TYPES OF STUDIES IN DIABETES EPIDEMIOLOGY

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TYPES OF STUDIES IN DIABETES EPIDEMIOLOGY
Nam-Ham Cho, Ajou University
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TYPES OF STUDIES BASED ON

• Purpose
• Time
• Cost
• Feasibility

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TYPES OF STUDY

• Observational
• Descriptive
• Analytical
• Cross-sectional
• Retrospective
• Prospective
• Experimental
• Clinical Trial
• Community Intervention Trial
• Field Trial

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A STUDY DESIGN FOR THE OUTCOMES OF DIABETES

• Diabetes
• Morbidity (Complications)
• Mortality (Death)
• Economics
• Treatment
• Education
• Prevention Control
• Intervention

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TIME AND TYPES OF STUDY
PAST
FUTURE
PRESENT
Retrospective
Prospective
Cross-sectional
Time
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CROSS-SECTIONAL STUDY
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ANALYTICAL STUDY

• A cross-sectional study
• Privides a snap shot
• Is simple
• Provides associated factor
• Is first line of epidemiologic research

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CROSS-SECTIONAL STUDY

• What is different about
• DM
• Morbidity (Complications)
• Mortality (Death)
• How is it different about
• SES
• Age at onset
• Season

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CROSS-SECTIONAL STUDY
Incidence /100,000
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RETROSPECTIVE STUDY
Determining differences in

• Life style
• Diet
• Reproductive on
• Medication
• Family Hx
• Genetics

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RETROSPECTIVE STUDY PROS CONS
PRO
CON

• Suitable for rare diseases
• Inexpensive
• Minimal ethical problems
• Short study time
• Small of subjects
• Subjects need not volunteer

• Susceptable to selection memory bias
• Inconsistency definitions of symptoms or
  diseases may have been modified over time.
• Can not determine incidence
• Limitations in data
• Relative risk approximation

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PROSPECTIVE STUDY
PRESENT DM
Risk factors???
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PROSPECTIVE STUDY PROS CONS
PRO
CON

• Consistent disease definitions symptoms.
• Longer time
• Common disease only
• Expensive
• Ethical concern
• A high drop-out rate
• Volunteers needed
• A large of subjects needed
• The Hawthorne-effect

• Less variability to bias
• No recall necessary
• Incidence determined
• Relative risk accurate

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TYPES OF STUDIES AND GOALS
Prevention-Control-Intervention-Education-Manageme
nt
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EXPERIMENTAL STUDY

• Animal
• Drug trials
• Human

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EXPERIMENTAL STUDY
Randomized Clinical TrialDPP
Random Selection
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EXPERIMENTAL STUDY
Cross-over design
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Review Questions (Developed by the Supercourse
team)

• What are the advantages and disadvantages for
  retrospective studies?
• What are the advantages and disadvantages for
  prospective studies?