Experimental epidemiology 2nd b sc Nursing Methods of epidemiology Part -2

1. Experimental Epidemiology
By, Mrs Jinchu Paul
Nursing faculty

2. Randomized Control
Trial
Maj Dr Naveen
Phuyal MBBS,
MD

3. EXPERIMENTAL EPIDEMIOLOGY
This type of studies involve some intervention or
manipulation such as deliberate application or
withdrawal of suspected cause or changing one
variable in the causative chain in the experimental
group while making no change in the control group.
• Outcome of the experiment is compared in both the
groups.
• They may be conducted in animals or humans.
• Involves consideration of cost, ethics and feasibility

4. Aims of experimental studies
• To provide scientific proof of etiological
factors which may permit modification or
control of disease.
• To provide a method of measuring the
effectiveness and efficiency of health
services for the prevention, control and
treatment of disease and improve the
health of the community.

5. How does it differ from cohort
studies?
• The conditions in which the studies are carried
out are under direct control of the investigator.
• Involves some action, intervention or
manipulation such as deliberate application or
withdrawal in an experimental group and a
control group
• Observes and compares the outcome
of experiment in both groups

6. Experimental Studies
ANIMAL STUDIES HUMAN EXPERIMENTS

7. Animal Studies
• Animals have played
important role in
men’s quest for
knowledge about
himself.
• Animal studies have
contributed to all
branches of
medicine.
Application
• To confirm etiological
hypothesis and study
pathogenic
phenomena
• Testing efficacy of
preventive and
therapeutic measures
such as vaccines or
drugs
• Completing the
natural history of
disease

8. Animal Studies
Advantage
• Can be bred easily
• Multiply rapidly
• Genetic experiments
Disadvantage
• Not all human disease can
be reproduced in animals
• All conclusions drawn may
not strictly apply to humans

9. Human Experiments
• Human experiments will always be
needed to investigate disease etiology
and evaluate the preventive and
therapeutic measures.

10. Types of experimental studies
1. Clinical (therapeutic) trial- patient suffering
from disease
2. Field trial (preventive trial)- healthy
individuals in the community
3. Community intervention trial- cluster of
human beings
4. Health service evaluation trial
5. Risk factor trial
6. Cessation experiments

11. • Ethical, administrative and other reasons
for which RCT not possible
– Direct experimentation not possible : smoking
and Lung CA
– Some preventive measure can be only
be applicable to small groups in a
community ( flouridation)
– When disease frequency is low and natural
history is long ( Cervical Ca)
NON RANDOMIZED TRIALS

12. • Uncontrolled trials (trials with no comparison
groups). Eg. Pap smear test reduces mortality from
Cx CA
• Natural experiments
– cigerrete smoking: smokers vs non smokers
– Natural disasters, atomic bombings, mogrants , social
groups,
– “The Great Experiment”
• Before and after comparison studies (eg. James
Lind and scurvy)
– Using a control group
– Without a control group

13. Randomized control study
• It is really an epidemiologic experiment.
A randomized controlled trial (or randomized control
trial; RCT) is a type of scientific experiment (e.g. a
clinical trial) or intervention study (as opposed to
observational study) that aims to reduce certain
sources of bias when testing the effectiveness of new
treatments; this is accomplished by randomly allocating
.

14. Thank you