PUBH7600 Introduction to Epidemiology

Semester 1, 2025

ASSESSMENT 1

Due Date: Monday 31 March, 2 pm (QLD time)

Instructions:

Complete the following short answer and calculation-based tasks (Q1 to 4, including all the sub-questions).

• This assessment is based on the learning objectives and concepts from Modules 1-3 and the required readings. The data presented in this assessment is from both real and hypothetical sources.

• The value of the marks of each question is shown alongside the corresponding question. There are 50 marks in total, and this assignment will contribute 25%   towards the overall assessment for this subject.

• For calculations, please show your formulae and full working for calculations

(not simply the final answer), as you will receive part marks for applying the correct formula, even if you do not arrive at the correct answer.

• When performing calculations, please do NOT round numbers until the final answer is reached to avoid compounding errors due to early rounding. Please round all final answers to 2 decimal points. E.g., if your calculated final answer is 12.345, please round your answer to 12.35.

Your assignment should be typed as a Microsoft Word document, with adequate space left between questions. Be as succinct as possible in your answers and use the numbers of marks and suggested lengths of response for a question as a guide to how much detail is required.

Question 1 (17 marks)

Background

Immigration present unique health challenges as changes to dietary patterns can significantly impact cardiovascular outcomes among migrant populations. Researchers conducted a study investigating the relationship between dietary acculturation and hypertension among first-generation immigrants in an urban Australian community. The study aimed to understand  how the adoption of Australian dietary patterns influenced cardiovascular health outcomes among immigrants who had lived in Australia for less than 5 years at baseline.

The study enrolled 3500 adults aged 40-45 years and followed then from January 2014 to December 2023. At the enrolment, all participants underwent comprehensive health assessment, which identified 421 individuals with existing hypertension.

During the study period, the investigators faced several challenges in maintaining the study population. By the end of the study:

•    180 participants had relocated to different cities and were lost to follow-up despite multiple contact attempts

•   95 participants had died

•   249 new cases of hypertension were diagnosed.

(a)What is the study design used in this study? Justify with your own words [2-3 sentences, 1 mark]

(b)What was the prevalence of hypertension at the beginning? [show formula and working; 2 marks]

(c)What was the prevalence of hypertension at the end of the study? [show formula and working; 2 marks]

(d) What was the cumulative incidence of hypertension for this study? [show formula and working; 2 marks]

(e) What is the person–years at risk of hypertension? [show formula and working; 2 marks]

(f) What was the incidence rate of hypertension for this study period? [show formula and working; 2 marks]

(g) Explain the difference in calculation of cumulative incidence and incidence rate. [2-3 sentences, 2 marks]

(h) Consider the aim of study and population, which disease measure would help the investigator most and why? Include your calculated results in your explanation. [1 paragraph; 4 marks]

Question 2 [Total 8 marks]

Background

In early March 2024, a Municipal Public Health Centre in Western Japan received an unusual increase in reports of oedema, headache, fatigue, nausea, palpitations, and/or dizziness from several clinics. The initial investigation revealed that within a two-week period, 15 previously healthy adults had been hospitalised with severe acute kidney injury (AKI) of unknown origin. Preliminary patient interviews suggested a possible connection to dietary supplements marketed for weight loss. These interviews revealed that many affected individuals had purchased supplements through online platforms or drug stores in the preceding months.

As reports continued to emerge the health centre established an illness investigation team.

The team conducted a survey with 150 individuals who had purchased supplements in the past month, collecting information about their supplement consumption patterns and whether they had experienced AKI (Table 1).

Table 1:  Data collected by investigators exploring link between dietary supplements and acute kidney injury

(a) What is the study design used in this study? Justify with your own words [1-2 sentences; 1 mark]

(b) Calculate attack rates for each suspected item. [show formula and working; 3 marks]

(c) Based on the data presented in the table, which supplement shows the strongest association with AKI? Justify your answer with the attack rates you calculated in previous question. [3-4 sentences; 2 marks]

(d) Do you think this is the best way to investigate the source of outbreak? Why or why not? [2-3 sentences; 2 marks]

Maternal mortality rates have long been used as an important indicator to assess and compare healthcare systems across different countries. The United States reports higher rates of maternal deaths compared to other high-income nations, despite having advanced medical technology and significant healthcare expenditure.

A comparative analysis examined maternal mortality differences between the United States  and a number of other high-income countries.  The study utilised data from the U.S. Centers for Disease Control and Prevention (CDC) and the Organisation for Economic Co-operation and Development (OECD). Key data is displayed in Figure 1.

Figure 1: The maternal mortality ratio (maternal deaths per 100,000 live births) of high income countries compared to US populations.  Countries displayed include Norway Switzerland, Sweden, the Netherlands, Japan, Australia, Germany, United Kingdom, France, Canada, Korea, New Zealand, and Chile.

For more information: please refer to Munira Z. Gunja et al., Insights into the U.S. Maternal Mortality Crisis: An International Comparison (Commonwealth Fund, June 2024) https://doi.org/10.26099/cthn-st75

(a)  What does Figure1 tell us? What are some of the key determinants or factors that may be influencing this observation? [1 paragraph; 2 marks]

When examining US data in more depth the researchers found significant differences in the maternal mortality among Black non-Hispanic, White non-Hispanic, and Hispanic women.  Their initial working calculations are shown in Table 2.

Table 2: Calculations exploring US maternal mortality by race and age

Notes: Maternal mortality rate (MMR) was calculated as deaths per 100,000 live births. Expected deaths calculation used the White, non–Hispanic group as a standard population.

Using Table 2, complete the following calculations:

(b) Calculate the age-standardised maternal mortality rates for Black, non-Hispanic and Hispanic groups. [show formula and working; 2 marks]

(c)  What conclusion can be drawn about maternal mortality differences among race based on these standardised rates? [2-3 sentences; 2 marks]

(d) How does standardisation help us to compare maternal mortality rates between races? [2-3 sentences; 2 marks]

(e)  Identify potential issues that standardisation cannot address in this comparative analysis. What limitations or issues remain even after standardisation has been performed? [3-4 sentences; 2 marks]

Question 4 [Total 15 marks]

Background

Chronic Obstructive Pulmonary Disease) (COPD) ranks as the world's third-leading cause of death, with 3.3 million deaths recorded in 2019. The disease's impact is particularly severe in low-income and middle-income countries (LMICs), which experience 90% of COPD-related deaths. In Peru, it is unclear how geographic and social diversity affects the incidence of

COPD. Investigators conducted research on COPD across four rejoins of Peru with varying urbanisation levels, altitude, and biomass fuel use patterns. They recruited individuals with  COPD. Then they identified people who matched with age, sex and SES (social economic status) characteristics without COPD from same regions.

All participants completed a questionnaire collecting information about socio-demographic  factors, smoking history, respiratory symptoms, past medical history, biomass fuel exposure (frequency and duration) and family history of disease.  Initial study results are presented in tables 3 and 4.

a)  What type of study design is this study? Justify your answer [1-2 sentences; 1 mark]

b)  What are the advantages and disadvantages ofthis type of study design? [List; 2 marks]

Table 3: Incidence of COPD among biomass fuel users in Peru

Table 4: Incidence of COPD among smokers in Peru

Use the results in table 3 and 4 to answer the following questions:

c)   How many times as likely was a smoker to develop COPD than a non-smoker? [show formula and working; 1 mark]

d)  How many times as likely was a biomass fuel user to develop COPD than a non-biomass fuel user? [show formula and working; 1 mark]

e)  Among smokers with COPD, what proportion of their disease burden can be linked to their smoking status?  [show formula and working; 2 marks]

f)   Among the biomass fuel users with COPD, what proportion of their disease burden can be linked to their biomass fuels use? [show formula and working; 2 marks]

g)  To inform. local public health policy the Peruvian government would like to know the proportions all the COPD that occurred in the population that could have been avoided if no-one was exposed to the key exposures. Calculate appropriate measures for smoking and biomass fuel use [show formula and working; 2 marks].

h)  Write a short explanation to inform. the stakeholders of what your calculation results mean (2-3 sentences – 2 marks).

i)   What are the pro and cons ofthis type of calculation for decision making. [list - 2 marks]