Chapter 3: Measures of Morbidity and Mortality

Question 1

Adjusted rate

Answer 1

The rate of morbidity or mortality in a population in which statistical procedures have been applied to permit fair comparisons across populations by removing the effect of differences in the composition of various populations; an example is age adjustment.

Question 2

Age-specific rate

Answer 2

Frequency of a disease in a particular age stratum divided by the total number of persons within that age stratum during a time period.

Question 3

Attack rate

Answer 3

An alternative form of the incidence rate that is used when the nature of a disease or condition is such that a population is observed for a short time period. The attack rate is calculated by the formula ill/(ill 1 well) × 100 (during a time period). The attack rate is not a true rate because the time dimension is often uncertain.

Question 4

Cause-specific rate

Answer 4

Measure that refers to mortality (or frequency of a given disease) divided by the population size at the midpoint of a time period times a multiplier.

Question 5

Count

Answer 5

Total number of cases of a disease or other health phenomenon being studied.

Question 6

Crude birth rate

Answer 6

Number of live births during a specified period of time per the resident population during the midpoint of the time period (expressed as rate per 1,000).

Question 7

Crude rate

Answer 7

A summary rate based on the actual number of events in a population over a given time period. An example is the crude death rate, which approximates the proportion of the population that dies during a time period of interest.

Question 8

Cumulative incidence (cumulative incidence rate)

Answer 8

Number or proportion of a population (or group of people) who become diseased or develop a condition being studied during a stated period of time; used to calculate risk.

Question 9

Fetal death rate

Answer 9

Number of fetal deaths after 20 weeks or more gestation divided by the number of live births plus fetal deaths after 20 weeks or more gestation during a year (expressed as rate per 1,000 live births plus fetal deaths).

Question 10

Fetal death ratio

Answer 10

Number of fetal deaths after a gestation of 20 weeks or more divided by the number of live births during a year (expressed as rate per 1,000 live births).

Question 11

General fertility rate

Answer 11

Number of live births reported in an area during a given time interval divided by the number of women aged 15 to 44 years in that area (expressed as rate per 1,000 women aged 15 to 44).

Question 12

Incidence density

Answer 12

Number of new cases of disease during a time period divided by the total person-time of observation; used to calculate incidence when subjects have been observed for varying periods of time.

Question 13

Incidence rate

Answer 13

(Number of new cases of a disease—or other condition—in a population divided by the total population at risk over a time period) times a multiplier (e.g., 100,000).

Question 14

Infant mortality rate

Answer 14

Number of infant deaths among infants aged 0 to 365 days during a year divided by the number of live births during the same year (expressed as the rate per 1,000 live births).

Question 15

Maternal mortality rate

Answer 15

(Number of maternal deaths ascribed to childbirth divided by the number of live births) times 100,000 live births during a year.

Question 16

Measures of natality

Answer 16

Statistics associated with births.

Question 17

Neonatal mortality rate

Answer 17

Number of infant deaths under 28 days of age divided by the number of live births during a year.

Question 18

Perinatal mortality rate

Answer 18

Number of late fetal deaths after 28 weeks or more gestation plus infant deaths within 7 days of birth divided by the number of live births plus the number of late fetal deaths during a year (expressed as rate per 1,000 live births and fetal deaths).

Question 19

Perinatal mortality ratio

Answer 19

Number of late fetal deaths after 28 weeks or more gestation plus infant deaths within 7 days of birth divided by the number of live births during a year (expressed as rate per 1,000 live births).

Question 20

Period prevalence

Answer 20

Number of cases of illness during a time period divided by the average size of the population.

Question 21

Point prevalence

Answer 21

Number of cases of illness in a group or population at a point in time divided by the total number of persons in that group or population.

Question 22

Postneonatal mortality rate

Answer 22

Number of infant deaths from 28 days to 365 days after birth divided by the number of live births minus neonatal deaths during a year (expressed as rate per 1,000 live births).

Question 23

Prevalence

Answer 23

Number of existing cases of a disease or health condition in a population at some designated time.

Question 24

Proportion

Answer 24

Fraction in which the numerator is a part of the denominator.

Question 25

Proportional mortality ratio (PMR)

Answer 25

Number of deaths within a population due to a specific disease or cause divided by the total number of deaths in the population during a time period such as a year.

Question 26

Rate

Answer 26

A ratio that consists of a numerator and denominator in which time forms part of the denominator. Example: The crude death rate refers to the number of deaths in a given year divided by the size of the reference population (during the midpoint of the year) (expressed as rate per 100,000).

Question 27

Ratio

Answer 27

A fraction in which there is not necessarily any specified relationship between the numerator and denominator.

Question 28

Reference Population

Answer 28

Group from which cases of a disease (or health-related phenomenon under study) have been taken; also refers to the group to which the results of a study may be generalized.

Question 29

Specific rate

Answer 29

Statistic that refers to a particular subgroup of the population defined in terms of race, age, or sex; also may refer to the entire population but is specific for some single cause of death or illness, as in a cause-specific rate.

Question 30

Standardized mortality ratio (SMR)

Answer 30

Number of observed deaths divided by the number of expected deaths during a time period. The analogous term for morbidity is the standardized morbidity ratio.