Deck 3: Measures of Morbidity and Mortality Used in Epidemiology

Question 1

The crude death rate is defined as the number of deaths in a given year divided by a reference population (during the midpoint of the year) times 100,000.

Answer 1

True

Question 2

The point prevalence of a disease is defined as the number of persons ill divided by the total number in the group at a point in time.

Answer 2

True

Question 3

The incidence rate of a disease is defined as the number of new cases of the disease over a time period divided by the total population (at risk) during the same time period times a multiplier (e.g. 100,000).

Answer 3

True

Question 4

When the duration of a disease becomes short and the incidence is high, the prevalence becomes similar to incidence.

Question 5

For a chronic disease of low incidence and long duration, prevalence of the disease increases relative to incidence.

Question 6

Certain diseases can occur more than once in the same individual during a stated period of time. Repeated cases of the disease have no effect upon incidence rates.

Question 7

At the initial examination in the Framingham study, coronary heart disease was found in 5 per 1000 men ages 30-44, and in 5 per 1000 women ages 30-44. The inference that in this age group men and women have an equal risk of getting coronary heart disease is incorrect because the data are prevalence data and not incidence data.

Question 8

The proportional mortality ratio (%) is defined as the mortality due to a specific cause during a time period divided by the mortality due to all causes during the same time period times 100.

Question 9

A prerequisite for using the direct method of age adjustment is that the age-specific death rates in the study population must be stable.

Question 10

Calculation of the standardized mortality ratio is an example of the direct method of age adjustment.

Question 11

Beach City has a rising population of 500,000 robust, fertile males and 450,000 robust, fertile females. If there were 4000 live births, 3 fetal deaths, and 40 maternal deaths, what is the crude birth rate?

A) 4000/500,000 × 1000
B) 4000/450,000 × 1000
C) 4000/950,000 × 1000
D) 4003/950,000 × 1000
E) 3997/950,000 × 1000

Question 12

The risk of acquiring a given disease during a time period is best determined by:

A) the mortality rate from that disease in the 0-4 age group.
B) a spot map that records all cases of the disease in the past year.
C) the period prevalence for that disease during the past year.
D) the incidence rate (cumulative incidence) for that disease in a given period of time.

Question 13

An epidemiologic survey of roller-skating injuries in Metroville, a city with a population of 100,000 (during the midpoint of the year), produced the following data for a particular year:
Number of skaters in Metroville during any given month: 12,000
Roller-skating injuries in Metroville: 600
Total number of residents injured from roller-skating: 1800
Total number of deaths from roller-skating: 90
Total number of deaths from all causes: 900
The crude death rate for all causes was:

A) 90/600 × 100,000.
B) 900/100,000 × 100,000.
C) 90/1,800 × 100,000.
D) 90/900 × 100,000.

Question 14

An epidemiologic survey of roller-skating injuries in Metroville, a city with a population of 100,000 (during the midpoint of the year), produced the following data for a particular year:
Number of skaters in Metroville during any given month: 12,000
Roller-skating injuries in Metroville: 600
Total number of residents injured from roller-skating: 1800
Total number of deaths from roller-skating: 90
Total number of deaths from all causes: 900
The cause-specific mortality rate from roller-skating was:

A) 90/600 × 100,000.
B) 90/100,000 × 100,000.
C) 90/1800 × 100,000.
D) 90/900 × 100,000.

Question 15

An epidemiologic survey of roller-skating injuries in Metroville, a city with a population of 100,000 (during the midpoint of the year), produced the following data for a particular year:
Number of skaters in Metroville during any given month: 12,000
Roller-skating injuries in Metroville: 600
Total number of residents injured from roller-skating: 1800
Total number of deaths from roller-skating: 90
Total number of deaths from all causes: 900
The proportional mortality ratio (%) due to roller-skating was:

A) 90/600 × 100.
B) 90/100,000 × 100.
C) 90/1800 × 100.
D) 90/900 × 100.

Question 16

Which of the following terms is expressed as a ratio (as distinguished from a proportion)?

A) Male Births / Male + Female Births
B) Female Births / Male + Female Births
C) Male Births / Female Births
D) Female Births / Male + Female Births and Male Births / Male + Female Births

Question 17

Which of the following terms is expressed as a proportion (as distinguished from a ratio)?

A) Male Births / Female Births
B) Female Births / Male + Female Births
C) Female Births/ Male Births
D) Female Births / Male + Female Births and Male Births / Female Births

Question 18

Determining workload and planning the scope of facilities and manpower needs, particularly for chronic disease:

A) uses primarily incidence data.
B) uses primarily prevalence data.
C) could use both incidence and prevalence data equally.
D) uses neither incidence data nor prevalence data.

Question 19

Estimating the frequency of exposure:

A) uses primarily incidence data.
B) uses primarily prevalence data.
C) could use both incidence and prevalence data equally.
D) uses neither incidence data nor prevalence data.

Question 20

The fundamental tool for etiologic studies of both acute and chronic diseases:

A) is primarily incidence data.
B) is primarily prevalence data.
C) could equally be both incidence and prevalence data.
D) is neither incidence data nor prevalence data.

Question 21

Expressing the burden or extent of some condition or attribute in a population:

A) uses primarily incidence data.
B) uses primarily prevalence data.
C) could use both incidence and prevalence data equally.
D) uses neither incidence data nor prevalence data.

Question 22

Providing a direct estimate of the risk of developing a disease:

A) uses primarily incidence data.
B) uses primarily prevalence data.
C) could use both incidence and prevalence data equally.
D) uses neither incidence data nor prevalence data.

Question 23

Successful treatment programs that would shorten the duration of a disease primarily affect:

A) the prevalence of the disease.
B) the incidence of the disease.
C) both the incidence and the prevalence of the disease.
D) neither the incidence nor the prevalence of the disease.

Question 24

The major disadvantage of crude rates is that:

A) they may not allow for comparison of populations that differ in size.
B) they do not permit comparison of populations that vary in composition.
C) they are difficult to calculate from available data sources.
D) All are correct.

Question 25

Blood pressure measurements on adult males 30-39 years of age were obtained in a survey of a representative sample of Twin Cities households. To compare the frequency of hypertension in the white and nonwhite populations surveyed, the most appropriate measure is the:

A) incidence rate.
B) prevalence.
C) race-specific incidence rate.
D) race-specific prevalence.
E) race-specific age-adjusted prevalence.

Question 26

The incidence of a disease is five times greater in men than in women, but the prevalence shows no sex difference. The most likely explanation is that:

A) the mortality rate is greater in women.
B) the case fatality rate is greater in women.
C) the duration of the disease is greater in women.
D) women receive less adequate medical care for the disease.

Question 27

Different measures of disease are useful to evaluate and assess public health programs and needs in different situations. For each of the following scenarios, (a) state which measure would best support your goal, and (b) explain why you chose that measure.
Measures of disease:
I = incidence rate
P = prevalence
L = lifetime prevalence
M = crude mortality rate (crude death rate)
R = simple sex ratio
A. To demonstrate the risks of car-train crashes at railroad crossings without warning signals
B. To demonstrate the amount of children's exposure to secondhand cigarette smoke
C. To estimate the number of persons who have had leukemia during their lifetimes
D. To estimate the number of healthcare facilities needed to support patients with Alzheimer's disease
E. To argue that mortality from HIV infection is a more serious public health problem in one region of the United States than another
F. To argue that heart disease should get more funding than HIV
G. To compare the number of boys and girls who experience near-death from drowning in a city

Question 28

Researchers have been trying to gauge the impact of the "graying of America." They report that currently, 5% of the U.S. population is over age 75, and it is expected that in 10 years, 15% of the U.S. population will be over age 75.
A. Do you expect that this shift in age composition will result in shifts in mortality rates? Why or why not?
B. How will you evaluate time trends in mortality rates? Be specific and provide examples.

Question 29

How many people would be needed to accumulate 900 person-years of observation in each row?
Number of people Average time at risk per person
__________ 1 year
__________ 2 years
__________ 3 years
__________ 10 years