3: Morbidity & Mortality Flashcards
Count
Simplest and most frequently used quantitative measure. Refers to number of cases of a disease or other health phenomenon being studied. Significant for rare diseases or symptom presentations.
Ratio
value obtained by dividing one quantity by another. Includes proportions, rates, and percentages. x/y, where x and y are independent factors
Proportion
States a count relative to the size of the group. x is contained in y. typically expressed as a percentage. can demonstrate the magnitude of a problem
Rate
A ratio that consists of a numerator and denominator in which time forms part of the denominator. Contains disease frequency, unit size of population, and time period during which an event occurs.
Prevalence
Number of existing cases of a disease or health condition in a population at some designated time. Provides an indication of the extent of a health problem.
Uses of Prevalence
- Describing the burden of a health problem in a population.
- Estimating the frequency of an exposure.
- Determining allocation of health resources such as facilities and personnel.
- DOES NOT GIVE RISK!!
Point Prevalence
ill at point in time/total # in group at point in time
Point Prevalence
ill at point in time/total # in group at point in time
Period Prevalence
ill during time period/average population during time period
Incidence
Number of new cases of a disease that occur in a group during a certain time period
Incidence Rate (Cumulative Incidence)
Describes the rate of development of a disease in a group over a certain time period.
Uses of Incidence Rate
- Help in research on etiology
- Estimate risk of developing a disease
- Estimate effects of exposure to a hypothesized factor of interst
Incidence Rate
new cases over time period/total population at risk over time period
Attack Rate (AR)
Alternative form of incidence rate. used for disease observed in a population for a short time period, usually infectious. Not a true rate because time dimension often uncertain. Can be used to find source of attack. AR= ill/ill+well x 100 (during a time period)
Attack Rate (AR)
Alternative form of incidence rate. used for disease observed in a population for a short time period, usually infectious. Not a true rate because time dimension often uncertain. Can be used to find source of attack. AR= ill/ill+well x 100 (during a time period)
Incidence Density
Incidence measure used when members of a population or study group are under observation for different lengths of time. Incidence Density=new cases during time period/total person-time of observation.
Interrelationship between Prevalence and Incidence
Prevalence is proportional to incidence rate x duration of disease
Interrelationship between Prevalence and Incidence
Prevalence is proportional to incidence rate x duration of disease
Crude Birth Rate
Used to project population changes; affected by number and age composition of women of childbearing age. Crude Birth Rate=live births/population size x 1,000