Exercise 4 Chapters 8, 9 & 12(1)
docx
keyboard_arrow_up
School
Southern Illinois University, Edwardsville *
*We aren’t endorsed by this school
Course
PBHE-530
Subject
Health Science
Date
Apr 3, 2024
Type
docx
Pages
7
Uploaded by DrTitanium13960
Exercise 4 Chapters 8, 9, & 12 (30 questions, 1 point per 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
2. 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.
3. 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.
4. 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
5. 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
6. 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.
1
7. 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
8. Epidemiologists decided to investigate the effect of sunscreens on sunburns. They ran an epidemiologic study to see the association of sunscreens and sunburns. Overall, 460 people have enrolled in the study. Investigators randomly allocated 230 people to the treatment group (sunscreens) and 230 to the control group (placebo). They exposed those 460 people to the high mountain trail on a sunny day. At the end of the study, 30 people developed sunburns in the sunscreen group and 130 people developed sunburns in the placebo group. What is the risk of developing sunburns in the placebo group?
a. 0.13
b. 0.15
c. 0.23
d. 0.57 (130/230)
e. 1
9. Epidemiologists decided to investigate the effect of sunscreens on sunburns. They ran an epidemiologic study to see the association of sunscreens and sunburns. Overall, 460 people have enrolled in the study. Investigators randomly allocated 230 people to the treatment group (sunscreens) and 230 to the control group (placebo). They exposed those 460 people to the high mountain trail on a sunny day. At the end of the study, 30 people developed sunburns in the sunscreen group and 130 people developed sunburns in the placebo group. What is the relative risk of sunburns in the sunscreen treatment group compared with the control group in this study?
a. 0.12
b. 0.13
c. 0.23
d. 1.33
e. 4.33
10. Which of the following measures represents the absolute risk of getting a disease?
a. Prevalence
b. Odds ratio
c. Risk ratio
d. Incidence
e. Risk difference
11. The following table summarizes the findings of a cohort study. Participants were enrolled in January 1,
2015, and followed up until December 31, 2015. Researchers were interested in the effect of physical activity on cardiovascular disease.
Cardiovascular events
No events
Total
Physically active
28
1,972
2,000
Inactive
75
2,925
3,000
Based on the previous information, calculate the incidence per 1,000 per year of cardiovascular events among those who were categorized as physically active.
a. 14/1,000 per year = 28/2000 b. 25/1,000 per year
2
c. 28/1,000 per year
d. 75/1,000 per year
e. 99/1,000 per year
12. The following table summarizes the findings of a cohort study. Participants were enrolled in January 1,
2015, and followed up until December 31, 2015. Researchers were interested in the effect of physical activity on cardiovascular disease.
Cardiovascular events
No events
Total
Physically active
28
1,972
2,000
Inactive
75
2,925
3,000
Based on the previous information, calculate the relative risk of cardiovascular events for those who were physically active. a. 0.38
b. 0.56 = (28/2000)/(75/3000) = 0.014/0.025 = 0.56
c. 1.50
d. 1.79
e. 2.68
13. Consider the following 2
2 table from a hypothetical cohort study. Calculate the incidence of cardiovascular disease (CVD) among the not exposed participants.
Serum fasting glucose
Developed CVD
Did not develop CVD
Total
126 mg/dL (exposed)
125
325
450
<126 mg/dL (not exposed)
50
500
550
Total
175
825
1000
a. 9 per 100 population 50/550 = 0.09
b. 28 per 100 population
c. 44 per 100 population
d. 50 per 175 population
e. 72 per 100 population
14. Consider the following 2
2 table from a hypothetical cohort study. Calculate the relative risk of CVD comparing those with high fasting glucose (
126 mg/dL) with those with normal fasting glucose (<126 mg/dL)
Serum fasting glucose
Developed CVD
Did not develop CVD
Total
126 mg/dL (exposed)
125
325
450
<126 mg/dL (not exposed)
50
500
550
Total
175
825
1000
a. 0.33
b. 0.75
c. 1.02
d. 3.08 (125/450)/ (50/550) = 0.2779/0.09 = 3.08
e. 5.34
15. A study is planned to investigate the relationship of factors associated with maternal hypertension and
the risk of congenital birth defects in children born to these women. Which of the following would be a reason for using a cohort study design?
a. The need to obtain data on the incidence of early fetal losses due to congenital birth defects
b. The low rate of congenital birth defects
c. The development of pregnancy-related hypertension in asymptomatic women
d. The consistency of recall of risk factors among women having children with and without congenital birth
defects and those having children
3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
e. Testing hypotheses about several different risk factors for congenital birth defects such as maternal age, diabetes, and previous miscarriage history
16. A researcher is interested in the etiology of myocardial infarction (MI) among men between 18 and 40 years of age. Her hypothesis concerns the influence of diets high in fat and subsequent development of MI. What is the best study approach to address this hypothesis?
a. Case-control study with cases of MI identified post-event and controls sampled from healthy men in the
population, then have both groups complete dietary surveys
b. Case-report study describing the dietary habits in 100 men having an MI
c. Ecologic study with the rates of MI compared between cities with higher than average dietary fat intakes and cities with lower than average dietary fat intakes
d. Retrospective cohort study with medical records used to collect information on diet among men with and without an MI
e. Prospective cohort study identifying a population of men in this age group, administering a dietary survey and classifying men by high and low-fat diet, then following both groups for the development of an MI
17. Which of the following is an advantage to the conduct of a cohort study?
a. The study population is the same with regard to the risk factors for disease
b. The disease under study occurs rarely in the population
c. The incidence of the disease is high in the nonexposed group
d. The incidence of the disease is high in the exposed group
e. The study population includes a high number of undiagnosed, asymptomatic individuals with the disease
18. A cohort study is planned to investigate the potential adverse health effects of daily alcohol consumption. In assessing the risk of liver cancer related to alcoholism, which of the following is not an important methodologic consideration?
a. The need to study a large number of persons for a rare disease outcome
b
. The difficulty of finding enough persons with liver cancer at the beginning of the study in whom alcohol consumption could be determined.
c. The possible bias associated with persons describing alcohol usage
d. The likelihood that doctors would monitor alcoholics more closely for liver cancers
e. The possibility that persons would change their alcohol consumption practices during the study period
19. Which of the following is not an advantage of a retrospective cohort study?
a. Allows for the study of many disease outcomes resulting from an exposure
b. Incidence rates can be calculated
c
. Possible bias due to selection of the cohort is eliminated
d. Potential recall bias can be minimized
e. Requires less follow-up time than a prospective cohort study
20. In a study of the adverse effects of x-rays among children, a retrospective cohort study was done using records from several large children's hospitals for the period of 1980 to 1985. 10,000 children were selected as a representative population of ill children seen at the hospitals during that time. Subjects were
classified according to whether or not they received an x-ray during their stay in the hospital and were followed from their hospital stay through 2005 for the development of cancer. During the follow-up period, 49 incident cancers occurred in 3,263 children who had received an x-ray, and 47 incident cancers occurred in the 6,737 children who had not received an x-ray during their hospitalization. What are the rates of cancer incidence in exposure and non-exposure groups?
Exposure: 15 per 1000 (49/3263)
Non-Exposure: 7 per 1000 (47/6737) = 6.9 approx 7 21. In a study of the adverse effects of x-rays among children, a retrospective cohort study was done using records from several large children's hospitals for the period of 1980 to 1985. 10,000 children were selected as a representative population of ill children seen at the hospitals during that time. Subjects were
4
classified according to whether or not they received an x-ray during their stay in the hospital and were followed from their hospital stay through 2005 for the development of cancer. During the follow-up period, 49 incident cancers occurred in 3,263 children who had received an x-ray, and 47 incident cancers occurred in the 6,737 children who had not received an x-ray during their hospitalization. Which of the following issues should the investigators consider when interpreting whether a causal association exists between cancer incidence and childhood x-ray?
a. Some study subjects were treated for cancer starting in 1980
b. Some study subjects had parents who were diagnosed with cancer
c. Some children received x-rays at other hospitals not included in this study
d. The children were different ages when they were admitted to the hospital
e
. All of the above
22. 6,750 people who were free of disease X were enrolled in a cohort study in 1985 and followed with annual exams and interviews through 1995. Exposure to factor A was determined at study enrollment and
the participants were followed until 1995 to observe new cases of disease X. Data from the study at the end of follow-up are shown in the following table. What is the incidence rate of disease X among persons exposed to factor A?
a. 0.04 (120 / 120+2880) = 120/3000 = 0.04
b. 0.19
c. 0.25
d. 4.00
e. 5.17
23. 6,750 people who were free of disease X were enrolled in a cohort study in 1985 and followed with annual exams and interviews through 1995. Exposure to factor A was determined at study enrollment and
the participants were followed until 1995 to observe new cases of disease X. Data from the study at the end of follow-up are shown in the following table. What is the relative risk for the effect of exposure to factor A on disease X?
a. 0.20
b. 1.29
c. 4.00
d. 5.00 (120/3000) / 30/3750) = 0.04/0.008 = 5
e. 5.17
24. In 2002, investigators started a study of the association of cholesterol levels and stroke in a group of 2,000 healthy persons who had participated in a cholesterol screening program in 1992. The investigators determined exposure categories using cholesterol levels in all persons that were measured at the time of the screening program. A cutoff value of 200 mg/dL was used to define "high" cholesterol while those with levels below 200 were identified as having "low" cholesterol. Using this definition, 1,000 persons had "high" cholesterol levels while the remaining 1,000 persons had "low" cholesterol. The investigators determined that 150 cases of stroke occurred by the end of 2004, with 113 cases occurring in the high cholesterol group. What is the study design that the investigators 5
used?
a. Case-control study
b. Retrospective cohort study
c. Prospective cohort study
d. Cross-sectional study
e. Randomized clinical trial
25. In 2002, investigators started a study of the association of cholesterol levels and stroke in a group of 2,000 healthy persons who had participated in a cholesterol screening program in 1992. The investigators determined exposure categories using cholesterol levels in all persons that were measured at the time of the screening program. A cutoff value of 200 mg/dL was used to define "high" cholesterol while those with levels below 200 were identified as having "low" cholesterol. Using this definition, 1,000 persons had "high" cholesterol levels while the remaining 1,000 persons had "low" cholesterol. The investigators determined that 150 cases of stroke occurred by the end of 2004, with 113 cases occurring in the high cholesterol group. What type of risk measure should the investigators calculate?
a. Odds ratio
b. Prevalence rate
c. Multiplicative interaction
d. Positive predictive value
e. Relative risk
26. In 2002, investigators started a study of the association of cholesterol levels and stroke in a group of 2,000 healthy persons who had participated in a cholesterol screening program in 1992. The investigators determined exposure categories using cholesterol levels in all persons that were measured at the time of the screening program. A cutoff value of 200 mg/dL was used to define "high" cholesterol while those with levels below 200 were identified as having "low" cholesterol. Using this definition, 1,000 persons had "high" cholesterol levels while the remaining 1,000 persons had "low" cholesterol. The investigators determined that 150 cases of stroke occurred by the end of 2004, with 113 cases occurring in the high cholesterol group. Using the reported study data, what is the estimate of the risk measure that was chosen?
a
. 3.1 (113/1000) / (37/1000) = 0.113/0.037 = 3.05 = 3.1
b. 3.3
c. 67%
d. 1.0
e. 0.3
27. In 2002, investigators started a study of the association of cholesterol levels and stroke in a group of 2,000 healthy persons who had participated in a cholesterol screening program in 1992. The investigators determined exposure categories using cholesterol levels in all persons that were measured at the time of the screening program. A cutoff value of 200 mg/dL was used to define "high" cholesterol while those with levels below 200 were identified as having "low" cholesterol. Using this definition, 1,000 persons had "high" cholesterol levels while the remaining 1,000 persons had "low" cholesterol. The investigators determined that 150 cases of stroke occurred by the end of 2004, with 113 cases occurring in the high cholesterol group. What is a necessary assumption for the study's findings to be true?
a. There is no recall bias among the study participants
b. The cholesterol level measured in 1992 is a valid determinant of exposure status during the entire study period
c. The high and low cholesterol groups are randomly assigned
d. The age distribution of the cases and controls is equivalent
e. The cholesterol measure is modified by cigarette smoking practice
28. The following data are from a prospective study that examined the relationship between smoking and incidence of both myocardial infarction (heart attack) and breast cancer among women. What is 6
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
the relative risk of myocardial infarction for smokers?
a. 0.86
b. 1.0
c. 1.3 (incidence is given therefore: 100/80 = 1.25 = 1.3
d. 2.0
e. Cannot be calculated because the nondiseased numbers are not given
29. When is odds ratio obtained in a case-control study a reliable approximation of the relative risk for the general population?
a. The exposure distribution among cases is representative of all persons with disease
b. The exposure opportunity for controls is equivalent to the distribution of exposure opportunities for the population without the disease
c. When the disease under investigation is rare in the population
d. a and b only
e. All of the above
30. Investigators wanted to know if some military personnel are more error prone than others and would be a poor risk for training as a pilot. A study was done in which individuals who had injuries during basic training were compared to individuals who had not had an injury during training. Both groups were asked to recall episodes during childhood when they had had accidents that resulted in an injury. The individuals
with a training injury reported more incidents during childhood when they had an injury. Therefore, the military command concluded that some persons are more likely to be error prone and that individuals with
a childhood injury should be excluded from pilot training.
One commanding officer disagreed with this conclusion. He asked the investigators to design a second study in which all individuals were asked about childhood injuries prior to the start of basic training. The group who reported having a childhood injury was compared to the group who had not had a childhood injury to determine which group had a higher rate of injuries during basic training. At the end of follow-up, there was no difference in the rate of injuries experienced by each group.
What type of study design was used for the second study?
a. Cross-sectional
b. Case-control
c. Retrospective cohort
d. Prospective cohort
e. Randomized clinical trial
7