MEASURES OF DISEASE FREQUENCY & MORBIDITY (PART 1) Flashcards
Number of events, such as disease, injury, death & etc.
Frequency
calculate measures of disease frequency:
1) Count of events
2) Population size
3) Period of observation
4) Constant, K
● Arbitrary multiplier of some power of 10 used to express and compare measures in similar population units
Constant, K
Method for calculating FREQUENCY:
(# of events in a specified period/ population at risk of the event during the specified time period) x K
● Division of one quantity by another.
RATIO
Comparison of any two values.
Includes any expression with a numerator and a denominator.
Ratio
The numerator and denominator can be related or unrelated to each other
True
T or F | Ratios can be used as descriptive
(male:female ratio)
(risk ratio, rate ratio, odds ratio)
Analytic tools
■ Commonly used epidemiologic ratio.
DEATH-TO-CASE RATIO
Number of deaths attributed to a particular disease during a specified period divided by number of new cases of that disease identified during the same period
DEATH-TO-CASE RATIO
Measure of severity of illness.
DEATH-TO-CASE RATIO
Method for calculating RATIO:
One group / Another group
● Type of ratio in which the numerator is contained in the denominator’s
PROPORTION
Tells us what fraction of the population is affected
PROPORTION
Expressed as a decimal, percentage, or fraction
Usually expressed in percentage
PROPORTION
Method for calculating PROPORTION:
of ___ with a particular characteristic / Total # of ___ which numerator is a subset
For a ________, 10” is usually 100 (or n= 2) and is often expressed as a percentage.
proportion
● Measure of the frequency with which an event occurs in a defined population over a specified period of time.
RATE
Describes how quickly disease occurs in a population.
RATE
● Proportion of persons who are unaffected at the beginning of a study period, but who experiences a risk event during the study period
RISKS
● Constitutes the people at risk for the event at the beginning of the study period
COHORT
is the number of persons counted at the beginning of the study.
Denominator
The ________ for the risk in a cohort study for several years does not change unless participants are lost to follow-up.
denominator
● The probability of an event that will occur (P) divided by the probability that the event will not occur (1-P)
ODDS
● State of being symptomatic or unhealthy for a disease/condition
MORBIDITY
Presence of disease in a population
Morbidity
Two categories of measurement to describe Morbidity Frequency of disease in a specified population:
○ Incidence (new cases)
○ Prevalence (existing cases-old & new)
● Occurence of new cases of events (disease, injury, death, etc.) in a population at risk over a specified period of time.
INCIDENCE/INCIDENT CASES
Number of transitions (well-ill, uninjured-injured, alive-dead).
INCIDENCE/INCIDENT CASES
Types of INCIDENCE/INCIDENT CASES
○ Incidence Proportion/Risk
○ Incidence Rate/Person-Time Rate
● The proportion of initially disease-free population that develop new cases of disease in a specified period of time.
INCIDENCE PROPORTION/RISK
Measures probability that healthy people will develop disease during a specified time.
INCIDENCE PROPORTION/RISK
○ Attack Rate
○ Incidence Risk
○ Probability of Developing Disease
○ Cumulative Incidence
INCIDENCE PROPORTION/RISK
