EPIDEMIOLOGICAL STUDIES: Descriptive Study Designs; Analytic Epidemiology Flashcards
- Describes
- More exploratory
- Profiles characteristics of groups
- Focuses on “what”
- Assumes no hypothesis
- No comparison between groups over time
DESCRIPTIVE
- Explains
- More explanatory
- Analyze why the group has characteristics
- Focuses on “why”
- Assumes hypothesis
- Comparison between groups
over time
ANALYTICAL
Study of:
- amount of occurrence of disease
- Its distribution within the population
- For the purpose of identifying non-random variation in disease occurrence
DESCRIPTIVE STUDY
- 1st step in risk factor determination
- Data lead to the formulation of research hypothesis
DESCRIPTIVE STUDY
Sources of data:
- Routinely collected
EXAMPLES: Census, vital registries, clinical records, employment health examination
DESCRIPTIVE STUDY
uses of DESCRIPTIVE STUDIES
- Trend Analysis
- Health Care Planning
- Hypothesis generation
types of DESCRIPTIVE STUDIES
- ECOLOGIC (correlational studies)
- CASE REPORT & CASE SERIES
- CROSS-SECTIONAL STUDIES (prevalence studies)
[TYPES OF DESCRIPTIVE STUDIES]
- Correlational or aggregate studies
- Measures the characteristics that represent the entire population
- Comparison of groups rather than individuals
- Describes disease in relation to a factor of interest
ECOLOGIC STUDIES
[TYPES OF DESCRIPTIVE STUDIES]
‘types of ECOLOGIC STUDIES’
- MULTI-GROUPED DESIGN
- TIME-TREND DESIGN (ecologic trend)
- MIXED DESIGN
[TYPES OF DESCRIPTIVE STUDIES]
‘types of ECOLOGIC STUDIES’
- compare rate of disease among DIFFERENT regions during SAME period search for SPATIAL PATTERN.
MULTI-GROUP DESIGN
[TYPES OF DESCRIPTIVE STUDIES]
‘types of ECOLOGIC STUDIES’
- compare the rate of disease OVER TIME in a GEOGRAPHICALLY DEFINED population
TIME-TREND DESIGN (ecologic trend)
[TYPES OF DESCRIPTIVE STUDIES]
‘types of ECOLOGIC STUDIES’
- show temporal trends, forecast future rate
and trends
MIXED DESIGN
[TYPES OF DESCRIPTIVE STUDIES]
Describes the experience of a single patient or group of patients with a similar diagnosis
CASE REPORTS & CASE SERIES
[TYPES OF DESCRIPTIVE STUDIES]
‘CASE REPORT & CASE SERIES’
- Document unusual medical occurrences
- Represents first clues in the identification of new diseases or adverse effects of exposures
- New syndromes or variants of known disease
CASE REPORT
[TYPES OF DESCRIPTIVE STUDIES]
‘CASE REPORT & CASE SERIES’
- collection of individual reports
- early means to identify the presence of an epidemic
- investigation of affected individuals can lead to hypothesis generation
- identification of the disease
- identification of specific risk factors
CASE SERIES
Objective:
- to test a hypothesis; a statement about the relationship between 2 variables
ANALYTIC STUDY
two types of ANALYTIC STUDY
- OBSERVATIONAL
- EXPERIMENTAL
EXPOSURE (E) and OUTCOME/ DISEASE (D)
variables are measured at one point in time or over a very short period of time
CROSS-SECTIONAL STUDY
- Provides information about the frequency and characteristics of the disease by furnishing a “snapshot” of the health experience of the population at a specified time
- Provides information on the prevalence of disease or other health outcomes
- Monitor changes in population over time
- Make inferences about the risk of developing a disease
- Determine the association between coexisting variables
CROSS-SECTIONAL STUDY
[CROSS-SECTIONAL DATA]
‘STEPS’
- ________ study population
- _______ an adequate # of ________ by scientific sampling techniques
- ________ data
- ________ data
- Choose
- Draw, subjects
- Collect
- Analyze
[CASE CONTROL STUDIES]
‘STEPS’
- ______ and ______ cases
- ________ and ________ of controls
- Ascertainment of _________
- _________
- Define, select
- Definition, selection
- exposure
- Analysis
[CASE CONTROL STUDIES]
‘Define and select cases’
- diagnostic criteria for the disease
- eligibility criteria
- may be problematic if the diagnostic procedure is expensive
ESTABLISH OBJECTIVE CRITERIA
[CASE CONTROL STUDIES]
‘Define and select cases’
sources:
- hospitals (secondary or case-defined base)
- population (primary study base)
- types: PREVALENT or INCIDENT cases
- methods of selection: total enumeration or random sampling
SELECT CASES
[CASE CONTROL STUDIES]
‘Definition and selection of controls’
- comparable to the source of population cases
- matching: to achieve comparability
- 1-1 matching
- category matching
DEFINITION CONTROL GROUP
[CASE CONTROL STUDIES]
“Definition and selection of controls”
- get controls from the same source population as the case
- SOURCE: hospital, general population, special groups
- METHODS: random sampling or paired sampling (matched)
SELECT CONTROL
[CASE CONTROL STUDIES]
- Operational definition of exposure variable
- SOURCES: subjects or medical records
- METHODS of data collection: same for the 2 groups
- Reference point should be identified: basis on which an individual should be considered exposed
ASCERTAINMENT OF EXPOSURE
[CASE CONTROL STUDIES]
- Measures of association
- Odds ratio (OR)
ANALYSIS
