Medical research involves many epidemiology study scheme The study design is decided by The nature of the research question. Descriptive study,analytical study, exploratory study Clinical trial,cross sectional study,case control study (diseases and non disease group/ ) cohorte study (exposed and non exposed)

1. 1
EPIDEMIOLOGY STUDY DESIGN
Dr ADEGBITE Roméo
Centre de recherche médicale de Lambaréné
(CERMEL) 2017

2. OUTLINE
• Definition and Classification of studies
• Study Designs and analysis
• Choice of study design
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3. DEFINITION
• Epidemiology is the study of
the distribution and determinants of health-
related states or events in specified
populations, and the application of this study
to the control of health problems
• Various Epidemiology study schemes
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4. CLASSIFICATION
EPIDEMIOLOGY STUDY SCHEMES
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NON-
INTERVENTIONAL
(Researcher do not manipulate
situations/objects)
INTERVENTIONAL
(Researcher manipulates
situations/objects)
Exploratory
Descriptive
Analytical
Experimental (Classical
experiment)

5. Study designs
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NON-INTERVENTIONAL STUDY
Exploratory Study
Gathers information about
unfamiliar phenomenon
Results gives insight to a
problem before a large scale
study is designed
Descriptive study
Only describe
phenomenon
(Frequency)
Cross-sectional descriptive
investigation (picture)
Longitudinal investigation
(take a long time)
Analytical study
Describe phenomena
And Analyze relationship
between phenomena and
other variables
Cross-sectional
comparative
Cohort study
Case-control study

6. Study designs
Cross-sectional analytical study
• Done at one point in time
• The Measurement of exposure and effect are
done at the same time
• Aim to describe the phenomenon and
compare groups or determine factors
influencing the phenomenon
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7. Design of Cohort study
• Aims to determine the risk factors for diseases/outcome
• Time
• Inquiry
• **
** Exposed and non-exposed groups
must be comparable in all factors
except for the exposure
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Population Non-diseased
people
Exposed
Non-exposed
No disease
Disease
Disease
No disease
Start
ENDEND
Compare
incidences of
disease among
exposed to
non-exposed
group in
purpose to
determine the
risk factor with
statistic
analysis tool

8. Case – control studies
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9. Design of Case-control study
• Also Aim to determine the risk factors for diseases/outcome
• Time
• Inquiry
• medical history
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Non expose
Exposed
Non exposed
Exposed
Population
Cases( diseases
Group)
Controls
Non-disease
group
Start
At the endAt the end,
analyse
exposures
to a risk
factor in
both
groups and
compare
with
statistic
tool

10. Intervention studies
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11. Study designs
EPIDEMIOLOGY STUDY SCHEME
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NON-
INTERVENTIONAL
INTERVENTIONAL
(Researcher manipulates
situations/objects)
Experimental Study

12. intervention study
Characteristics of Experimental studies
– Manipulation
• Something is done to the two groups
– Presence of Control group and experimental
group
– Randomization (assignment of individuals to
experimental or control groups is done randomly)
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13. Design of Randomized controlled trial -
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General pop
Study
PX Randomization
Exp. group
Control group
Placebo group
Follow up &
Analysis
blin
ding
ENDEND
Compare the outcome of interest in experimental and control
groups and baseline characteristics in the both groups

14. CHOICE STUDY
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15. Choosing a study design
Considerations:
• Ethical issues – minimal ethical concerns
• Resources and administrative issues
• Validity and reliability of results
• Nature of topic
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16. Ethical Considerations in all studies
• Epidemiology study is Carried out only if:
– Evidence suggest intervention is beneficial, but
uncertain of effect
– No serious adverse events to the intervention
group
– Participant was Informed and given consent to
participate
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17. conclusion
• Various epidemiology study scheme
• The study design is decided by The nature of
the research question
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