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Relative Risk and Odds Ratio
Attributable Risk
Readings from the texts
Page, et al 105-107,115-120
Problems
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worked it.
1. Knekt, et al (1996) explored the association between a
diagnosis of depression and incidence of lung and breast cancer.
They followed a population based sample of subjects for 14 years.
and obtained the following results for males. High scores
indicate more symptoms of depression.
Depression Score Number at risk Lung Cancer
1.00-1.49 930 12
1.50-2.49 2034 44
2.50-4.00 281 14
Knekt, P., Raitasalo, R., Helibvaara, M., Lehtinen, V., Pukkala,
E., Teppo, L., Maatela, J. and Aromaa, A. (1996) Elevated lung
cancer risk among persons with depressed mood. American Journal
of Epidemiology, 144:1096-1013.
a. Compute relative risks for scores of 1.50-2.49 and 2.50-4.00
compared to scores of 1.00-1.49.
b. Put 95% confidence bounds around these estimates.
c. What do you conclude about the association between depression
and development of lung cancer?
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2. Page, et al (1985) studied over ten thousand breast biopsies.
They followed the women for an average of 17.5 years. Of the 150
women who had atypical ductal hyperplasia (ADH) 18 developed
cancer. The relative risk for these women as compared to women
without proliferating disease (WP) was 4.3.
Page, D., Dupont, W., Rogers, L. and Rados, M. (1985) Atypical
hyperplastic lesions of the female breast A long-term follow-up
study. Cancer 55:2698-2708.
a. What is the probability that a woman with ADH develops
cancer?
b. What is the probability that a woman with WP develops cancer?
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3. Page, et al (1985) also report the following data.
Group Total Women Cancer
All women with ADH 150 18
No family history 122 11
Family history 28 7
a. What is the relative risk for family history vs no family
history among these women?
b. Put a 95% confidence interval around this risk.
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4. In session two we reported data relating oyster consumption
to having hepatitis A. The data is repeated below.
Ate Oysters
No Yes Total
Case 2 51 53
Control 31 33 64
Total 33 84 117
a. Compute an odds ratio showing the risk of eating oysters in
the development of disease.
b. Put a 95% confidence interval around the odds ratio.
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5. Find the estimate of the etiologic fraction for lung cancer
due to symptoms of depression using the data
given in problem one. Ignore the middle category of
depression.
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