2018_Spring_Assign2(2).doc

The University of Queensland
7
The University of Western Sydney
School of Science and Health
Introduction to Epidemiology (401076)
ASSIGNMENT 2
Spring, 2018
Due date: 30 September, 2018
This assignment is based on the learning objectives and concepts in weeks 1-7. There are a total of 70 marks and this assignment will contribute 30% 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 2 on the 401076 vUWS web-site). Be as
ief 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. Please note this is an individual exercise.
Late assignments will not be accepted without prior approval.
Read the following paper, and answer the questions below:
Sundquist K., Qvist J. Johansson SE., Sundquist J. The long-term effect of physical activity on incidence of coronary heart disease: a 12-year follow-up study Preventive Medicince 2005;41:219-225
Question 1
(a) What study design does this study employ? [1 mark]
Longitudinal Study Design, spanning for 12 year time period.
(b) What was the data source used to identify first event of Coronary Heart Disease? [2 marks]
Interviews of Random sample of men and women aged 35-74 years.
(c) Why the authors excluded 1894 participants who rated their general health as “poor” ? [2 marks]
Participants with poor health could not be monitored for longer period of 12 years and may not get involved in Leisure time physical activities.
(d) What was the crude overall incidence of CHD ? [2 marks]
63.54% (3302/5196 * 1000)
(e) Compared the relative risk of not doing any physical activity to that of “doing at least twice a week” i) low income ii) in all other ? [4 marks]
People who were physically active at least twice a week were at 41% lower risk of CHD. Increased physical activity reduced the incidence rate of CHD. The relative risk was same for both the low income and other groups of people.
(f) How would you interpret the relative risk in the above question (e)? [3 marks]
Relative Risk is the Number of respondents who followed leisure time physical activity for 12 years and had a positive impact on CHD.
(g) Is the relative risk for this study better described as a risk ratio or a rate ratio? Why? [2 marks]
The Risk of CHD in the physically active people needs to be compared to the risk in Hospitalized patients who are inactive, to measure the impact of physical activity on the incidence of CHD.
(h) What do you think would be the major confounders that were not considered in this study? To answer this question you need to read about what are the major classical risk factors for CHD [4 marks]
The respondents having Diabetes, High BP, high cholesterol, poor nutrition, and Hypertension might prove to be major confounders.
(i) Why do you think the author could not adjust for these confounders? Hint: think about the way this study was designed [4 marks]
The study was developed to focus on the level of physical activity in the respondents. It randomly selected the males and females of particular age group just excluding the old age people and ill diseased people who were admitted in the hospitals.
Question 2:
Tasmanian researchers conducted a case –control study to investigate the effect of dietary fat intake on melanoma (Skin Cancer). They hypothesised that people whose dietary fat intake is low will be more susceptible to skin cancer. The study compared...