SPH 696 Epidemiology Methods Case Study 2022

Final Exam Name: ____________________
SPH 696 Epidemiology Methods II
Dr. Roman Pabayo
Part One: 40 marks
1. On January 28, 2020, Canada's first case of a novel coronavirus was identified and confirmed.
As of April 3, 2020, there are around 20,000 cases and 177 deaths. The Public Health Agency of
Canada has hired you to identify potential risk factors for deaths due to coronavirus infection.
How would you investigate this pressing public health emergency? You can make reasonable
assumptions.
Retrospective cohort study
- cohort studies allows for the investigator or to identify subjects at a point in time when
they have negative interests outcome and makes the comparison of incidence of the
outcome of interests among the exposed and non exposed groups. Cohorts can be
identified retrospective or prospectively, however in either case they need to be
established at two times. There is need for a consideration that cohort did have Covid -19
outcome at the beginning of the observation and need to observed if the outcome disease
developed later through assessment of incidence in each groups of study.
- Retrospective study compares the exposure status and makes a comparison based on the
disease incidence levels, in this case the status of the exposure and outcome are
ascertained in a retrospective manner.
- In this process, identification of a useful cohort which is free from a disease and is at
risks is selected. The records applicable in this will least’s say travel history of the cohort
individuals, assessment of each subject exposure status at the beginning of observation
period and then assessment of the subjects encounters in the two groups.
2. Data analysis
- In this study design, essential data tools which will be employed d entailed incidence
assessment of the disease, relative risks or risk ratios of developing the disease, risks
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Final Exam Name: ____________________
SPH 696 Epidemiology Methods II
Dr. Roman Pabayo
difference between the two groups and attributable proportion leading to deaths of the
disease in both the groups and disease occurrence.
- When the risks of the two groups are different, then we affirm that there is no association
between the disease and exposure state, while if the risks of the disease are higher or
lower in the exposed group then we make a conclusion that exposure is associated with
the covid -19 occurrences among the subjects.
3. Sources of bias, distortion or any other limitations.
- Cohort studies have inherent advantages; they provide clarity on temporal sequence.
They clearly indicate the temporal sequences occurring between the exposure and
outomce, due to the fact that cohort are known to be disease free at start of the
observation when the status of exposure is being established.
- Further cohort studies allows for calculation of incidences of diseases between the
groups. In this case fundamental measures entail absolute risks-incidence, risks ratio,
risks differences and attributable risks % of the disease.
- Cohort studies are essential in allowing multiple effects selection and examination of a
single exposure.
- Selection bias can be observed in this case since the otuomces already might have been at
different times.
- The usage of record in this design is crucial. Usage of record not for the design of the
study makes the data obtained to be of poor quality. Further, there is often the absence of
potential confounding factors if the data was obtained in the past. Further it has been
observed that it can be a challenge to identify the correct exposed cohort and appropriate
comparison group, however in this case the Covid 19 victims are available and easily
traceable. In large cohorts loss to follow up can occur such as death occurrences as
observed din this case there high mortality rates thus can hinder this process leading to
bias retrospective assessment.
(Supino & Borer,2012; Gallin & Ognibene, 2012)
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Socio-
demographic
characteristic
s
MortalityPolitical party
affiliation and
political
ideology
Moderates
Conservatives
Republicans
Final Exam Name: ____________________
SPH 696 Epidemiology Methods II
Dr. Roman Pabayo
Part Two: 20 marks
The following questions 1-5 are based on information from the article “Political Party
Affiliation, Political Ideology and mortality.”
4. Main exposure(s), outcome and a conceptual model
Exposures = political party affiliations and self-reported happiness and self-rated health
Outcomes = time to death and political beliefs and time to death
Conceptual framework
5. The authors argue that this article is a longitudinal study. Do you agree? Because ;
- The study is a longitudinal study bearing in mind the subjects were followed from the
year 1976 until the year 2008, this enabled a prospective assessment of political party
affiliations and risks of mortality rates among the subjects over these years.
- In essence, a longitudinal study is a research design study that observed represented
variables especially people over a long period to assess the underlying n measures being
of the study.
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