Questions 1 and 2 are based on the following information:
You are called to investigate a possible health problem in an office building that may be due to a potential environmental toxin. You arrange with a company that occupies two levels of the building to follow all 300 office employees for 30 days. Every day the employees report their health status. Nothing happens until day 10, when 35 employees report of respiratory distress. On day 20, 70 employees report of respiratory distress. The remaining employees do not report any problems over the 30 day period.
What is the incidence rate of respiratory distress in this study population?
a. 1.4 per 100 person-days
b. 2.1 per 100 person-days
c. 2.8 per 100 person-days
d. 1.0 per 100 person-days
What is the cumulative incidence of respiratory distress over a 30-day period?
c. 11.6 per 100 person-days
d. 35 per 100 person-days
Question 3 is based on the following data among women in the United States (US)
3.Based on the information provided, what can you conclude about the crude mortality rate from cervical cancer among women 30-49 years of age in the US?
a. The crude mortality rate from cervical cancer among women 30-49 years of age was 1.2 times higher in 1980 than in 2000.
b. The crude mortality rate from cervical cancer among women 30-49 years of age was the same in 1980 as it was in 2000.
c. The crude mortality rate from cervical cancer among women 30-49 years of age was 1.2 times higher in 2000 than in 1980.
d. The crude mortality rate from cervical cancer among women 30-49 years of age cannot be calculated either for 1980 or 2000.
Questions 4 and 5 are based on the following information:
Imagine researchers have developed a new rapid screening test for tuberculosis, which they hope will replace the sputum culture (reference standard). To pilot this new test, 1,000 participants were given both test.
4. What is the specificity of the new rapid test for detecting tuberculosis (tuberculosis is defined as positive for sputum culture test)? Show your work, and report your answer as a percent rounded to the percent’s tenths decimal place (i.e., to the nearest 0.1%). (If no work is shown, half credit will be deducted from the grading of your response to this question, even if your final answer is correct.)
Your answer will appear here.
If the true prevalence of tuberculosis were to decrease in the above study population, what effect would this have on the positive predictive value of the new rapid test for detecting tuberculosis?
a. The positive predictive value would increase.
b. The positive predictive value would decrease.
c. The positive predictive value would not change.
d. The impact on the positive predictive value would depend on the sensitivity.
Which of the following options best represents the term “incubation period”?
a. The period of time from infection in one individual (i.e., primary case) to when that individual infects another individual (i.e., secondary case).
b. The time between when a person can first transmit the infection and when he/she can no longer transmit the infection.
c. The time from infection by an infectious disease in an individual to that individual’s first clinical sign or symptom of the disease.
d. The period between when an individual becomes infected and when he/she can begin to transmit the disease to others.
Question 7 is based on the following information:
_________ surveillance: a system by which the public health authority receives reports submitted from hospitals, clinics, or other sources for dozens of notifiable diseases, such as rabies. _________ surveillance is a relatively inexpensive strategy to cover large areas, and it provides critical information. However, even though it may be required by law, this surveillance depends on people in different institutions to provide data, so data quality and timeliness are difficult to control.
Questions 8 and 9 are based on the following information:
An unusually high number of students presented to the University Health Clinic with symptoms of gastrointestinal illness. Many reported having eaten in the dining hall after the football game on Saturday afternoon. Members of the Introduction to Epidemiology class were asked to conduct an investigation.
Six hundred students were identified as having eaten in the dining hall at 5:00 PM on Saturday. Of these, half the students reported symptoms of gastrointestinal illness.
The investigators identified potato salad, turkey burgers, shrimp salad, and cream pie as the foods that were served in the dining hall at 5:00 PM. All six hundred students who ate then in the dining hall were interviewed. The table below contains a summary of the data collected.
8. What is the difference in attack rates (i.e., risk difference) between students who ate the turkey burger and students who did not eat the turkey burger?
Which food is the most likely cause of the epidemic?
a. Potato salad
b. Turkey burger
c. Shrimp salad
d. Cream pie
Questions 10 and 11 are based on additional information:
The student investigators also collected the time of onset of symptoms for each of the students who were sick:
10. What is the median incubation period (in hours) for this outbreak assuming the exposure occurred at 5:00 PM on Saturday (i.e., hour zero)?
a. 6 hours
b. 7 hours
c. 5 hours
d. 4 hours
How would you describe this epidemic?
a. Point source epidemic with direct transmission
b. Point source epidemic with indirect transmission
c. Propagated epidemic with direct transmission
d. Propagated epidemic with indirect transmission
Questions 12 and 13 are based on the following information:
What type of study design is described above?
a. Cross-sectional study
b. Cohort study
c. Case-control study
d. Ecologic study
Based solely on the information provided, the conclusion that higher levels of per capita sugar consumption are associated with higher country-level age-adjusted prostate cancer incidence is:
b. Incorrect because of failure to distinguish between degrees of exposure to the outcome of interest
c. Incorrect because of failure to distinguish between disease incidence and disease prevalence
d. Incorrect because of failure to distinguish between disease incidence and disease mortality
Which option below best represents the main difference between cohort studies and clinical trials?
a. The investigator and other study staff are masked in a cohort study but not in a clinical trial
b. Cohort studies are conducted with humans and clinical trials are conducted with animals
c. Study investigators control the participant’s exposure in clinical trial, but not in a cohort study
d. Study investigators follow up participants over time in clinical trials, but not in cohort studies
Which of the following statements is FALSE about randomization and masking in clinical trials? SELECT ALL THAT APPLY.
a. Randomization is done to conceal treatment assignment.
b. Randomization eliminates bias in the choice of treatment.
c. Masking ensures study groups are comparable at baseline.
d. Masking minimizes bias related to prior knowledge or beliefs about the treatment for the scientists conducting the study.
Choose the best study design from the list below for each of the research questions. Each study design can only be used once.
|Questions 17-19 are based on the following information:
An epidemiologist is interested in novel risk factors associated with incident breast cancer in women, which could be potential therapeutic targets for future interventions. She proposed a prospective cohort study design to study these factors in middle-aged women and requested funding for 15 years of follow-up. She intends to recruit participants from five primary care clinics around the United States in 2020.
Which of the following best describes the target population of this proposed study? Select the ONE best answer.
a. All middle-aged women who have primary care appointments at the five clinic sites where the study is recruiting in 2020.
b. All middle-aged women in the United States in 2020.
c. All middle-aged women in the United States who do not have breast cancer in the 21st century and beyond.
d. All middle-aged women in the United States with breast cancer in the 21st century and beyond.
e. All middle-aged adults in the United States
Which of the following groups of individuals should certainly be excluded during screening for enrollment? Select ALL that apply:
a. Women previously diagnosed with breast cancer, who are currently in remission.
b. Women never diagnosed with breast cancer who report a family history of breast cancer
c. Women never diagnosed with breast cancer who report no family history of breast cancer
d. Women currently receiving chemotherapy for breast cancer
e. Men with a family history of male breast cancer
The funding agency told the epidemiologist that resources were limited and requested she design a more efficient study to answer this research question. What is the best alternative study design that the epidemiologist should consider?
a. Cross-sectional study of cancer-free women identified at high risk of breast cancer
b. An ecologic study of neighborhood level overall cancer prevalence and the prevalence of risk factors from census data
c. A case-control study nested in an existing longitudinal cohort to compare women with breast cancer to women without breast cancer
d. A randomized clinical trial of an experimental intervention that targets the epidemiologist’s hypothesized most important novel risk factor
e. There are no alternative study designs for this research question. The prospective cohort study is the only valid way to answer this research question
|Questions 20 and 21 are based on the information provided below:
Alzheimer’s Disease is most commonly seen in older adults. The United States population has a much higher proportion of older adults compared to the World population.
If the crude incidence rates of Alzheimer’s Disease in the United States were age standardized to the World population, what would you conclude regarding the age standardized and crude rates?
a. The age standardized rate would be the same as the crude rate.
b. The age standardized rate would be less than the crude rate.
c. The age standardized rate would be greater than the crude rate.
d. There is no basis for comparison with age standardized rates.
e. Age standardized rates are best for public health planning purposes.
Which of the following statement(s) is(are) true about the standardization described above? Select ALL that apply.
a. This is an example of direct standardization.
b. The standard population used is the United States population.
c. If we also standardized the rates of Alzheimer’s Disease observed in the French population to the World population, then we could compare the age standardized rates from the United States to the age standardized rates from France.
d. None of the above are true.
A small proportion of people who acquire OPAL fever die from it. The duration of the disease is approximately 2 weeks and for those who survive it, there is life-long immunity. Which of the following would result in a decrease in the incidence of OPAL fever in a given population?
a. Primary prevention
b. Secondary prevention
c. An increase in the case fatality
d. Improving survival from OPAL fever
e. Decreasing the duration of OPAL fever through improved treatment
Match the following terms to their corresponding descriptor. Please note each term may only be used once.
Which statement describes how a prospective cohort study is different from a case-control study?
a. It is an observational study.
b. It is a study design in which a measure of association can be calculated.
c. It is a form of study design where participants are usually separated into two different comparison groups.
d. It is a study design that allows one to assess multiple exposures.
e. It is a study design that allows one to assess multiple outcomes.
Which of the following statements is FALSE?
a. Prevalence is a measure of disease burden.
b. Active surveillance tends to be more expensive than passive surveillance.
c. Endemic disease is defined as the constant presence of a disease within a specified geographic area.
d. For herd immunity to successfully protect individuals, 100% of the population must be immunized.
e. All of the above .
|Dr. Johnson started a longitudinal study on medication use and dementia, which recruited 500 patients aged 65 years and older from 4 clinical sites. Participants provided data on demographics, lifestyle factors, and medication history at two time points: baseline and 5-years after baseline. Dementia status was also assessed at the same two time points via a local adjudication committee using the Diagnostic and Statistical Manual of Mental Disorders, 4th edition.|
Dr. Johnson wants to examine whether prior use of anticholinergic drugs at age 35 (one of the questions asked at baseline) is associated with dementia. She identifies participants with a dementia diagnosis at baseline and selects age- and sex-matched controls, who are dementia-free at baseline. What type of study design is she using with the baseline data? (Check all that apply)
c. Randomized controlled trial
Dr. Johnson finds that those with adjudicated dementia diagnoses at baseline tend to have similar usage of anticholinergics when compared to counterparts without dementia. So then, she wants to assess whether current (baseline) anticholinergic use differed between participants with dementia at baseline compared to those who did not have dementia at baseline. What study design is she implementing? (Check all that apply)
a. Case-control study design
b. Cohort study design
c. Experimental study design
d. Cross-sectional study design
e. Observational study design
After the study ends, Dr. Johnson provides you access to the full dataset. Imagine you are interested in characterizing the degree to which age is associated with future dementia diagnoses using this dataset. What study design do you use and who do you include in your analysis?
a. Randomized controlled trial, all participants
b. Cohort, all participants
c. Case-control, participants without dementia diagnosis at baseline
d. Ecological, participants with dementia diagnosis at baseline
e. Cohort, participants without dementia diagnosis at baseline
Dr. Johnson published a paper investigating the relationship between exposure to anticholinergic medications at baseline and dementia incidence. The authors present a(n) __________ of 1.25. What term best fills in the blank?
a. Attributable risk
b. Relative risk (or risk ratio)
c. Risk difference
d. Attack rate
Which of the following is/are classified as an observational study (studies)? (select all that apply):
a. Cohort study
b. Case-control study
c. Randomized controlled trial
d. Cross-sectional study
A research team was interested in maternal geographic movements in an area with endemic Zika virus. First, they consulted with a hospital to identify all mothers who gave birth between 2015 and 2016. They then contacted each mother, obtained consent to participate in the study, and asked each mother whether her child was affected by microcephaly. Finally, they obtained maternal cellphone records for the 12 months preceding each birth and geocoded the data to describe each mother’s movements. The paper reported how proximity to known Zika hot zones was associated with an increased risk of microcephaly.
This study design is best described as (select one best answer):
a. Experimental study
b. Prospective cohort study
c. Retrospective cohort study
d. Case-control study
e. Cross-sectional study
f. Ecological study
Which of the following statements are NOT true? (select all that apply)
a. Randomized experimental studies ensure that provider preference and patient prognosis are not related to whether the study participant receives the treatment.
b. Cohort studies are the only study design with the ability to analyze multiple outcomes as they relate to an exposure.
c. When the prevalence of a disease is high, case-control studies are typically recommended.
d. Matching aims to select controls (free of the disease) that are comparable to cases (with disease) based on important variables that are not the exposure of interest in the study.
An investigator is interested in studying the relationship between average ambient air pollution in various cities on community cancer risk within these cities. Which study design does the investigator have in mind?
a. Prospective cohort study
b. Case-control study
c. Cross-sectional study
d. Ecological study