Communicable Disease 

PUB 210 Task 2: Problem based short answer questions,
1. What effect would the following have on (i) the incidence rate, (ii) the prevalence and (iii) the duration of disease, and why?  (3 marks)
(a) The introduction of a new drug that cures a previously incurable but non-fatal non-communicable disease
(b) The introduction of a new drug that prolongs survival but does not cure a fatal non-communicable 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.

2. In July 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 normal range. None of the men were underweight in 2006 or 2016.
(a) What was the prevalence of overweight and obesity in the men in (i) January 2006 and (ii) January 2016? (1 mark)
(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 of becoming healthy weight among the men who were overweight or obese in 2006?  (2 marks)

3. A media article reported an age-standardised incidence rate of 10 cases per 100,000 Sunshine Coast Council residents for a certain condition in 2016. Using an estimated population of 300,000 residents, the journalist concluded that there were 30 new cases of the condition in the Sunshine Coast Council area in 2016. Was this an appropriate conclusion? Why or why not?  [Note: Assume for this question that all cases are identified.] (1 mark)

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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.  (2 marks)
(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 higher income?  (2 marks)
(d) You are asked to design a study that is inexpensive, quick and would provide a more convincing assessment of this relationship. What study design would you recommend and why? (2 marks)

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5.  What study design would you choose to answer the following questions and why:  (4 marks)
(a) Is smoking associated with the risk of catching either influenza or the common cold in winter in Queensland?
(b) Does smoking affect the duration of the common cold?
(c) Is primary area of study (e.g. health, education, law, business) in undergraduate university students associated with current usual consumption of at least two serves of fruit each day?
(d) Which of two currently accepted and used methods to minimise a child’s pain during vaccination is more effective?

6. You want to conduct research to discover the causes of a serious, newly-identified condition that 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 mark)
(b) Who would you include in the study and why? (1.5 marks)

(c) Name some other critical features of the design or conduct of this type of study. (1.5 marks)

7. In a case-control study looking at the relationship between having freckles and risk of melanoma, 136 of 183 controls and 61 of 183 cases had freckles.
(a) If you have freckles how much more or less likely are you to develop melanoma than someone who does not have freckles?  (2 marks)
(b) Based on this study and assuming the results represent a causal association, what is the attributable fraction for having freckles and melanoma.  (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)

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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.] (3 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. We conduct a study on the Sunshine Coast investigating the association between high levels of community disadvantage and walking on average at least one hour per day and get an odds ratio of 1.5 with a 95% confidence interval of 1.2-1.9.
(a) What does this tell us about the association between community disadvantage and walking on the Sunshine Coast? (1 mark)

(b) We then conduct the same study on the Gold Coast and get a relative risk of 3.0 with a 95% confidence interval of 0.98-11.3. What does this suggest to us about the association between community disadvantage and walking on average at least one hour per day on the Gold Coast? (1 mark) (c) Do neither, either or both of the two studies – Sunshine Coast or Gold Coast – suggest that there is an association between community disadvantage and walking on average for at least one hour per day? Explain your answer. (2 marks)