PUBH7016_2023_Sem1_Assign1 (1)
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Health Science
Date
Nov 24, 2024
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docx
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Uploaded by ChiefLightning11606
ID
Western Sydney University
School of Health Sciences
Introduction to Epidemiology (PUBH7016)
ASSIGNMENT 1
Autumn, 2023
Due date: 9
th
of April, 2023 midnight
This assignment is based on the learning objectives and concepts learnt in the first 3
modules. There are a total of 58 marks (20 points for the quiz and 38points for the
scenarios) and this assignment will contribute 20% towards the total assessment for
this subject.
To complete this assignment you need to do a 30-minute quiz of 20 questions and
submit via Turnitin by the due date.
The answers to scenario based questions should
be typed in this document!,
Leave the question as it is – don’t erase it from the
document. Leave adequate space between questions.
Don’t erase quotation marks I used – this is done to reduce similarities as you all
answer the same questions.
Assignments should be submitted via vUWS Turnitin which was prepared for you in
assignment 1 tab.
Be as brief as possible in your answers. No answers need to be longer than a few short
sentences or short paragraphs.
No references are needed!
Make sure the way you reached the final answer is clearly detailed! All calculations
should be presented.
Save your assignment as:
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_
First name_StudentID_Ass1
Before the due date and time, you will be able to upload and download your
assignment as many times as you want, however, after due date the version that you
submitted will be locked by Turnitin and no one can remove it –
this will be the
version that will be assessed!
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make sure to save your final version on your
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ID
Remove this instruction page from the submission and sign and tick all the boxes in
the next page
ID
SCHOOL OF
ASSIGNMENT COVER SHEET
STUDENT DETAILS
Student
name:
Student ID
number:
UNIT AND TUTORIAL DETAILS
Unit
name:
Unit
number:
Tutorial group:
Tutorial day and
time:
Lecturer or Tutor
name:
ASSIGNMENT DETAILS
Title:
Length
:
Due
date:
Date
submitted:
Home campus (where you are
enrolled):
DECLARATION
I hold a copy of this assignment if the original is lost or damaged.
I hereby certify that no part of this assignment or product has been copied from any other
student’s work or from any other source except where due acknowledgement is made in the
assignment.
I hereby certify that no part of this assignment or product has been submitted by me in
another (previous or current) assessment, except where appropriately referenced, and
with prior permission from the Lecturer / Tutor / Unit Coordinator for this unit.
No part of the assignment/product has been written/produced for me by any other
person except where collaboration has been authorised by the Lecturer / Tutor /Unit
Coordinator concerned.
I am aware that this work will be reproduced and submitted to plagiarism detection software
programs for the purpose of detecting possible plagiarism
(which may retain a copy on
its database for future plagiarism checking).
Student’s
signature:
Note:
An examiner or lecturer / tutor has the right to not mark this assignment if the above
declaration has not been signed.
Question 1:
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ID
“The following table presents hypothetical data of the mortality from disease Z in two
communities ( Community A and community B) for young and old people
Age Group
(yrs)
community A
community B
No. of
People
No. of Deaths
From Disease Z
No. of People
No. of Deaths From
Disease Z
45-65
8,000
69
5,000
48
65 plus
11,000
115
3,000
60
(a)
“Calculate the crude mortality rate of disease Z per 1000 people in each
community. Compare the results in your own words using rate ratio or rate
difference.” (you need to show all the calculation steps not just give the
correct answer) [
4 marks
]
Answer:
To calculate the crude mortality rate of disease Z per 1000 people in each community,
we need to divide the number of deaths from disease Z by the number of people and
then multiply by 1000. The calculations are shown below:
Crude mortality rate in community A = (69 + 115) / (8000 + 11000) * 1000 = 11.35
per 1000 people
Crude mortality rate in community B = (48 + 60) / (5000 + 3000) * 1000 = 15.00 per
1000 people
To compare the results, we can calculate the rate ratio or rate difference. The rate ratio
is calculated by dividing the crude mortality rate in community B by the crude
mortality rate in community A:
Rate ratio = 15.00 / 11.35 = 1.32
This means that the crude mortality rate in community B is 1.32 times higher than in
community A.
The rate difference is calculated by subtracting the crude mortality rate in community
A from the crude mortality rate in community B:
Rate difference = 15.00 - 11.35 = 3.65 per 1000 people
This means that the crude mortality rate in community B is 3.65 per 1000 people
higher than in community A.
(b)
Which community is older, justify by comparing the age distribution
[2
marks]
ID
Answer:
To compare the age distribution of the two communities, we can calculate the
proportion of people in each age group for each community:
Age Group (yrs) Community A Community B
45-65 8,000 / 19,000 = 0.42 5,000 / 8,000 = 0.63
65 plus 11,000 / 19,000 = 0.58 3,000 / 8,000 = 0.38
We can see that Community A has a higher proportion of people in the 65 plus age
group (58%) compared to Community B (38%), indicating that Community A is older.
(c)
“
Calculate the age-adjusted mortality rate for disease Z in communities A and
B
by the direct method, using both communities as the standard population
(i.e., sum the numbers in each age group in Community A and Community B
to create the standard population).
When you present the results, please make
sure the headings of columns and rows are clearly stated” [
4 marks
]
Answer:
For Community A:
Proportion of population in the 45-65 age group: (8,000 / (8,000 + 11,000)) = 0.421
Proportion of population in the 65+ age group: (11,000 / (8,000 + 11,000)) = 0.579
Expected deaths in the 45-65 age group: (0.421 * 69) + (0.579 * 115) = 93.3
Expected deaths in the 65+ age group: (0.421 * 0) + (0.579 * 60) = 34.7
Total expected deaths: 93.3 + 34.7 = 128
Age-adjusted mortality rate: 128 / (8,000 + 11,000) = 0.00886 or 8.86 per 1,000
For Community B:
Proportion of population in the 45-65 age group: (5,000 / (5,000 + 3,000)) = 0.625
Proportion of population in the 65+ age group: (3,000 / (5,000 + 3,000)) = 0.375
Expected deaths in the 45-65 age group: (0.625 * 48) + (0.375 * 60) = 50.4
Expected deaths in the 65+ age group: (0.625 * 0) + (0.375 * 115) = 43.1
Total expected deaths: 50.4 + 43.1 = 93.5
Age-adjusted mortality rate: 93.5 / (5,000 + 3,000) = 0.0117 or 11.7 per 1,000
The table below summarizes the results:
Community
Standard Population
Expected Deaths
Age-Adjusted Mortality
Rate
A
19,000 128
8.86 per 1,000
B
8,000
93.5
11.7 per 1,000
ID
(d)
“Would you say that age -standardisation influenced the conclusion we had
when we compared the crude rates? Justify your answer by referring to the
differences in the age profile of the two communities?”.
[4marks]
Answer:
Age-standardization adjusts for differences in the age structure of populations. In this
case, we see that community B has a higher proportion of older people compared to
community A. Without age-standardization, we might erroneously conclude that
community A has a higher mortality rate because it has more deaths overall. However,
age-standardization allows us to compare mortality rates between communities more
accurately by controlling for differences in the age structure. In this case, after age-
standardization, we see that community B actually has a higher age-adjusted mortality
rate than community A, which might suggest that community B has worse health
outcomes related to disease Z.
Question 2
Look at the figure below [
Source: Colli et al. Urologic Oncology 2005]
(a) What is the study type that generated this figure and what are the key features of
this study that led you to this choice?
(
not more than 60 words
)
[4 marks]
Answer:
The study type that generated this figure is a retrospective cohort study. The key
features of this study that led to this choice include the identification of a group of
patients with a specific disease (renal cell carcinoma) and the comparison of survival
outcomes between two exposure groups (patients with and without tumor thrombus).
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ID
(b) What is the research question behind this study? What is the main exposure? what
is the main outcome? and what is the message from this graph, in your own words?
[4 Marks]
Answer:
The research question behind this study is whether the presence of tumor thrombus in
renal cell carcinoma patients is associated with worse survival outcomes. The main
exposure is the presence of tumor thrombus, while the main outcome is overall
survival. The message from this graph is that patients with tumor thrombus have
significantly worse overall survival compared to patients without tumor thrombus.
(c) Do you think it is practical to design an experiment that tests the same research
question you mentioned above?
Justify your answer (
not more than 60 words
)
[4
Marks]
It is not practical to design an experiment to test the same research question in a
randomized controlled trial because it would be unethical to deliberately expose some
patients to a potentially life-threatening condition (tumor thrombus) in order to test
the effect on survival outcomes. Therefore, retrospective cohort studies or other
observational study designs are the most appropriate ways to investigate this research
question. However, future prospective studies could use standardized diagnostic
criteria to identify tumor thrombus and investigate potential treatments that may
improve survival outcomes for these patients.
ID
Question 3:
“An invitation for blood pressure measurements was sent to all middle-aged
employees of the Australia Post in NSW and 85% of those who received
invitations were checked for blood pressure. All those that had normal blood
pressure were emailed their results and recommend checking their blood pressure
every two years. Those with abnormal blood pressure were emailed the result and
were invited to take part in a study. Consenting individuals were randomly
assigned to Mediterranean diet group, which followed a 12-month program of this
diet, or to a control group, which received educational materials about healthy
lifestyle mailed to their addresses. Both groups were followed for recovery from
abnormal to normal blood pressure at 3, 6 and at 12 months from baseline”
a)
“
What study type/design the paragraph described and why do you think this
is the type (
justify your answer with no more than 60 words
!!)”
[4 marks]
:
Answer:
a) The study design described in the paragraph is a randomized controlled
trial. This is because the study involved randomly assigning participants to
either the Mediterranean diet group or the control group, and then following
both groups over time to measure the recovery from abnormal to normal
blood pressure.
b)
“What is the research question or hypothesis that the study attempt to
answer? what is the exposure factor and what is the outcome?“ (
no more
than 60 words
)
[4 marks]
Answer:
The research question of the study is whether a 12-month Mediterranean
diet program can lead to better recovery from abnormal to normal blood
pressure compared to receiving educational materials about healthy lifestyle.
The exposure factor is the Mediterranean diet program, and the outcome is
the recovery from abnormal to normal blood pressure at 3, 6, and 12 months
from baseline.
ID
c)
“What other study design you can consider for this research question and
explain why you chose it” (
no more than 100 words
)
[4 Marks]
Answer:
An alternative study design that could be considered for this research question is a
prospective cohort study. This would involve identifying a large group of middle-aged
employees and measuring their blood pressure at baseline. Participants could then
be followed over time to see whether those who chose to follow a Mediterranean
diet program had better blood pressure outcomes compared to those who did not
follow the program, while controlling for potential confounding factors such as age,
sex, and baseline blood pressure levels. However, this design may be less practical
and more prone to bias due to self-selection of participants.
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