University of Western Sydney Epidemiology Assignment 1 - Autumn 2019

This document presents solutions to an Introduction to Epidemiology assignment from the University of Western Sydney. The assignment covers key epidemiological concepts including prevalence, incidence (cumulative and specific), and mortality rates. It includes calculations based on provided datasets, such as crude and age-specific rates, as well as direct standardized incidence rates. The assignment also explores different study designs, including cohort and case-control studies, examining their features, advantages, and disadvantages. Questions address research questions, study design identification, and the importance of standardization in data analysis. The solutions are presented in a clear and concise manner, providing detailed calculations and interpretations, offering a comprehensive guide for students studying epidemiology.

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The University of Western Sydney
School of Science and Health
Introduction to Epidemiology (401076)
ASSIGNMENT 1
Autumn, 2019
Due date: 7/04/2019 midnight
This assignment is based on the learning objectives and concepts in in weeks 1to 3
(not including measures of association). There are a total of 60marks and this
assignment will contribute 20% towards the total assessment for this subject.
Your assignment should be typed, with adequate space left between questions.
Assignments should be submitted via vUWS (see specific instructions relating to
Assignment 1 on vUWS).
Be as brief as possible in your answers, and use the number of marks for a question as
a guide to how much to write.
No answers need to be longer than a few short sentences or short paragraphs. No need
for referencing
Late assignments will not be accepted without prior approval. Any request needs
supporting documents.
Remember to save your assignment to make sure it is the final version and
submit only this. as:
Family name_First name_StudentID_Ass1_final
After due date I will not be able to remove the assignment. It is controlled by
Turnitin!!So the only version that will be corrected is the last one you submitted
before due date

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Question 1(14)
A rural community in Queensland was estimated to have a population of 73,000
during a census conducted on January 1st 2016. Of these, 3600 people were known to
have been diagnosed with type 2 diabetes before this day. During 2016, the entire
community was followed and 230 new cases of type 2 diabetes were diagnosed.
(a) “What was the prevalence of type II diabetes in this community on January 1st
2016?”[2 Marks]
3600
(b) “What was the prevalence of type II diabetes in this community on 30th of
December 2016?” [2 marks]
3600+230 =3830
(c) “What was the cumulative incidence of type II diabetes in this community
during 2016?” [4 Marks]
Cumulative incidence of type II diabetes 3830
“If during 2016 5,000 people from the entire community died and left the study area.
Assume that these 5000 people and the 230 new cases of diabetes were healthy at
least half of the year”.
(d) What type of incidence you need to calculate [2 Marks]
This is the total number of people affected with type II diabetes
(e) Calculate this type of incidence [4Marks]
Define the population at risk during this time = 73000- 5000 (5000 died)
Define the population at risk during this time =68000
Random sample from that population= 5230
Incidence = New ∧ pre existed casesoccuring during a given period of time
Population at risk at that same time

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Incidence = 3600+2300
68000
Incidence = 5900
68000
Incidence = 0.086764
Question 2:
“Data from HealthStats NSW (2015) are provided below. Use these data to answer
the following questions”.
Number of people with type 2 diabetes 756,507
Deaths from type 2 diabetes related causes 5,025
Death from all causes in NSW 49,607
Total population of NSW 9,006,043
a) Calculate all-cause mortality rate? [2 Marks]
All-cause mortality rate is obtained using the following formula,
All-cause mortality rate= all cause deaths
Total population × 100
All-cause mortality rate= 49,607
9,006,043 × 100
All-cause mortality = 0.5508%
(b) Calculate diabetes-specific mortality rate [2 Marks]
Diabetes-specific mortality rate =
Deaths ¿ type 2 diabetes related causes ¿
Number of people withtype 2 diabetes × 100
Diabetes-specific mortality rate = 5,025
756,507 × 100
Diabetes-specific mortality rate = 0.664%

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(c) Calculate diabetes case fatality rate?[2 Marks]
Diabetes case fatality rate=
Number of death due ¿ diabetes disease ¿
Number of cases of diabetes diseas ×
100
Diabetes case fatality rate= 5,025
5,025+756,507 × 100
Diabetes case fatality rate= 5,025
761532 × 100
Diabetes case fatality rate= 0.6598%
v

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Question3:
“The following table presents hypothetical data of the incidence of breast cancer in
women in two states (light grey City A- dark grey City B”
City A women
population
Number of
breast
cancers in
City B women
population
Number of
breast
cancers in
World
Standard
population
In 2010 2010 In 2010 2010
women
20-44 400,000 50 400,000 30 74,000
45-64 175,000 250 100,000 100 19,000
65+ 125,000 350 10,000 500 7000
100,000
(a) “Calculate the crude rates of breast cancer per 100,000 women in each city.
Compare the results.” [2 marks]
City A
Crude rates of breast cancer= Number of cancer ∈ city A
Women Total population of women∈city A × 100,000
.
Crude rates of breast cancer= 650
7 0000 × 100,000
Crude rates of breast cancer= 92.857
So it hence means there are 92 women for every 100000 living in city A suffer from
cancer.
City B
Crude rates of breast cancer= Number of cancer ∈city B
Women Total population of women∈city B × 100,000
.
Crude rates of breast cancer= 63 0
510000 × 100,000
Crude rates of breast cancer= 127.857
So it hence means there are 127 women for every 100000 living in city B suffer from
cancer.

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(b) Calculate the age –specific rates in community A and Community B per
100,000 women and summarise the resultssuccinctly [2 marks]
For CITY A
Age –specific rates= Cases of breast cancer ∈a specific age group
population∈the age group × 1000000
For age group 20-44
Age –specific rates= 50
400000 × 1000000
Age –specific rates= 12.5
For age group 45-64
Age –specific rates= 250
175000× 1000000
Age –specific rates= 142.8
For age group 65+
Age –specific rates= 3 50
125000 × 1000000
Age –specific rates= 280
FOR CITY B
Age –specific rates= Cases of breast cancer ∈a specific age group
population∈the age group × 1000000
For age group 20-44

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Age –specific rates= 3 0
400000 × 1000000
Age –specific rates= 7.5
For age group 45-64
Age –specific rates= 10 0
100 000× 1000000
Age –specific rates= 100
For age group 65+
Age –specific rates= 5 00
10 000× 1000000
Age –specific rates= 500 0
(c) “Calculate the direct standardised incidence rates of breast cancer for women
living in city A and in city B according to the world standard population
(given in the last column).Compare the two results and interpret your
findings.”[4 marks]
FOR CITY A
ts = ∑
a
(ta × Pa)
Where ts is the standardized rate, Pa is the proportion of standard population for city
A and ta is a proportions dying in city A
ts = ∑
a
(650 ×100000)
ts= 650 00000
FOR CITY B

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ts = ∑
a
(ta × Pa)
Where ts is the standardized rate, Pa is the proportion of standard population for city
A and ta is a proportions dying in city A
ts = ∑
a
(63 0 ×100000)
ts= 63 000000
d)”Based on the data you have just calculated would you say that standardisation was
important to understand the differences in breast cancer between the two cities?
Justify”[4marks]
Yes, it was important since it help to notice just from sight that breast cancer was
more in city A as compared to city B
.
.
Question 4 [4 Mark]
The number of people with a disease within the community increases when
a. Incidence rate < death rate + cure rate
b. Incidence rate < prevalence rate < death rate + cure rate
c. Prevalence rate = death rate + cure rate
d. Incidence rate > death rate + cure rate
Incidence rate > death rate + cure rate
Question5:
“Questionnaires were mailed to every 10th person listed in the city telephone
directory. Each person was asked to list age, sex, smoking habits, and respiratory

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symptoms during the preceding 7 days. Over 70% of the questionnaires were
completed and returned. It was found that 20% experienced upper respiratory
symptoms.
a) What was the research question? [2 Marks]
The research question in this Questionnaire is what are the incidence, distribution, and
possible control of diseases and other factors relating to smoking habits and the
symptoms of respiratory diseases.
b) What is the study design? [2 Marks]
Study design is actually a formulation of experiments, observations as well as trials
studies in clinical and medical research (for instance epidemiology) and this must
involve human beings.
c) What are the most important features of this study design [2 Marks]
This type of study design is Cohort Study (Prospective Observational Study)
(Temmerman, 2016). Its most important feature is that the investigators identifies
subject at a specific time if they do not have the outcome of the interest then they
compare when they have no outcome of interest in a group of people exposed
(Assembly, 2011).
Question6:
“1500 people aged 70 years and over were randomly selected from the NSW electoral
roll and were invited to participate in falls prevention study. Those who agreed to
participate were asked about their history of falling any disability that prevent them
from walking as well as about their exercise habits. They were asked about the types
of activity they do, the frequency per week and the number of hours they devoted to
the exercise every week. Researchers contacted each participant every 3 months
asking if they had a fall during this period and asked to describe the consequence of
the fall. They repeated these periodical calls every 3 months over two years. At the
end they compared the incidence of falls by four activity types and by duration per
week they did this activity”.
a) “What is the research question or hypothesis that the study attempt to answer
“(no more than 30 words)[2marks]
Is exercise good for the lives of aged people (of 70 years and above)? And can
doing exercise make the aged people to be strong.
b) “What study type/design the paragraph described and why do you think this is
the type (in other words justify your answer from the text, no more than 60
words!!)”[4 marks]:

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The study type is Randomized Controlled Trial (Pedley, 2012). This is because
exercise is employed to check if it can help in the prevention of any acute disease as
it was checked against the falls in these 70 + years old people.
c) “Describe the similar research question/s, but in a different study design”[ no
more than 100 words] [ 4 marks]
2000 people aged 70 and above were interviewed about how frequent they eat fruits
and vegetables. The interview was done weekly for a period of about 1 year. They
were ask the ratio of the vegetable and fruit to the canned food and red meet they take
(Merril, 2013). The result obtained were used to check the health of these two group
of people who mostly take vegetable and fruit against those who take canned food and
red meet. Their health was check on how frequent do they get sick and go to the
hospital.
Question7:
“100 patients with infectious hepatitis and 100 neighbourhood healthy control were
questioned regarding a history of eating raw clams or oysters within the preceding 3
months.”
a) “What is the study type/design”[2Marks]:
Case-control Study. This is because the healthy individuals were used to compare the
sick individual of the same number on the possible causes of the hepatitis.
b) “what were the key features in this text that assist you in deciding that this is
the design [2Marks]
This is because the healthy individuals were used to compare the sick individual of
the same number on the possible causes of the hepatitis. Some of the possible reason
for the prevention of this disease was eating raw clams and oyster.
c) “What are the advantage /disadvantage of using this design? “[2Marks]
Advantages

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i. This design is efficient for rare disease having longer latency period
between the disease and exposure.
Disadvantage
This design is subjected to bias in selection
d) “What could be the research question or hypothesis of this study ”[2 Marks]
The hypothesis here is that Eating both oyster and raw clams help to fight hepatitis

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Bibliography
Assembly, A., 2011. Health Care and Its Costs. 3rd ed. Stoke : The American
Assembly.
Merril, R., 2013. Introduction to Epidemiology. 1st ed. Chicago: Jones & Bartlett
Learning.
Pedley, T., 2012. The Epilepsies. 1st ed. Stoke: Elsevier Health Sciences.
Temmerman, M., 2016. Reproductive, Maternal, Newborn, and Child Health. 3rd ed.
Hull: World Bank.