FINALS: MEASURES OF DISEASE FREQUENCY AND MORBIDITY Flashcards
Number of diseases, injury, death, and etc.
Frequency
Compare one part of distribution to another part of the distribution or to entire population
Frequency
are used to describe how common an illness (or other health event) is with reference to the size of the population (the population at risk) and a measure of time
MEASURES OF DISEASE FREQUENCY
Numerator
Count of events
Denominator
Population size
Disease
Morbidity
Death
Mortality
Birth
Natality
Epidemiologic Measures Categorized as
Ratio, Proportion, or Rate
Frequently Used Measures of Morbidity
Incidence proportion (or attack rate or risk)
Secondary attack rate
Incidence rate (or person-time rate)
Point prevalence
Period prevalence
Number of cases of a particular health event
Count
Examples:
□ Number of college students who smoke
□ Vehicular fatalities in Davao City during a 24-hour period
Count
Division of one quantity by another
Ratio
Includes any expression with a numerator and a denominator (general term)
Ratio
Examples:
□ Community X has:
■ 600,000 males: 400,000 females
■ 600:400 or 3:2
Ratio
A ratio in which the numerator is contained in the denominator
Proportion
RATIO
• Can be used as _________ (male: female ratio).
descriptive
RATIO as _________ (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
Tells us what fraction of the population is affected
Proportion
Proportion may be expressed as
Expressed as a percentage, decimal, or fraction
A ratio representing change over time
Rate
Describes how quickly disease occurs in a population
Rate
Can be expressed as a percentage or per unit time
Rate
X and Y can be any number, including ratios.
Ratio (R)
Type of ratio where the numerator is usually a count, and the denominator is a time elapsed.
Rate (r)
Type of ratio where the numerator is part of the denominator.
Proportion (p)
A proportion is multiplied by 100.
Percent (P)
• 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
The probability of an event that will occur (P) divided by the probability that the event will not occur (1-P)
Odds
Refers to the presence of disease in a population
Morbidity
Two categories of measurement to describe frequency of disease in a specified population
Incidence and prevalence
new cases
Incidence
existing cases – old and new
Prevalence
2 measure of incidence
Incidence Proportion
Incidence Rate
2 measured of prevalence
Point Prevalence
Period Prevalence
• State of being symptomatic or unhealthy for a disease / condition.
• Presence of disease in a population
MORBIDITY