epidemiology homework

Assignment Directions: Submit assignment in Canvas by 9:30am, April 7. Show all work for full credit!

The answer key will be posted after 9:30am April 7. Late assignments will not receive points. Please plan ahead!

1.Researchers examined the association between infection with herpes virus (exposure) and the development of Alzheimer’s disease (outcome) among people aged 50 years and older in assisted living facilities in Colorado. They first identified 453 assisted living residents with a clinical diagnosis of Alzheimer’s. Next, they identified 902 residents living in the same facilities without the disease during the same time period. By extensively examining medical histories of each participant, researchers were able to determine that of the 453 Alzheimer’s patients, 167 had previously been diagnosed with herpes infection, and of the 902 without the disease, 184 had previously been diagnosed with herpes infection.

a.What type of study design is described above? [1 point]

b.Please create a 2×2 table using the information provided above. Be sure to provide labels and totals for columns and rows. [2 points]

c.Which measure of association would be appropriate for these data? Calculate this measure and present your final answer with 1 decimal place. Provide an interpretation of your calculated measure of association. [4 points]

2.Investigators were interested in examining the effects of oral contraceptive use (exposure) on breast cancer (outcome) in women. In 1976, 114,880 women without breast cancer were enrolled in a study and followed for the next 25 years. Every two years, participants were asked to complete a survey with questions about health-related topics. Contraceptive use was categorized as never (unexposed), less than 5 years, 5-9 years, and 10 or more years. Their results are summarized in the table below.

Contraception use

Breast Cancer

No Breast Cancer

10 or more years

144

3,998

5 to 9 years

327

12,748

<5 years

819

34,707

Never used (unexposed)

2,093

60,044

3,383

111,497

a.What type of study design is described above? Be specific! [2 points]

b.Which measure of association would be appropriate for these data? [1 point]

c.Please calculate the appropriate measure of association for each of the 3 exposed groups, and present your final answers with 2 decimal places (hint: you will calculate a measure of risk three times). [6 points]

d.Provide an interpretation of the measure of association when comparing 5-9 years contraception use to never used contraception. [1 point]

e.The authors are interested in determining the number of breast cancer cases that could be eliminated if women did not use oral contraceptive. What is the term for this measure? [1 point]

3.Using information provided and/or calculated in question two, provide two of Hill’s causal guidelines addressed in this study. For each guideline, provide a brief (1-2 sentences) explanation of how it was addressed. [2 points]