PUB210 Task 2 Problem based short answer questions

PUB210 Task 2: Problem based short answer questions,

Task 2 is regarding Modules 1 to 6. The value of each question is shown beside the question.

You should attempt to answer all ten questions and each part of each question. For answers that involve calculations, show your workings as well as your final answer. If your final answer is incorrect but aspects of your approach are correct, your answer may still attract marks. Similarly, providing your rationale for answers that do not involve calculations may attract partial marks.

Please submit your answers when completed electronically via SafeAssign. This is an individual assignment that is to be completed independently.

1. What effect would each of the following have on (i) the incidence rate, (ii) the prevalence and (iii) the duration of the disease? Please include your reasoning. Please note that you are required to provide responses to i), ii) and iii) for each of (a), (b) and (c) below.

(a) The introduction of a new drug that cures a previously incurable but non-fatal non-communicable disease (1 mark)

1. incidence rate
2. prevalence

iii. duration of disease

 (b) The introduction of a new drug that prolongs survival but does not cure a fatal non-communicable disease (1 mark)

1. incidence rate
2. prevalence

iii. duration of disease

 (c) The introduction of a new vaccine that prevents most people from developing a disease. Vaccinated people who still develop the disease recover more quickly than unvaccinated people.  (1 mark)

1. incidence rate
2. prevalence

iii. duration of disease

2. In January 2006, 6,500 men aged 45-54 years joined a new health insurance plan and were offered a free health check. 3,400 of the men were found to be overweight or obese. Ten years later the men were checked again and 1,000 men who were healthy weight in 2006 were now overweight or obese, while 200 of those who were overweight or obese in 2006 had lost weight and were now in the healthy range. None of the men were underweight in 2006 or 2016.

(a) What was the prevalence of overweight and obesity in the men in: (1 mark)

1. January 2006 and
2. January 2016?

(b) What was the incidence proportion for becoming overweight/obese in the men who were healthy weight in 2006?  (1 mark)

(c) What was the incidence proportion for becoming healthy weight among the men who were overweight or obese in 2006?  (2 marks)

 

3. A health department was notified of an outbreak of gastroenteritis among guests who had attended a party. Everyone who attended the party was interviewed by the outbreak investigation team, which included an epidemiologist. They were asked about the foods they had consumed at the party and whether or not they had become ill. The following information was obtained:

A total of 300 guests attended the party and all were interviewed. Of these 200 had developed gastroenteritis in the 24-hour period following the party.

The number of people who ate each of the three main foods at the party is shown below.

Ate	Sick	Not sick
Chicken	140	90
Salad	190	85
Coleslaw	160	30

 

1. What is the absolute risk (or probability) that a person developed gastroenteritis after eating?

(1 mark)

1. Chicken
2. Salad

• Coleslaw

1. Construct a 2X2 table for exposure to coleslaw and the outcome of gastroenteritis for the 300 people who attended the party (2 marks)
2. What is the relative risk of illness among those who ate coleslaw compared with those who did not? (1 mark)
3. Write a conclusion about the association between consuming coleslaw and developing gastroenteritis among the group of party attendees (2 marks)
4. A study compared personal income and highest educational qualifications attained in council areas of Australia. Results are shown in the graph below.

(a) Describe the results shown in the figure.  (1 mark)

(b) What type of study is this?  (1 mark)

(c) How convincing are the data for evaluating whether attainment of a Bachelor degree or higher educational qualification leads to a higher income?  (2 marks)

5. A case-control study examined the relationship between consumption and oily fish high in omega-3 fatty acids (e.g. sardines) and coronary heart disease.

	Coronary heart disease
Weekly oily fish consumption	Yes	No
< 1 meal	125	175
> 1 meal	75	225

 

1. Calculate the odds that: (2 marks)
2. A person with coronary heart disease had consumed < 1 oily fish meal per week?
3. A person without coronary heart disease had consumed < 1 oily fish meal per week?
4. Calculate the odds ratio (OR) for the association between exposure to < 1 oily fish meal per week and the outcome of coronary heart disease (1 mark)
5. What does the OR mean? Report your conclusion (2 marks)

6. You want to conduct research to discover the cause/s of a newly-identified condition that has severe outcomes, currently has no cure and has been reported to affect 50 children in Australia last year.

(a) What study design would you use to answer the question and why? (1.5 mark)

• Who would you include in the study and why? (1.5 mark)

7. In a case-control study looking at the relationship between having freckles and risk of melanoma, 136 of 183 cases and 61 of 183 controls had freckles.

(a) In this group, what was the odds ratio for melanoma and having freckles? Interpret this odds ratio.  (2 marks)

(b) Estimate the attributable fraction of having freckles for melanoma. Interpret this estimate, including relevant assumptions. Explain why an estimate of the attributable fraction is used. (2 marks)

8. Is it correct to interpret an incidence rate ratio of 10 as being a high risk for disease in the exposed? Why or why not? Provide an example to illustrate your point. (2 marks)

9. A large hypothetical study assessed the association between average daily hours using electronic media (i.e. ‘screen-time’) at eight to ten years of age and the incidence of sight problems as a teenager. In children for whom low levels of screen-time were reported, there were 1,318 incident cases of sight problems during 280,364 person-years of follow-up. In children with intermediate levels of screen-time there were 3,070 cases in 436,372 person-years, and in children with the highest levels of screen-time, there were 4,104 cases in 407,193 person-years of follow-up.

(a) Calculate the incidence rate of sight problems as a teenager overall and among children who had each level of screen-time as an eight to ten year-old child.   (2 marks)

(b)  How strong is the association between screen-time as an eight to ten year-old child and incidence of sight problems as a teenager?  [Note: Assume that the results cannot reasonably be explained by the alternative explanations of bias, confounding or chance.] (2 marks)

(c)  What proportion of sight problems could theoretically be prevented if all children had low levels of average daily screen time?   (2 marks)

10.

(a) We conduct a study on the Sunshine Coast investigating whether high levels of community disadvantage lead to walking on average at least one hour per day. The relative risk is 1.5 with a 95% confidence interval of 1.2-1.9. Interpret this result, including the confidence interval. (1 mark)

• We then conduct a similar study on the Gold Coast and get a relative risk of 3.0 with a 95% confidence interval of 0.98-11.3. Interpret this result, including the confidence interval. (1 mark)
• Do neither, either or both of the two studies suggest that there is an association between community disadvantage and walking on average for at least one hour per day? Explain your answer. (1 mark)