PUBH7600 ASSESSMENT 1
Due Date: Monday 23 March, 2 pm (Qld time)
Complete the following short answer and calculation-based tasks.
• 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. This assignment will contribute 25% towards the overall assessment for this subject.
• For calculations, please show your formulae and 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 places e.g. if your calculated answer is 12.345, please round your final 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 number of marks and suggested length of response for a question as a guide to how much detail is required. Answers should not be longer than a few short sentences or short paragraphs.
Once you have completed your assignment upload and submit it for marking through the Turn-It-In link on Blackboard by 2 pm on 23 March 2020.
Some questions in this assignment are related to exploring chronic kidney disease in Aboriginal and Torres Strait Islanders, referred to in this assignment as Indigenous Australians. In acknowledging the diversity of Aboriginal and Torres Strait Islander peoples, please note the use of “Indigenous” is as a collective term that encompasses but does not attempt to homogenise the many distinct and unique countries, cultures and identities of Australia’s First Nations people.
One of the risk factors, which may contribute to the disparities in chronic kidney disease observed between Indigenous and non-Indigenous Australians, is acute post-streptococcal glomerulonephritis (APSGN). APSGN is a condition that occurs around 2-3 weeks after a skin or throat infection with some strains of group A streptococcus bacteria, that can cause high blood pressure and acute kidney failure (Centre for Disease Control, 2010). While APSGN is uncommon in the general Australian population, the incidence of APSGN in the Northern Territory of Australia is among the highest in the world (Marshall et al., 2011).
Centre for Disease Control (2010) Northern Territory guidelines for acute post-streptococcal glomerulonephritis. Casuarina: Department of Health and Community Services, Northern Territory Government.
Marshall CS, Cheng AC, Markey PG, Towers RJ, Richardson LJ et al., (2011) Acute post-streptococcal glomerulonephritis in the Northern Territory of Australia: a review of 16 years of data and comparison with the literature. American Society of Tropical Medicine and Hygiene; 85(4):703-710.
Researchers in the Northern Territory wanted to investigate the association between APSGN and chronic kidney disease in Indigenous Australians from the Northern Territory. The researchers recruited 350 Indigenous Australians with chronic kidney disease (aged 35 years and over) from a specialist clinic in Darwin (the capital city of the Northern Territory). This specialist clinic sees patients with chronic kidney disease from all over the Northern Territory. In order to do a comparison, they also recruit 350 participants who do not have chronic kidney disease. All participants were asked questions about their history of APSGN (using both self-report and past medical records).
Of the 350 participants who had chronic kidney disease, 192 had previously been diagnosed with APSGN at least once and 158 did not have a history of APSGN. Of those who did not have chronic kidney disease, 94 were identified as having a history of APSGN.
a) What type of study design is this study? Please justify your answer in 1-2 sentences [1 mark]
b) In your own words, what are some of the key advantages of this study design compared to a prospective cohort study? [1 mark]
c) If you were carrying out this study, describe where you would select an appropriate comparison group (i.e. those without chronic kidney disease) from? Be specific in describing the type of people you might include and where you recruited them from, justifying why these characteristics are important from a study design perspective (1-2 paragraphs) [2 marks]
d) Construct a 2x2 table conveying information from the study described above and calculate an appropriate measure of the strength of the association between APSGN and chronic kidney disease [3 marks]
e) How would you interpret your finding in Q1d? (1-2 sentences) [1 mark]
f) Calculate the attributable fraction of chronic kidney disease that is associated with APSGN [2 marks]
g) How would you interpret the finding in Q1f? [2 marks]
h) The group of researchers from the Northern Territory wanted to compare their study results with other studies published in the literature. They came across another study with the following results:
Number with Chronic Kidney Disease Person-years at risk
Previous APSGN 70 195,000
No history of APSGN 30 225,000
What type of study design was this data most likely from? Please justify your answer in 1-2 sentences [1 mark]
i) How does the strength of association found from the Northern Territory study compare to the strength of association from the study described in Q1h? Use any relevant calculations to justify your answer. [Use up to 1 paragraph for discussing your findings] [2 marks]
j) Based on the data from Q1h, how many cases of chronic kidney disease (per 100,000 person- years) in the total study population can be attributed to APSGN? [3 marks]
k) Is the measure of association that you calculated in Q1j better described as a risk difference or a rate difference? Please justify your answer [Use 2-3 sentences for discussing your findings] [2 marks]
l) The researchers have collated information from other Northern Territory studies on different risk factors for chronic kidney disease (such as high blood pressure, diabetes, rurality etc). They would like to identify what risk factor is responsible for the biggest burden in their population, so they can design an intervention with the biggest potential impact. What epidemiological measure of association would be the most useful to calculate? Please justify your answer [Use up to 1 paragraph for discussing your findings] [2 marks]
In the year 2005, a group of 8,000 adult residents of an island community in the Pacific Region were assessed for diabetes. One-fifth of the participants were smokers, the rest non-smokers (please assume that their smoking status does not change over time. Among the non-smokers, 624 persons were found to have diabetes while 256 smokers had diabetes at base-line. Participants were followed-up and assessed again in 2010 (only those who did not have diabetes at baseline were examined again at followup). A further 223 persons were identified as having diabetes at the follow-up assessment in 2010.
Data from this study are presented in the following table, stratified by smoking status.
No. of participants recruited Prevalent cases of diabetes at baseline Prevalent cases remaining at followup* Person years of followup** Loss to followup in those negative for diabetes at baseline Deaths in those negative for diabetes at baseline Incident cases of diabetes
Non-smokers 6,400 624 523 35,984 1146 614 160
Smokers 1,600 256 215 5,056 424 220 63
Total 8,000 880 738 41,040 1570 834 223
* It is assumed that once participants developed diabetes they continue to suffer from diabetes, and that over the follow-up period some of cases detected at baseline were lost to follow-up.
**The number of person-years in the table is equivalent to the total number of person-years at risk
(therefore there is no need to adjust this figure for losses to follow-up)
a) The prevalence of diabetes in all participants in 2005 [1 mark]
b) The prevalence of diabetes in non-smokers in 2010 [1 mark]
c) The cumulative incidence of diabetes in non-smokers over 5 years [2 marks]
d) The incidence rate of diabetes in non-smokers for the 5 years. [2 marks]
e) Assuming that the incidence rate of diabetes remains constant, what should happen to the prevalence of diabetes in this cohort over time? Please justify your answer. [Use up to 1 paragraph for discussing your findings] [3 marks]
Researchers investigated whether alcohol intake is associated with risk of head and neck cancers in women. They also wanted to know whether alcohol consumption had a greater impact on the development of head and neck cancers or breast cancers. To achieve this they carried out a study with a prospective design, in which they followed-up a cohort of women for 5 years. At the start of the study (baseline) it was assessed whether the women drank alcoholic drinks, and throughout the follow-up it was ascertained which of the women developed cancer.
In the low alcohol group 174 women developed head and neck cancer in 23,800 person-years of observation, while in the high alcohol group 126 women developed head and neck cancer in 4,200 person-years. Breast cancer was diagnosed in 710 women with low alcohol intake who contributed 22,100 person-years of observation, while in the high alcohol intake group 290 women developed breast cancer in 3,900 person-years of observation. [Note that person-years of observation are different for the two cancers, because a woman who develops breast cancer is still at risk of head and neck cancer and vice versa.)
********Please show details of your calculations to make clear which data you are using***********
a) Draw up a table from these data and calculate the Incidence Rates for each sub-group of alcohol intake for both cancer types. [2 marks]
b) Calculate the relative risk for high compared to low alcohol intake for both cancer types [2 marks]
c) Calculate the attributable risk due to high alcohol intake for head and neck cancers and breast cancers in this cohort of women. [4 marks]
d) How do you interpret the relative impact of high alcohol intake on the occurrence of head and neck cancer vs. breast cancers by using the attributable risks calculated in 3c? [Use 2 to 3 sentences for discussing your findings] [2 marks]
e) Calculate the proportion of head and neck cancers and breast cancer that are attributable to high alcohol intake among Australian women, and interpret your findings and their relevance to cancer prevention efforts. [Use up to 1 paragraph for discussing your findings] [3 marks] QUESTION 4
This question relates to the following table of deaths from ovarian cancer and breast cancer in Queensland and Australian females.
Age groups Ovarian cancer deaths QLD females Breast cancer deaths QLD females Female population
(QLD) Female population
0-19 0 0 713,600 3,867,510
20-49 19 31 1,198,847 6,302,609
50-64 99 246 456,704 2,578,340
65-74 203 338 313,984 1,145,929
75+ 320 409 171,264 429,723
a) The crude mortality rate for ovarian cancer in Queensland females [1 mark]
b) The crude mortality rate for breast cancer in Queensland females [1 mark]
c) The direct age-standardised mortality rate for ovarian cancer among Queensland women using the Australian female population as the standard [3 marks]
d) The direct age-standardised mortality rate for breast cancer among Queensland women using the Australian female population as the standard [3 marks]
e) What does the difference between the crude mortality rate and age-adjusted mortality rate for ovarian and breast cancer tell us? [Use up to 1 paragraph for discussing your findings] [3 marks]
END OF ASSIGNMENT