Exam 3: Epidemiology Flashcards
characteristics of epidemiological studies
- study of chronic diseases, disabilities, health statuses
- chronic disease such as: AIDS, CV studies, COVID-19
what type of information is gathered in epidemiological studies?
- determining frequency of disease, health status, and trends
- determine factors that affect the development of a particular disease or health state and why
- predicting occurrence and distribution of various diseases and health status
- determining factors that prevent disease, prolong life w/disease, or improve health status
characteristics of observational descriptive epidemiological studies
when little is known about the occurrence or determinants of health conditions and disease states
- WHO experiences it
- WHERE is the frequency at its highest and its lowest
- WHEN does it occur the most/least
- sets priorities of health care planning to and to generate a hypotheses for analysis
characteristics of observational analytical epidemiological studies
- when enough is known about a condition to allow for testing of hypotheses about specific risk factors and disease
- use specific comparison groups; document temporal sequence (exposure level and when the individual developed disease)
- no interventions applied
two classifications of observational epidemiology
- descriptive observational
- analytical observational
classifications of descriptive observational epidemiological studies
- use: set priorities for health care planning
- generate hypotheses (analytic methods)
- case reports/case series
- correlational studies
- cross-sectional studies
case reports/case series for descriptive observational studies
- what is it: description of unique occurrence or medical condition
- purpose: complete description of characteristics/exposures; can hypothesize causal factors but cannot conclude
- limitations: not enough control bc it has already happened
- catalyst for further study
correlational studies of descriptive observational studies
- what is it: relationship of disease/disorder and specific exposure; analyze patterns in population without manipulating
- use: evidence to formulate hypotheses for testing
- adv: use information from big databases (CDC)
- limitations: no cause and effect relationship
ex: cig smokers developing CV disease
- inconclusive because there was “no proof”
cross-sectional studies in descriptive observational studies
- what is it: snapshot of population at one point in time
- purpose: describes the frequency of a disorder
- within defined group or population
- efficient method
- limitations: cannot determine causality of exposure and disease; insensitive to duration of disorder (long or short disease); under-representation of disease frequency due to death
measures of disease frequency
- looks at how it was measured: population size, period in time, whole numbers
- reflects risk for disease in a give group
- measured via prevalence and incidence
prevalence (measure of disease frequency)
existing # of cases divided by total population at specific time (not everyone in population has the condition)
- point prev: single point in time
- period prev: over 1 year
limitations of prevalence
- does not explain the cause
- long disease process means large prevalence
- short disease process means low prevalence even though there may be a lot of cases
- it is time dependent
incidence (measurement of disease frequency)
- amount of new cases in a specific time
- estimates his of developing disease during the time
- discounts effects of duration of illness
- 2 expressions: cumulative incidence and incidence rate
cumulative incidence
- number of new cases (given in a period of time) divided by the total population that is at risk
- CI: new cases/total population
incidence rate
- # of new cases/total person-time
- total person time: sum of time periods of observation (1 year or 28 years)
- can account for death/attrition
- more useful than cumulative incidence
