Epidemiological Terms and Measures Flashcards
Lecture Objectives
discuss the practical importance of epidemiology, define descriptive and analytic epidemiology, identify the measures of disease frequency and measures of association, review the distributions of key forms of visual impairment in the US, differentiate between levels of disease in a population
T/F disease is evenly distributed in the population
false
Epidemiology
the study of the distribution of health-related states or events in specified populations and the application of this study to control health problems
What does epidemiology help us figure out?
who is at risk and why
Study
observing, recording, experimenting
Distribution
who, when, where
Determinants
why, how
health-related states
moves beyond the study of diseases
What is descriptive epidemiology?
pattern recognition; who, when, where
What does descriptive epidemiology generate?
measures of disease frequency
Rate
counting health events over time
Risk
likelihood of developing a disease
T/F descriptive epidemiology can be used to test hypotheses
false; can only generate hypotheses not test because there is no comparison group
What are general measures of disease frequency?
incidence rate, cumulative incidence aka cumulative risk, prevalence rate
What is the most fundamental measure of disease incidence?
incidence rate
What is incidence rate?
number of new cases per person-time of observation
What is person-time?
the amount of at-risk time each person contributes to the rate
What is the incidence rate equation?
new cases/ (person-time at risk)
What is cumulative incidence/risk?
risk of acquiring the disease within a defined period of time
What is the cumulative incidence/risk equation?
new cases/ total population at risk
T/F the longer the time period, the higher the cumulative incidence
true
T/F cumulative incidence/risk is given as a percentage
true
What is prevalence rate?
proportion of total cases in a population at one point in time
What is the prevalence rate equation?
P= incidence rate x average duration of disease
What is prevalence rate used for?
can be used for administration, planning, some research
If incidence rate goes up or survival time is long, prevalence is
high
If incidence is high but duration is short, prevalence is
relatively low
Refractive error trends:
myopia>hyperopia, presbyopia very high, 1/3 Americans have astigmatism, 1/2 of US adults have <20/20 acuity due to a refractive error
Leading cause of blindness in African Americans
glaucoma
T/F AMD will decrease as population ages
false, it will increase
T/F DM Retinopathy will increase as population gets older and fatter
true
How does high prevalence help people plan for the future?
invest in OCT, telemedicine, fundus camera
How many individuals permanently lose all or part of their vision due to injury each year?
50,000 70% under 25 years
What are common causes of eye injury?
fireworks, DIY projects, sports and recreation, job related
What are the most common pediatric sports and recreation-related eye injuries?
K abrasion, conjunctivitis, foreign body
What are the top sports for eye injuries?
basketball, softball and baseball, non-powder guns
Analytic epidemiology
search for causes/factors that influence health-related events
What are comparing groups for?
key factor to test hypotheses, generate measures of association between exposure and outcomes
What are comparing groups?
demographics, genetic or immunologic make-up, behaviors, environmental exposure, other risk factors
What may determinants and analytic epidemiology lead to?
early intervention and recommended prevention measures
Absolute risk
risk of a health event happening over a certain time period
AR equation
AR= # of health events in a population/ total populations at risk
Relative risk
risk of experiencing a health event based on group membership
RR equation
RR= risk of population B/risk of population A; population A is usually lower incidence risk
If RR=1, risk or prevalence is
equal between populations
If RR >1, risk is
higher in population B
Why is relative risk useful in a clinical setting?
it helps us assess patients for disease
Relative risk, risk ratio, and odds ratios, provide a measure of the…
strength of the association between a factor and a disease or outcome
Risk difference, or absolute risk, provides a measure of the…
public health impact of the risk factor and focusses on the number of cases that could potentially be prevented by eliminating the risk factor
Epidemiology of disease helps predict what groups will account for the majority of cases, but the prevalence rates give us more of an idea of who is going to be at…
a higher risk among the population with a disease
What is health?
a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity
Morbidity
reported cases of disease, illness, disability; current health status of a population; predictive of future health problems and mortality rates
Mortality
number of deaths in a population
Progression of the study of disease
communicable, communicable and non, chronic diseases, health and well being
Population
any group affected by a particular disease or disorder ex: zip code, city, state, nation occupation, ethnic group, social class
Application
provides data for directing public health action
Remember 3 core functions of public health
assessment and monitoring, formulating public policies, assurance
Sporadic
occasional, irregular occurrence
What are sporadic diseases?
likely due to some natural reservoir or host for the causative organism; acanthamoeba, food-borne disease, cruezfeld-jakob disease
What are endemic diseases?
disease frequency is maintained without external inputs; cataracts, refractive error, common cold
What is epidemic?
sudden increase in cases above endemic/baseline level; 1.645 standard deviations above the baseline of P&I deaths
What is common source epidemic?
not transmissible; ex: chlorine gas leak
What is propagated epidemic?
transmissible; infectious disease ex: EKC, norovirus, HIV, Ebola, COVID
Example of non-infectious, long lasting epidemic
obesity
What is pandemic?
epidemic affecting a wide area
Can level of disease in a population change?
yes, sporadic becomes epidemic becomes pandemic OR epidemic becomes endemic
