Epidemiology Study Design Quiz

Study Notes

Epidemiological studies investigate disease occurrence in populations.
Epidemiologists use carefully designed research strategies to explore disease causes.
Epidemiologists differ from clinicians or lab investigators by studying disease in the context of multiple factors impacting people's lives.

Descriptive studies examine the pattern of disease occurrence by person, place, time, and host, agent, and environment factors.
- Case reports and case series: individual or small group of patients with unusual features.
- Correlation studies: look for associations between exposures and disease in populations.
- Cross-sectional studies (Prevalence studies/Surveys): a snapshot of the prevalence of exposure or disease in a population at one point in time; measure exposure and disease status simultaneously.
Analytic studies: explore relationships between exposure and disease.
- Observational studies: do not involve intervention;
  - Case-control studies: start with people with disease and compare them to those without, looking for past exposures.
  - Cohort studies: start with a group of people with and without an exposure and follow them over time to compare disease incidence.
- Interventional (Experimental) studies: involve interventions or treatments to assess their effects on disease outcomes.

Utilize existing data, saving resources and time.
Identify disease patterns, allowing for analysis of the impact and development of preventive programs.
Identify risk factors, guiding further research.
Help identify populations at risk, enabling resource allocation.

Use aggregate measures of exposure and outcome from multiple populations to evaluate potential associations.
Population is the unit of observation.
Advantages: quick and easy, identify potential exposure-disease relationships.
Disadvantages: cannot link exposures to individuals, cannot control confounding factors.

Case Report: An individual case with an unusual clinical picture.
Case Series: Multiple cases with similar unusual findings.
Uses: generating hypotheses about disease causes, identifying new diseases or epidemics.

Advantages: Use available data, detailed individual data, suggest need for further investigation.
Disadvantages: may reflect the experience of a single person or clinician; lacking a comparison group.

Advantages: provides information on frequency, characteristics of the disease, standardized data collection tools, quick and repeatable.
Disadvantages: cannot determine the temporal relationship between exposure and disease, may be biased by incomplete participation, reflect prevalent cases rather than incident cases.