Chapter 7 Study Questions PDF

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Chapter 7 Study Questions for Population-based Epi...

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E. Cannon IHP-515 Study Questions

Elizabeth Cannon IHP-515 Chapter 7 Study Questions and Exercises 1, 2, 3, 5, and 6

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E. Cannon IHP-515 Study Questions

Q1/A1). Define in your own words the following terms:  a. Cohort: a group of people who are grouped together. In terms of Chapter 7, a cohort is defined as a group of people who share a common trait, illness, medical condition, historical experience, or social experience.  b. Cohort effect: This occurs when the common trait of the cohort impacts the results of the research.  c. Population-based cohort: a group of people in the general population who share common traits such as gender, sex, age, etc.  d. Exposure-based cohort: in this type of cohort, the people are exposed to the same risk factor as compared to a group of people who were not exposed to the same risk factor.  e. Comparison groups in cohort studies: This refers to the group that is compared to the exposure- based group. Ideally, the comparison group is as similar to the exposure-based group as possible (minus the specific risk factor).  f. Prospective cohort study: a type of cohort study that follows a group of people over a long period of time.  g. Retrospective cohort study- this type of study looks are historical data to investigate the differences in an exposed vs nonexposed group.  h. Ambispective cohort study: this type of study uses historical data or event that have already occurred that allows for future monitoring

Q2). What are secular trends and cohort effects? Explain the relationship between these two terms.

A2). A secular trend is the occurrence of a disease over a prolonged period of time that usually lasts years. Secular trends are influenced by a variety of things such as the degree of immunity in a specific population and also other nonspecific measures that may include factors such as improved air quality of a community or increased/decreased socioeconomic status among a certain population. An example of a secular trend is the decrease in tetanus since the 1920s. A cohort effect, which appears similar to secular trends, occurs when there are different distributions of disease in a population. The varied distribution is caused by an environment that is changing or by a completely new factor that affects age groups differently. A popular example of a cohort effect is the use of computers to measure cognitive tasks. Results show that participants in their 20s perform better than participants in their 60s. These results indicate that people in their 20s are more proficient at using a computer/technology than people in their 60s.

Q3). Explain what is meant by the term relative risk and explain how it is used in cohort studies 2

E. Cannon IHP-515 Study Questions

A3). Relative risk is the ratio of risk of disease/death among the exposed group as compared to the risk of disease/death in the group that was not exposed. This is \ used to measure the association between exposure to a certain factor and disease. Relative risk divides the incidence rate of subjects (numerator) by control subjects (denominator).

Q5.) A cohort study was conducted to study the association of coffee drinking and anxiety in a population-based sample of adults. Among 10,000 coffee drinkers, 500 developed anxiety. Among the 20,000 noncoffee drinkers, 200 cases of anxiety were observed. What is the relative risk of anxiety associated with coffee use?

A5). RR= (500/10,000)/(200/20,000)= 5

Could have been a change in the coding system at a time of death certification in that year. b. The data that is accessed through the ICD can have more than one version, which 3

E. Cannon IHP-515 Study Questions

can cause different results. c. There could be a lack of uniform coding systems that physicians were using. Could have been a change in the coding system at a time of death certification in that year. b. The data that is accessed through the ICD can have more than one version, which 4

E. Cannon IHP-515 Study Questions

can cause different results. c. There could be a lack of uniform coding systems that physicians were using. Q6.) How is a case-control study different from a retrospective cohort study? List the key criteria that, in general, would influence you to select one approach over the other.

A6). Case-control study: This type of study compares people with a disease/health outcome to people without a disease/health outcome. The study looks back retrospectively to compare how frequently each group was exposed to the risk factor in order to determine the relationship between said risk factor and the disease. These types of studies are purely observational as there is no intervention to change the outcome or course of the disease. The only goal of this type of study is to determine the exposure to the risk factor and are designed to estimate odds. Case control studies are a good option when studying rare conditions. Other advantages: less time spent on the study, allows the observer to look at multiple risk factors simultaneously and useful when looking to establish an association. Retrospective cohort study: This type of study is also known as historical cohort studies. It is conducted in present time but looks at historical data to examine medical events or outcomes. Unfortunately, in this study design the investigator has limited control over the collection data and the data has the potential to be incomplete, inaccurate, or measured inconsistently. Because data is immediately available, a retrospective cohort study is less costly and can be conducted in a shorter amount of time (compared to other studies). The intent of a case-control study is to determine exposure risk factors after a known incidence of a disease. The intent of a retrospective cohort study is to compare the risk of developing a disease to already known exposures in the environment.

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E. Cannon IHP-515 Study Questions

References Friis, R. H. & Sellers, T. A. (2014). Epidemiology for Public Health Practice. Burlington: Jones and Bartlett Learning.

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