Measures of Disease Frequency Flashcards
Definition of Epidemiology
Determinants: origins or factors that cause ailment
and
Distribution: how the issue is presenting itself; where is the disease at?
John Snow
Father of epidemiology
Broadstreet Pump
Core Functions of Epidemiology
- Public Health surveillance
- Field Investigation
- Analytic Studies
- Evaluation
- Linkage
- Policy Creation
3 factors necessary to compare disease frequencies in different populations
Who (Person)
When (place)
Where (Time)
Case Definition
set of uniform criteria used to define a disease/condition for public health surveillance
Case Fatality Rate
# of cause-specific deaths -------------------------------------- # of cases of a certain disease
Cause-specific Mortality Rate
# of cause-specific deaths ----------------------------------------------- # of people in the population
Cause specific morbidity rate
# of cases of a certain disease -------------------------------------------------- # of people in a population
Cause-specific survival rate
# of cases that are alive -------------------------------------- # of cases of the disease
Cluster
an epidemic that is limited to a localized area (aka “outbreak”
Crude Morbidity Rate
# of cases of disease ------------------------------------ # of people in population
Crude Mortality Rate
# of all-cause deaths ------------------------------------ # of people in population
Cumulative Incidence
Incidence rate summed up over multiple periods of tim
Disease Registries
a database that is used to track the characteristics/prevalence/incidence of a disease
Endemic
A region where the baseline value of a disease is much higher when compared to other regions; usually the trend needs to be established for at least a year.
ex. AIDS in africa
Epidemic
any increase in disease or incidence that is clearly in excess (anything unusually high)
Fertility Rate
1,000 women of childbearing age in the population
Fixed populations
the # of people in the population doesn’t change
Dynamic populations
the # of people in the population changes
Frequency
not just the count of disease occurrences, but also the counts in relation to the size of the population being considered
NNDSS Incidence
National Notifiable Disease Surveillance System Incidence
Incidence Density
The sum of incidence rates from multiple time periods
this helps reflect the force of disease over time
Incidence Rate
# of new cases of illness --------------------------------------------- # of new people at risk
(aka attack rate)
ex. immune people must be subtracted from the denominator
Incubation Period
time between exposure and onset of disease
synonymous with “induction period”
Infant Mortality Rate
1,000 live births
Infectivity
The ability a disease has to infect people
# infected --------------------- # susceptible
Latency Period
Time between onset of the disease and the detection of the disease (symptoms or diagnosis)
Live Birth Rate
1,000 people in the population
Maternal Mortality Rate
100,000 live births
MMWR
Morbidity and Mortality Weekly Report
a scientific publication prepared by the CDC
Morbidity
# of people with a disease ------------------------------------------- # of people in the population
Mortality
# of total deaths ------------------------------------- # of people in the population
Neonatal Mortality Rate
1,000 live births
Outbreak
an epidemic that is limited to a localized population
synonymous with “cluster”
Pandemic
an epidemic that has reached a global scale and has a world-wide impact
Pathogenicity
describes the ability to cause clinical disease
# with clinical disease ------------------------------------- # infected
Virulence
synonomus with Case-fatality rate
# of cause specific deaths ---------------------------------------------- # with infectious disease
Period Prevalence
the prevalence over a given period of time (usually annual)
# of cases of a disease ----------------------------------------- # of people in a population
Person-Time
expresses a combination of the amount of people observed, and the length of time for which they were observed
ex. 100 years in person-time could mean 10 people followed for 10 years, or 100 people followed for 1 year
Postnatal Mortality Rate
1,000 live births
Prevalence
of people with a certain disease + the new cases of disease
# of people with a certain disease --------------------------------------------------------- # of people in a population
Prevalence Rate
# of people with a certain disease --------------------------------------------------------- # of people in a population
prevalence over a given period of time (usually annually)
Point Prevalence
the prevalence at an exact, specified time
# of people with a certain disease --------------------------------------------------------- # of people in a population
Population vs Sample
population is everyone in a designated demographic
Sample is the group that was used to conduct a study
Proportion
a simple part over whole percentage
a division of 2 related numbers
Proportional Mortality Rate
# of cause-specific deaths --------------------------------------------------- # of all deaths in a population
Rate
a proportion percentage with time incorporated into the denominator
Ratio
Division of 2 unrelated numbers
The denominator is not a part of the denominator, unlike proportions
Relative Differences
Compares the difference in 2 percentages
ex. relative difference between 1% and 2% is 100%
Risk
percentage of what could or could not occur
“think proportion when you hear risk”
Sentinel case
easily observable point on an epi graph that showcases the earliest outlier on the graph
synonymous with index case
cause-specific survival rate
# of cases that survived ------------------------------------------------- # of cases of the disease
Proportional Mortality rate
# of cause specific deaths --------------------------------------------------- # of total deaths (all causes)
Case-fatality Rate
# of cause specific deaths --------------------------------------------------------- # of cases
Syndromic surveillance
a system the looks for predetermined signs/symptoms of patients related to trackable-but-rare diseases
WHO
World Health Organization
