PRINCIPLES OF EPIDEMIOLOGY EXAM
QUESTIONS WITH COMPLETE
SOLUTIONS
Prevalence proportion (prevalence) - ANSWER--measure of existing disease in a
population at a particular time
-period prevalence: during a period
-point prevalence: at one point in time
Crude rate (overall rate) - ANSWER--one giving the total number of events occurring in
an entire population over a period of time, w/o reference to any of the individuals or
subgroups within the population
Crude Rate Example - ANSWER--Surgeon A: 500 surgeries/year, 40 SSIs/year
-Crude rate 40/500= 8%
-Surgeon B: 400 surgeries/year, 50 SSIs/year
-Crude rate 50/400= 12.5%
Adjusted rate - ANSWER--fictitious summary rate statistically adjusted to remove the
effect of a variable, such as age or sex, to permit unbiased comparison between groups
having different compositions w/ respect to these variables
Attack Rate - ANSWER--another measure of morbidity
-often used in infectious disease investigations
-the proportion of persons who are exposed to an agent and develop the disease
-SARS attack rates in excess of 50% have been reported
Case Fatality Rate - ANSWER--another measure of mortality
-proportion of persons diagnosed with a particular disorder that die within a specified
period of time
-SARDS case fatality rate: total deaths/total cases (812/8,439)
Endemic - ANSWER--Constant presence of a disease or infectious agent within a given
geographic area or population group
Epidemic - ANSWER--outbreak due to exposure of a group of persons to a noxious
influence that is common to the individuals in the group
Pandemic - ANSWER--an epidemic occurring worldwide (or very wide area), crossing
international boundaries, usually affecting a large number of people
Epidemiologic Triangle - ANSWER--agent
-host
, -environment
-developed to identify causative factors, transmission, and risk related to infectious
disease
Agent - ANSWER--infectious agent (bacteria)
-chemical agent (pesticides)
-physical agent (radiation)
Host - ANSWER--genetic susceptibility
-immutable characteristics (age)
-acquired characteristics (immunological status)
-lifestyle factors (diet, exercise)
Environment - ANSWER--climate (temperature)
-plant and animal life (reservoirs for agents)
-human population distribution (crowding)
-socioeconomic factors (education)
-working conditions (level of stress)
Web of Causality - ANSWER--reflects the more complex interrelationships among the
numerous factors interacting to increase (or decrease) risk of disease
-associations are sometimes mutual, with lines of causality going in both directions
Ecological Model - ANSWER--expands epidemiologic studies
-upward to broader contexts (e.g. social context)
-downward to the genetic and molecular level
Primary Prevention - ANSWER--interventions aimed at preventing the occurrence of
disease, injury, or disability
-individuals who are susceptible to disease
Primary Prevention Broad Efforts - ANSWER--health promotion: nutrition educations,
promotion of physical activity
-environmental protection: basic sanitation, food safety
-specific protection: immunization, proper use of seat belts
-occurs in homes, community settings, primary level of health care
-major focus: health education
-reduction of risk factors before occurrence of disease, condition, or injury
Secondary Prevention - ANSWER--interventions designed to increase the probability
that a person w/ a disease will have that condition diagnosed at a stage when treatment
is likely to result in cure
-health screenings
-early + periodic screenings
-pts who want to prevent further complications or exacerbations
-screening of persons who have had contact with individual known to have disease
QUESTIONS WITH COMPLETE
SOLUTIONS
Prevalence proportion (prevalence) - ANSWER--measure of existing disease in a
population at a particular time
-period prevalence: during a period
-point prevalence: at one point in time
Crude rate (overall rate) - ANSWER--one giving the total number of events occurring in
an entire population over a period of time, w/o reference to any of the individuals or
subgroups within the population
Crude Rate Example - ANSWER--Surgeon A: 500 surgeries/year, 40 SSIs/year
-Crude rate 40/500= 8%
-Surgeon B: 400 surgeries/year, 50 SSIs/year
-Crude rate 50/400= 12.5%
Adjusted rate - ANSWER--fictitious summary rate statistically adjusted to remove the
effect of a variable, such as age or sex, to permit unbiased comparison between groups
having different compositions w/ respect to these variables
Attack Rate - ANSWER--another measure of morbidity
-often used in infectious disease investigations
-the proportion of persons who are exposed to an agent and develop the disease
-SARS attack rates in excess of 50% have been reported
Case Fatality Rate - ANSWER--another measure of mortality
-proportion of persons diagnosed with a particular disorder that die within a specified
period of time
-SARDS case fatality rate: total deaths/total cases (812/8,439)
Endemic - ANSWER--Constant presence of a disease or infectious agent within a given
geographic area or population group
Epidemic - ANSWER--outbreak due to exposure of a group of persons to a noxious
influence that is common to the individuals in the group
Pandemic - ANSWER--an epidemic occurring worldwide (or very wide area), crossing
international boundaries, usually affecting a large number of people
Epidemiologic Triangle - ANSWER--agent
-host
, -environment
-developed to identify causative factors, transmission, and risk related to infectious
disease
Agent - ANSWER--infectious agent (bacteria)
-chemical agent (pesticides)
-physical agent (radiation)
Host - ANSWER--genetic susceptibility
-immutable characteristics (age)
-acquired characteristics (immunological status)
-lifestyle factors (diet, exercise)
Environment - ANSWER--climate (temperature)
-plant and animal life (reservoirs for agents)
-human population distribution (crowding)
-socioeconomic factors (education)
-working conditions (level of stress)
Web of Causality - ANSWER--reflects the more complex interrelationships among the
numerous factors interacting to increase (or decrease) risk of disease
-associations are sometimes mutual, with lines of causality going in both directions
Ecological Model - ANSWER--expands epidemiologic studies
-upward to broader contexts (e.g. social context)
-downward to the genetic and molecular level
Primary Prevention - ANSWER--interventions aimed at preventing the occurrence of
disease, injury, or disability
-individuals who are susceptible to disease
Primary Prevention Broad Efforts - ANSWER--health promotion: nutrition educations,
promotion of physical activity
-environmental protection: basic sanitation, food safety
-specific protection: immunization, proper use of seat belts
-occurs in homes, community settings, primary level of health care
-major focus: health education
-reduction of risk factors before occurrence of disease, condition, or injury
Secondary Prevention - ANSWER--interventions designed to increase the probability
that a person w/ a disease will have that condition diagnosed at a stage when treatment
is likely to result in cure
-health screenings
-early + periodic screenings
-pts who want to prevent further complications or exacerbations
-screening of persons who have had contact with individual known to have disease
