Epidemiology Flashcards
Incidence
The number of NEW cases of a disease occurring during a specified period of time.
Prevalence
Number of individuals with a given disease (current cases) divided by the total number of individuals in the defined population. (proportion of the population with the disease). Given as a percentage or # cases/100,000.
Point Prevalence
Proportion of individuals within a define population with a given disease at a SINGLE point in time. (Jan 1, 2018)
Period Prevalence
Proportion of individuals within a defined population who have a given disease within a specified period of time. (example, annual prevalence rate).
Lifetime prevalence
Proportion of individuals in a defined population who have, have had, or will have a given disease at any time in their lives.
Incidence rate:
Number of new cases of a disease occurring during a specified period of time DIVIDED by the defined population at the start of that time interval.
If period prevalence rate is higher than incidence rate, what does that mean? Lower?
Disease lasts longer than the specified period. Chronic disease. If lower, the disease on average lasts shorter than the specified period.
Experimental Studies
Involve trials that expse at least some study subjects to a factor or agent and assess its role in the PREVENTION or TREATMENT of a particular disease.
Different from observational studies which are natural such that subjects sorted themselves into groups.
Observational studies
These are the ones used in epidemiology. ‘Natural experiments.’ Look at exposures in NATURAL SETTINGS that can lead to disease states .
Cohort Study
Epidemiological study in which a group of healthy people are studied that share a common characteristic. ‘What will happen to me? “ study.
Which study do you use to study the association between exposure to risk factors and disease development?
Cohort Prospective Study. It minimizes the weaknesses of retrospective studies which rely on recall.
Case-Control Study
Retrospective study in which subjects with a disease or condition are compared against controls , who are people that are as similar as possible to the cases with the single difference being that the control does not have the disease.
Benefits of Case-Control
Fast: identify 2 groups and compare their past exposures.
- Cheap
- good for rare diseases
- initial study that can lead to prospective (better) or experimental studies.
Weakness: confounding variables can be present.
What is a confound?
Variable that is not equally distributed among case and control groups. Confounds weaken the ability to interpret study results.
Cross-sectional study
“Am I Like My Neighbors” Study. Simultaneously examines current exposures and health status in a group or groups.
- Has an assumption that current expsorues have been present for a long time and have had time to effect health outcomes.
What did the Epidemiological Catchment Area (ECA) Study tell us ?
Told us about the prevalence rate of psychiatric disorders in 1980, DSM III. 5 site study.
What to know about the National Comorbidity Survey (NCS)?
Estimated prevalence of DSM-III-R, US sample of 10,000 individuals from 1990-1992.