Deck 8: Cohort Studies

Question 1

Some researchers want to investigate the association of work stress and risk of cardiovascular mortality.Investigators selected a systematic sample of 902 participants in strata by sex,age,and occupational group from the Valmet factories in Jyväskylä,in central Finland.Baseline examination in 1973 determined cases of cardiovascular disease,behavioral and biologic risks,and stressful characteristics of work.Follow-up examinations included measurement of blood pressure,cholesterol concentration,and body mass index in 1978 and in 1983.[Kivimäki M,Leino-Arjas P,Luukkonen R,et al.Work stress and risk of cardiovascular mortality: a study of industrial employees.BMJ 2002;325(7369):857.] What kind of study design is this?

A) Cross-sectional study
B) Prospective cohort study
C) Case-control study
D) Randomized trial
E) Case report

Answer 1

B
Investigators defined their exposure (work stress),followed up the participants,and measured outcome (cardiovascular mortality)."Cross-sectional study" is not correct; they did not capture all information (exposure and outcome) from participants at the same time."Case-control study" is not correct; they did not classified participants by disease status."Randomized trial" is not correct; they did not randomly allocate exposure status."Case report" is not correct; they did not report a single or series of disease cases.

Question 2

In which of the following study designs is possible to calculate incidence rate?

A) Cross-sectional
B) Case-control
C) Cohort
D) Case-series
E) Report of a case

Answer 2

C
To calculate incidence,it is necessary to follow up a group of individuals without the disease to detect new cases.The only option that describes such a study is a cohort study.

Question 3

The Baltimore Longitudinal Study of Aging (BLSA) is a research study of normative aging started in the 1950s.Volunteers,free of chronic conditions,are recruited and followed every 4,2,or 1 year(s) until their death.What type of study design is this?

A) Cross-sectional
B) Ecologic
C) Randomized trial
D) Retrospective cohort
E) Prospective cohort

Answer 3

E
This is a prospective observational longitudinal study.These characteristics are unique of a prospective cohort study.

Question 4

The main difference between a cohort study and a randomized trial is that

A) cohort studies are longitudinal and randomized trials are cross-sectional.
B) only clinical trials can evaluate the effect of a drug.
C) randomized trials are experimental and cohort studies are observational.
D) clinical trials are observational and cohort studies are experimental.
E) at the beginning of a clinical trial, participants are free of disease, and cohort studies start with patients with a disease.

Question 5

Which of the following statements is the most accurate characteristic of the nested case-control study?

A) A control who is selected early in the study could later develop the disease but cannot be a case in the same study.
B) In nested case-control studies, controls are a sample of individuals who are at risk for the disease at the time each case of disease develops.
C) Controls are randomly chosen from the defined cohort with which the study began.
D) The problems of possible recall bias from conventional case-control studies still remains.
E) Nested case-control studies are often less economical to conduct.

Question 6

In 1999 the army of country Z started to collect data from all their recruits.As part of the process,they conducted a full physical examination in which audition was measured and reported as normal hearing,low hearing loss,and severe hearing loss.Unfortunately,5 years later country Z went into a war with country Y.In 2018 a researcher from University U decided to conduct a study in which she investigated the association between hearing loss and suffering a war injury.What type of study design is being illustrated in this example?

A) Case-control study
B) Cross-sectional study
C) Ecologic study
D) Prospective cohort study
E) Retrospective cohort study

Question 7

Which of the following statements is the most accurate characteristic of cohort studies?

A) It is an efficient study designs for studying rare disease.
B) The temporality of the exposure preceding the outcome is hard to determine.
C) The incidence rate of disease in the exposure group is compared directly to the incidence rate of disease in the unexposed group.
D) The exposure and outcomes are captured at the same time.
E) The participants are randomly allocated to exposure and nonexposure categories.