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]

(b) What was the data source used to identify first event of Coronary Heart Disease? [2 marks]

(c) Why the authors excluded 1894 participants who rated their general health as “poor” ? [2 marks]

(d) What was the crude overall incidence of CHD ? [2 marks]

(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]

(f) How would you interpret the relative risk in the above question (e)? [3 marks]

(g) Is the relative risk for this study better described as a risk ratio or a rate ratio? Why? [2 marks]

(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]

(i) Why do you think the author could not adjust for these confounders? Hint: think about the way this study was designed [4 marks]