Lectures 4-6 Flashcards
Proportions
Division of 2 related numbers
*Numerator is part of the denominator
Ratios
Division of 2 unrelated numbers
*Numerator not part of denominator
Rates
Division of 2 numbers with time incorporated into the denominator
What must be defined prior to answering the W’s of descriptive epidemiology?
Case Definition: must describe what it takes to be a “case” then decide if the issue at hand fits that description
Crude Morbidity Rate
of persons with Disease/# of persons in population
Crude Mortality Rate
of deaths (all causes)/# of persons in population
Cause-Specific Mortality Rate
of cause-specific deaths/# of persons in population
Case-Fatality Rate
of cause-specific deaths/# of cases of disease
Cause-Specific Survival Rate
of cause-specific cases alive/# of cases of disease
Live Birth Rate (per year)
of live births/1,000 population
Fertility Rate (per year)
of live births/1,000 women of childbearing age (15-44)
Infant-Mortality Rate (per year)
of deaths in those <1 year of age/1,000 live births
Proportional Mortality Ratio (PMR)
of cause-specific deaths/total # of deaths in population
Standardized Mortality Ratio (SMR)
of cause-specific deaths/expected total # of deaths from a similar population…equalized for gender, age, race, calendar time-frame, etc…
Infectivity
Ability to invade a patient (host) # infected/# susceptible (x100%)
Pathogenicity
Ability to cause disease # with clinical disease/# infected (x100%)
Virulence
Ability to cause death # of deaths/# infected (x100%)
Induction Period
Period required for a specific agent to produce a disease
Latency Period
Interval between infection and clinical appearance of disease
What are the 3 key factors in descriptive measures of disease frequency?
of people affected by disease
Size of the source population
Length of time the population is followed
Incidence
New cases of disease # of new cases (during a defined time period)/# persons at risk (during the same time period) *Subtract those who already have the disease or are immune to the disease
Prevalence
Existing cases of disease (includes old and new)
Incidence Rate
# new cases of disease (during defined time period)/person-time at risk of the disease (during same time period) *Subtract those individuals' time of observation who already have the disease or are immune
Incidence Density
# new cases of disease (during a defined period of time)/person-time (net/total) people were "at risk" for the disease Repeat Cases: Count first occurrence only
Point Prevalence
Prevalence at a given point in time
Period Prevalence
Prevalence over a given period of time
Epidemic
Occurrence of disease clearly in excess of normal expectancy
Community/period clearly defined
Outbreak
Epidemic limited to a localized increase in the occurrence of disease
*Sometimes called a cluster (but cluster is usually smaller)
Endemic
Constant presence of a disease within a given area in excess of normal levels in other areas
Pandemic
An epidemic occurring over very wide area, involving large number of people (often multi-regional/multi-national)
Primary Prevention
Protection of health by personal and communal efforts... Enhancing nutrition Immunizations Eliminating environmental risks EX: Vaccines
Secondary Prevention
Set of measures available to individuals and communities for early detection and prompt intervention to control disease…
Early disease, pre-clinical/clinical (known or not)
EX: Hypertension/HIV
Tertiary Prevention
Softening the impact of long-term disease by eliminating or reducing impairment, minimizing suffering, & maximizing potential years of useful life... Advanced disease (known) EX: Using dialysis for kidney issues
