Deck 7: Study Designs: Cohort Studies

Question 1

Cohort studies preserve the temporality of cause (exposure) happening before the effect (disease).

Answer 1

True

Question 2

Repeated cross-sectional surveys may underestimate past smoking behavior of older segments of the current population.

Answer 2

True

Question 3

Survival curves may be used to portray patients' survival in clinical studies.

Answer 3

True

Question 4

Exposure-based cohort studies permit investigations of exposures that are uncommon.

Question 5

Relative risk is the ratio of the risk of disease among the exposed to the risk among the unexposed.

Question 6

Failing to account for age cohort effects in smoking prevalence may:

A) obscure the fact that older cohorts had higher prevalence of smoking in comparison to younger cohorts.
B) obscure the fact that there had been a shift in the age of onset for lung cancer toward earlier ages.
C) obscure the differences in smoking prevalence for males and females, and by level of education.
D) obscure the fact that there had been a shift in the age of onset for lung cancer toward earlier ages as well as the differences in smoking prevalence for males and females, and by level of education.

Question 7

As an epidemiologist, you are going to investigate the effect of a drug suspected of causing malformations in newborn infants when the drug in question is taken by pregnant women during the course of their pregnancies. As your sample you will use the next 200 single births occurring in a given hospital. For each birth, a medication history will be taken from the new mother and from her doctor; in addition, you will review medical records to verify use of the drug. (Note: These mothers are considered to have been followed prospectively during the entire course of their pregnancies, because a complete and accurate record of drug use was maintained during pregnancy.) The resultant data are: Forty mothers took the suspected drug during their pregnancies. Of these mothers, 35 delivered malformed infants. In addition, 10 other infants were born with malfunctions.
The relative risk between exposure to the drug and malformations is:

A) 10.
B) 12.
C) 14.
D) 16.
E) 18.

Question 8

As an epidemiologist, you are going to investigate the effect of a drug suspected of causing malformations in newborn infants when the drug in question is taken by pregnant women during the course of their pregnancies. As your sample you will use the next 200 single births occurring in a given hospital. For each birth, a medication history will be taken from the new mother and from her doctor; in addition, you will review medical records to verify use of the drug. (Note: These mothers are considered to have been followed prospectively during the entire course of their pregnancies, because a complete and accurate record of drug use was maintained during pregnancy.) The resultant data are: Forty mothers took the suspected drug during their pregnancies. Of these mothers, 35 delivered malformed infants. In addition, 10 other infants were born with malfunctions.
Suppose that a relative risk of 0.5 has been found. Which interpretation might follow?

A) The risk of congenital malformations is half as high among users of the drug as among nonusers.
B) The risk of congenital malformations is equal among users and nonusers of the drug.
C) The risk of congenital malformations is twice as high among users of the drug as among nonusers of the drug.
D) Use of the drug is a protective factor for congenital malformations.
E) The risk of congenital malformations is half as high among users of the drug as among nonusers, and use of the drug is a protective factor for congenital malformations.

Question 9

As an epidemiologist, you are going to investigate the effect of a drug suspected of causing malformations in newborn infants when the drug in question is taken by pregnant women during the course of their pregnancies. As your sample you will use the next 200 single births occurring in a given hospital. For each birth, a medication history will be taken from the new mother and from her doctor; in addition, you will review medical records to verify use of the drug. (Note: These mothers are considered to have been followed prospectively during the entire course of their pregnancies, because a complete and accurate record of drug use was maintained during pregnancy.) The resultant data are: Forty mothers took the suspected drug during their pregnancies. Of these mothers, 35 delivered malformed infants. In addition, 10 other infants were born with malfunctions.
What type of study design is this?

A) Retrospective cohort study
B) Prospective cohort study
C) Historical prospective study
D) Ambispective cohort study
E) None of these is correct.

Question 10

As an epidemiologist, you are going to investigate the effect of a drug suspected of causing malformations in newborn infants when the drug in question is taken by pregnant women during the course of their pregnancies. As your sample you will use the next 200 single births occurring in a given hospital. For each birth, a medication history will be taken from the new mother and from her doctor; in addition, you will review medical records to verify use of the drug. (Note: These mothers are considered to have been followed prospectively during the entire course of their pregnancies, because a complete and accurate record of drug use was maintained during pregnancy.) The resultant data are: Forty mothers took the suspected drug during their pregnancies. Of these mothers, 35 delivered malformed infants. In addition, 10 other infants were born with malfunctions.
The number of individuals who both did not take the drug and did not give birth to infants who were malformed was:

A) 140.
B) 150.
C) 155.
D) 160.
E) 170.

Question 11

A major advantage of cohort studies over case-control studies with respect to the role of a suspected factor in the etiology of a disease is that:

A) they take less time and are less costly.
B) they can utilize a more representative population.
C) it is easier to obtain controls not exposed to the suspected factor.
D) they permit direct determination of risk of disease in those exposed to the suspected factor.
E) they can be done on a double-blind basis.

Question 12

A five-year prospective cohort study has just been completed. The study was designed to assess the association between supplemental vitamin A exposure and mortality and morbidity for measles. The RR for incidence of measles was 0.75, and the RR for measles mortality was 0.5. Which statement is correct?

A) A cohort study is not an appropriate study design in this case because the association between one exposure and two different outcomes is being considered.
B) One of the problems that this study may have faced is individuals lost to follow-up during the five-year period.
C) A cohort study is not a good design to study this association because measles is a very common disease.
D) Supplemental vitamin A increases the incidence of measles.
E) None of these is correct.

Question 13

A five-year prospective cohort study to assess the association between supplemental vitamin A exposure and mortality and morbidity for measles has just been completed. The RR for incidence of measles was 0.75, and the RR for measles mortality was 0.5. Regarding the RR, which statement is correct?

A) Exposure to vitamin A appears to protect against morbidity and mortality for measles.
B) Exposure to vitamin A appears to be a risk factor for morbidity and mortality for measles.
C) Exposure to vitamin A is not associated with morbidity and mortality for measles.
D) Exposure to vitamin A is a risk factor for morbidity and a protective factor for mortality for measles.

Question 14

Cohort study is to risk ratio as:

A) ecologic fallacy is to cross-sectional study.
B) genetics is to environment.
C) case-control study is to odds ratio.
D) ecologic fallacy is to cross-sectional study and case-control study is to odds ratio.

Question 15

Which of the following individuals helped draw people's attention to the method of cohort analysis?

A) Snow
B) Frost
C) Graunt
D) Hill

Question 16

Which of the following studies is an example of a population-based cohort study?

A) Tecumseh Study
B) Framingham Study
C) Iowa Women's Health Study
D) All are correct.

Question 17

Subjects for an exposure-based cohort study of lead exposure would be selected most appropriately from:

A) certain occupational groups such as workers who manufacture batteries.
B) the residents of a large U.S. county.
C) male Harvard alumni from 1916 to 1950.
D) All are correct.

Question 18

An ambispective cohort study is also known as a:

A) nested case-control study.
B) prospective cohort study.
C) historical prospective study.
D) retrospective cohort study.

Question 19

Practical considerations in the design of cohort studies do not usually include:

A) availability of exposure data.
B) size and cost of the cohort.
C) follow-up issues.
D) scientific justification.
E) age of the investigator.

Question 20

Nested case-control studies:

A) use subjects drawn from a cohort study.
B) provide a degree of control over confounding.
C) reduce the cost of collecting exposure information.
D) All are correct.

Question 21

An example of passive follow-up in cohort studies is:

A) collection and maintenance of data by federal and state governments.
B) telephone calls to study participants.
C) use of follow-up mailings.
D) use of written invitations to return to the study site.

Question 22

A case-cohort study differs from a nested case-control study by:

A) not using controls.
B) not using matching.
C) inability to study occupational exposures.
D) None of these is correct.