13. Epidemiological studies – experimental studies

Question 1

What is an experimental study?

Answer 1

always an experimental and
control group. The investigator controls the exposure, often in
a randomized way.

Question 2

3. What are

intervention trials?

Answer 2

• An intervention trial is a follow-up experimental study in which the exposure under investigation is applied by the investigator.
• The aim of intervention trials is to investigate a possible causal relationship by exposing one or more groups of patients
  to a factor (treatment) and compare results to one or more control groups that are unexposed to this factor.
• In an intervention trial, the investigator decides which subjects are to be “exposed” and which not, so in epidemiology, intervention trials are the closest analogy of a
  laboratory experiment.

Question 3

Types of interventions:


Answer 3

Prophylactic - target on prevention (e.g. vaccines)

Diagnostic - target on evaluation of new diagnostic procedure
(e.g. new lab test to a gold standard, etc.)

Therapeutic - target on treatment (e.g. new drug)

Question 4

types of control groups

Answer 4

Placebo concurrent control group
Dose-response concurrent control group
Active concurrent control group
No treatment concurrent control group
Historical control 
(ask mahds to explain each one if needed)

Question 5

Intervention trials can be:

Answer 5

community trials
clinical trials
lab experimental trials

Question 6

Community trial

Answer 6

a research study, carried out in a realistic

community setting, that can involve an individual-leve

Question 7

clinical trials

Answer 7

– a research study to test new methods of

screening, prevention, diagnosis or treatment of a disease,carried out in hospital settings;

Question 8

lab experimental trials

Answer 8

a research study, usually carried out on animals or tissues in laboratories.

Question 9

What are clinical

trials?

Answer 9

Clinical trials can be randomized controlled studies or
nonrandomized studies (quasi-experiments).

Question 10

Randomized clinical trial (RCT)

Answer 10

is a prospective study that
estimates the effect of an intervention by comparing participant outcomes between randomly assigned treatment and control groups.

• RCT are the gold standard for development of new drugs.

Question 11

how many phases does Randomized clinical trials have

Answer 11

4

Question 12

phase 1

Answer 12

an early study to determine the non-toxic dose level in animals or small group of health volunteers.

Question 13

phase 2

Answer 13

• designed to assess the clinical efficacy of the therapy
  2a - assess dosing requirements
  2b - study efficacy

Question 14

phase 3

Answer 14

– designed to confirm the effectiveness, monitor side effects and compare to other treatments alternatives.

Question 15

phase 4

Answer 15

– designed to detect any rare or long-term adverse

effects over a much larger population and timescale.

Question 16

advantages of interventional trials

Answer 16

Provide strongest evidence for causality

Can investigate several outcomes from one exposure

Less susceptible to errors due to observer, subjectivity and technical issues

Question 17

Disadvantages of interventional trials

Answer 17

Costly and time consuming

Lost to follow-up cause selection bias

Ethical problems

Question 18

Single ascending dose studies :

Answer 18

: groups of several patients are given small doses and monitored for side effects. Ig no major side effects are present another set of groups are given a higher dose. This is continued until the side effects are intolerable. This is when the drug has reached maximum tolerated dose - MTD

Question 19

MULTIPLE ASCENDING DOSE STUDIES :

Answer 19

: group of patients receive a low dose and dose is subsequently escalated up to a predetermined level. Better example of pharmacokinetics and dynamics.

Question 20

Randomized

Answer 20

method of allocation of the patient to 2 or more treatment options where each patient has an equal chance of receiving each treatment.

Question 21

Blinding

Answer 21

• method to assure subject and investigator or outcome. Assessor is unaware of assignment.

Question 22

placebo def

Answer 22

pharmaceutical substance - no active ingredient.