

Average number of patients who need to be treated to prevent 1 additional bad outcome
Inverse of ARR

Question 20

NNT Equation

Answer 20

1 / ARR

Question 21

What is the ideal NNT?

Answer 21

1 : where everyone improves with treatment & no one improves with control.

Question 22

The higher the NNT

Answer 22

The less effective is the treatment.

Question 23

Clinical trials are reported according to

Answer 23

CONSORT guidelines

Question 24

Clinical Trial Phase 1

Answer 24

Aims to test the safety & ensure there are no adverse side effects of a new treatment
Small No. of healthy humans

Question 25

Clinical Trial Phase 2

Answer 25

Tests whether new treatment is effective against illness it was designed for
Small sample of humans with relevant illness

Question 26

Clinical Trial Phase 3

Answer 26

Compare the new treatment with the treatment currently in use, or with a placebo. Look at how well the new treatment works, & at any side effects it may cause
Provides large sample size of analysable data
Large sample of humans with relevant illness

Question 27

Clinical Trial Phase 4

Answer 27

Trials are done after the drug or treatment has been marketed to gather information on the drug’s effect in various populations & any side effects associated with long-term use
Tests side effects when used alongside other common drugs