Jacqueline - Task 7 (4)

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Georgia Southern University *

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Chemistry

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Jan 9, 2024

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Module 7 Task: Problem Set Name:____ Jacqueline C. Nduka __________________________ In a study of environmental chemical exposure and childhood asthma, the exposed group was comprised of 400 grade school children (asthma-free) living within a two-mile radius of a chemical manufacturing plant. These children received a physical examination at baseline and then annually for two years to record the occurrence of asthma. The unexposed 600 grade school children (asthma-free) are randomly selected from three surrounding counties where there are no manufacturing plants within 20 miles of their residence. These children also received a physical examination at baseline and then annually for two years to record the occurrence of asthma. At the end of the two-year follow-up period, 200 of the exposed children developed asthma and 100 of the unexposed children developed asthma. Asthma (D) No Asthma (D~) Total Live within a two-mile radius of a chemical manufacturing plan (E) 1. 200 2. 200 400 Do not live within a two-mile radius of a chemical manufacturing plan (E~) 3. 100 4. 500 600 Total 300 700 1,000 5. This study is a: 1

a. Retrospective cohort study b. Cross-sectional study c. Prospective cohort study d. Case-control study e. Clinical trial 6. Why?  This is a prospective cohort study because it involves following a group of initially asthma-free grade school children (both exposed and unexposed) over time to determine the development of asthma. The exposure (living within a two-mile radius of a chemical manufacturing plant) is identified at the beginning, and the occurrence of asthma is monitored prospectively. 7. What is the risk of developing asthma in the exposed group of children? 8. What is the risk of developing asthma in the unexposed group of children? 9. What is the risk ratio? 10. If the value of the risk ratio was 5.0, how would it be interpreted? a. Children living within a two-mile radius of a chemical manufacturing plant are 5.0 times more likely to develop asthma than children living outside a two-mile radius of a chemical manufacturing plant. b. The odds of living within a two-mile radius of a chemical manufacturing plant are 5.0 times higher among those children with asthma than those children without asthma. 2

c. The odds of having asthma are 5.0 times higher among those children living within a two-mile radius of a chemical manufacturing plant than those children not living within a two-mile radius of a chemical manufacturing plant. d. Children with asthma having a 5.0 risk of living within a two-mile radius of a chemical manufacturing plant. 11. Which observational study design is best for rare diseases? Why? (Choose from: Cohort study, Cross-sectional study, Case-control study, Ecologic study, or Clinical trial)  The case-control study design is often considered the best for investigating rare diseases. In a case-control study, individuals with the rare disease (cases) are compared to individuals without the disease (controls). This design allows for efficient investigation of the potential risk factors associated with the rare disease by comparing the exposure history of cases to that of controls. Given that the disease is rare, it's more practical to identify cases and then select appropriate controls to study the potential causes or risk factors. 12. Which observational study design is best for looking at multiple diseases? Why? (Choose from: Cohort study, Cross-sectional study, Case-control study, Ecologic or Clinical trial)  The cross-sectional study design is often most suitable for examining multiple diseases simultaneously. In a cross-sectional study, data is collected from participants at a single point in time or within a very short time frame. This design allows for the assessment of the prevalence of various diseases or health conditions within the studied population. It provides a snapshot of the population's health status, making it efficient for analyzing the occurrence of multiple diseases concurrently. However, it's important to note that cross-sectional studies provide a snapshot and cannot establish causation or temporality of the diseases. 13. Which observational study design is best for rare exposures? Why? (Choose from: Cohort study, Cross-sectional study, Case-control study, Ecologic study, or Clinical trial)  The case-control study design is the most suitable for investigating rare exposures. This design involves identifying individuals with the specific outcome or condition of interest (cases) and comparing their exposure history with that of individuals without the outcome (controls). For rare exposures, this approach is efficient and effective. By focusing on cases with the rare exposure and matching them with appropriate controls, researchers can study the association between the infrequent exposure and the outcome without the need for a large sample size. This targeted selection makes it a cost-effective and powerful tool for understanding the impact of rare exposures on specific health outcomes. 14. Which observational study design is best for diseases with long latency periods? Why? (Choose from: Cohort study, Cross-sectional study, Case-control study, Ecologic study, or Clinical trial) 3

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 The cohort study design is the most effective observational study design for diseases with long latency periods. Diseases with long latency periods often take years or even decades to manifest after exposure to a particular risk factor. A cohort study involves selecting a group of individuals based on their exposure to specific risk factors and following them over an extended period to observe and analyze the development of diseases or outcomes. This extended follow-up period is crucial for capturing the prolonged incubation period associated with diseases with long latency. Researchers can gather comprehensive data on exposures, lifestyle factors, demographics, and other relevant variables at the beginning of the study and then monitor the cohort over time. By assessing the incidence of the disease and comparing it to the initial exposures, researchers can establish a clear and robust association between the risk factor and the delayed development of the disease. The cohort study design's ability to track and analyze individuals over a long duration makes it the most suitable for understanding the delayed onset of diseases and establishing causal relationships between risk factors and long-term health outcomes. 15. Several researchers felt that a graduate degree increased one’s chances of developing prostate enlargement. A study was designed to test this belief. The investigators identified a group of 1,100 patients whose initial diagnosis on admission to the hospital was prostate enlargement. A group of 2,000 patients admitted to the hospital for non-prostate enlargement was ascertained as a control group. Of the patients identified on admission, 1,015 patients with prostate enlargement and 1,600 without prostate enlargement agreed to participate and were included in the study. Then the patients of both groups were interviewed to find out about their educational level. The interviewers did not know which patients had prostate enlargement and which did not. What type of study design is this? Why? (Choose from: Prospective cohort study, Retrospective cohort study, Historical prospective cohort study, Cross-sectional study, Case-control study, Ecologic study, or Clinical trial)  This study design is a type of cross-sectional study. A cross-sectional study collects data from participants at a single point in time or within a very short period, essentially providing a snapshot of a population or a specific group at that particular moment. In this case, the researchers interviewed patients with and without prostate enlargement to gather information about their educational level. The study is cross-sectional because it assesses both exposure (educational level) and outcome (prostate enlargement) simultaneously, without following the patients over time. The design allows for the evaluation of the relationship between educational level and prostate enlargement in a specific population at a specific point in time. The selection of participants from those admitted to the hospital, both with and without prostate enlargement, helps in comparing the educational levels between the two groups and examining the hypothesis that a graduate degree might increase the chances of developing prostate enlargement. 4

16. A study was done to examine the hypothesis that exposure to laboratory animals increases the risk of laboratory animal allergy (LAA). Two groups of workers employed at GlaxoSmithKline (GSK), a pharmaceutical company in North Carolina completed an in-person interview and questionnaire in 1991. Both groups were similar in terms of major risk factors of LAA. During 15 years of follow-up, 185 incident cases of LAA were diagnosed in the group not exposed to laboratory animals, so that a total of 142,140 person-years of follow-up time accrued. In the group with exposure to laboratory animals, a total of 265 incident cases of LAA occurred and 123,444 person-years accrued. Assume that the deaths were uniformly distributed during the follow-up period and no other losses to follow-up occurred. What type of study design is this? Why? (Choose from: Prospective cohort study, Retrospective cohort study, Historical prospective cohort study, Cross-sectional study, Case-control study, Ecologic study, or Clinical trial)  This study design is a type of retrospective cohort study. A retrospective cohort study looks back in time to establish a relationship between exposure to a particular factor and the occurrence of an outcome. In this case, the researchers initially identified two groups of workers, one exposed to laboratory animals and the other not exposed, and then looked back at their historical data from 1991. They assessed the exposure to laboratory animals at the beginning of the study and followed the participants for 15 years to observe the incidence of laboratory animal allergy (LAA). The study examines the relationship between exposure (to laboratory animals) and the subsequent development of LAA over the follow-up period. The data collected during the 15 years allowed the researchers to calculate incidence rates and person-years of follow-up for both groups, contributing to the retrospective cohort study's methodology. 17. Prior research has shown that individuals who are small at birth are at increased risk of ischemic heart disease (IHD) later in life. One hypothesis to explain this association is fetal adaptation to a suboptimum intrauterine environment. Therefore a study was conducted to test whether pregnancy complications associated with low birth weight are related to risk of subsequent IHD in the mother. In 2005, routine discharge data were used to identify all singleton first births in Scotland between 1981 and 1985. Linkage to the mothers' subsequent admissions and deaths provided 20–24 years of follow-up. What type of study design is this? Why? (Choose from: Prospective cohort study, Retrospective cohort study, Historical prospective cohort study, Cross-sectional study, Case-control study, Ecologic study, or Clinical trial)  This study design is a type of retrospective cohort study. A retrospective cohort study involves looking back at historical data to identify exposures or risk factors and then analyzing the outcomes that occurred after those exposures. In this case, the researchers identified a group of individuals (mothers) based on certain criteria (singleton first births in Scotland between 1981 and 1985) and gathered data on their pregnancy complications and birth outcomes. They then followed these 5

individuals over a 20–24 year period to observe the occurrence of ischemic heart disease (IHD) later in life. The data from routine discharge records provided a historical view of pregnancies and subsequent health outcomes, allowing the researchers to analyze the relationship between pregnancy complications, low birth weight, and the risk of IHD in the mothers. 18. A study was conducted in order to better understand the influencing factors of HIV infection among former commercial blood and plasma donors engaged in unsafe blood donation practices in China. Data about influencing factors from the past 5 years was obtained from ten counties (districts) from six provinces using a national blood and plasma donation database. A representative sample of donors was selected and data regarding HIV/AIDS infection, incidence, and death was collected over the course of 5 years. What type of study design is this? Why? (Choose from: Prospective cohort study, Retrospective cohort study, Historical prospective cohort study, Cross-sectional study, Case-control study, Ecologic study, or Clinical trial)  This study design is a type of retrospective cohort study. A retrospective cohort study involves looking back at historical data to identify exposures or risk factors and then analyzing the outcomes that occurred after those exposures. In this case, the researchers collected data from the past 5 years regarding influencing factors of HIV infection among former commercial blood and plasma donors engaged in unsafe donation practices in China. They selected a representative sample of donors from a national blood and plasma donation database and gathered data on HIV/AIDS infection, incidence, and death over the 5-year period. By analyzing this historical data, the study aims to understand the relationship between unsafe blood donation practices and HIV infection, making it a retrospective cohort study. 6

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