Evidence-Based Public Health Flashcards
Distribution
The component of epidemiology that describes who gets the disease, where people with the disease are located, and how these aspects of disease change over time.
Population
A group of people with a common characteristic in terms of person, place, and time.
Fixed Population
Membership in population is based on an event which is permanent.
Transient/dynamic
Membership in population is based on a condition that can change.
Mortality
Epidemiologic term for death.
Morbidity
Epidemiologic term for disease.
Crude Mortality Rate
Number of deaths from all causes
Age Specific Mortality Rate
Number of deaths from all causes in specific age group
Cause Specific Mortality Rate
Number of deaths from a specific cause
Infant
Number of deaths of infants less than 1 year of age
Disability
Umbrella term for impairments, activity limitations, and participation restrictions
Disease Frequency (How often does the MMD occur in the population?)
Quantification of MMD in the population
Disease Distribution (Who/where/changes in occurrence?)
Analysis of patterns
Epidemic
Outbreak or occurrence of a DDD from a single source, in a group, population, community, or geographical area, in excess of the usual level of expectancy
DDD
Death, Disease, Disability
MMD
Mortality Morbidity Disability
Endemic
The ongoing, usual level of, or constant presence of a DDD within a given population or geographic area
Pandemic
an epidemic that is widespread across a country, continent, or a large populace, possibly world wide (HIV)
Three Primary Measures of Association
Ratio, Proportion, Rate, Prevalence
Ratio
Division of one number by another, numbers don’t have to be related
Proportion
Numerator is subset of denominator, often expressed as a percentage
Rate
Time is an intrinsic part of denominator, term is most misused
Prevalence
Number of existing cases of disease / Number in total population (at a point or during a period of time)
Incidence
Number of new cases (1st occurrence) of disease that develop in a population at risk during a specified time period (time must pass to move from health to disease)
Cumulative Incidence (CI)
Number of new cases of diseases / Number of candidate population over a specified period of time
Estimates the probability or risk that a person will develop disease during a specified time
Mainly used for fixed populations
Candidate population
Comprised of people who are at risk of getting the disease
Incidence Rate (IR)
Number of new cases of disease in candidate population / person time of observation
A true rate because it directly integrates time into the denominator
What is it called when incidence decreases but people are living longer with the disease?
Increased prevalence
What is it called when incidence increases but the duration of living with the disease is short?
Decreased prevalence
What is it called when incidence decreases but the duration of living with the disease is short?
Decreased prevalence
RR
Relative Risk
Rate in exposed / Rate in unexposed
CI_exp / CI_unexp
Exposed w Disease / (Exposed w Disease + Exposed w No Disease)
/
Unexposed w Disease / (Unexposed w Disease + Unexposed w No Disease)
RR = 1.0
No association between exposure and disease
RR = 2.0
Two times the risk of disease in the exposed compared to the unexposed
RR = 1.6
1.6 times the risk of disease in the exposed compared to the unexposed or 60% increased risk of disease in the exposed. (1.60 - 1 = .6 = 60%)
Odds Ratio
The odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure.
Exposed with Disease / Exposed with No Disease
/
Unexposed with Disease / Unexposed with No Disease
What is most commonly used in case-control studies?
Odds ratio
What condition must be met in order for the OR to approximate the RR?
The disease must be rare
Which study design has the highest quality of evidence?
Systematic reviews
Which three study designs include filtered information?
Critically-appraised individual articles [articles synopses], Critically-appraised topics [evidence syntheses], and systematic reviews
Which three study designs include unfiltered information?
Case-controlled studies, Cohort studies, Randomized Controlled Trials (RCTs)
What are the four types of populations when designing a study? (From initial to end)
Target, Source, Eligible, Study
Ecological Fallacy
Making assumptions about the individual based on finding at the level of the population
Ecological Study
An observational study defined by the level at which data are analyzed, namely at the population or group level, rather than individual level.
Cross Sectional Study
A type of observational study, or descriptive research, that involves analyzing information about a population at a specific point in time. Typically, these studies are used to measure the prevalence of health outcomes and describe characteristics of a population
Population selected without regard to exposure or disease status
CANNOT determine cause and effect
Measure of association = OR
Point Prevalence
A particular point in time
Case-Control Study
Disease is rare
Disease has a long induction and latent period
Little is known about the disease
Selection of the cases
Selection of controls
Cohort Study
Two or more groups of people that are free of disease and that differ according to the extent of exposure (e.g., exposed and unexposed) are compared with respect to disease incidence
Cohort studies are the observational equivalent to experimental studies but the researcher cannot allocate exposure
What is the purpose, features, and setting of a Cohort Study?
Purpose: study causes, preventions, and treatments for diseases
Key Feature: investigator selects subjects according to their exposure levels and follows them for disease/outcome
Setting: trial not ethical, feasible, or too expensive. Little known about exposure so can evaluate many effects of an exposure. Exposure is rare.
Randomized Controlled Trials (RCT)
An experimental study that investigates the role of some “agent” in the prevention or treatment of disease
“agent” = treatment, screening program, intervention
The investigator “controls” the agent
It is because of this “control” that the RCT is considered the “gold standard”
Randomized Controlled Trials (RCT)
An experimental study that investigates the role of some “agent” in the prevention or treatment of disease
“agent” = treatment, screening program, intervention
The investigator “controls” the agent
It is because of this “control” that the RCT is considered the “gold standard”
How are RCT’s normally conducted?
- Hypothesis formed
- Study subjects recruited based on specific inclusion/exclusion criteria and their informed consent is sought
- Subjects are randomly allocated to receive one of the two or more interventions being compared
- Study groups are monitored for outcome under study (recurrence of disease, first occurence of disease, etc.)
- Rates of the outcomes in the various groups are compared
