ERHS 332 Colorado State University Controlled Clinical Trials & A cross-sectional Case Study

Assignment 4

Assignment Directions: Submit assignment in Canvas (leaving format open intentionally) by March 26 at 9:30am. Make sure your name is on the first page (above) and in the document file name (first.last.extension) (you will lose 2 points if these directions are not followed). Show all work for full credit. Short answers need to be typed; calculations may be hand-written. If the assignment is turned in late, you will lose 10 points for every 24 hours after the due date and time. The assignment is in a Word document so that you may type within the document. Show your work.

For questions 1-6, name the type of study design and list the pros and cons for that study type:

1.Epidemiologists want to evaluate the effect of screening on colon cancer in the United States. They ascertain the mortality rates from colon cancer in each of the 50 U.S. states as well as the average (mean) number of residents in each state undergoing colonoscopy screening.

Study Design:

What is the primary limitation of this study design?

2.A group of doctors is concerned that breast feeding might lead to an increased risk of developing breast cancer. To examine this possible association, they hire a team of epidemiologists to evaluate the relationship between breast cancer and a woman’s history of breastfeeding. The epidemiologists select women with breast cancer and an age-matched sample of women without breast cancer who live in the same neighborhoods. Study subjects are interviewed to determine breast feeding history of each participant.

Study Design:

Name one strength and one limitation of using this study design.

Strength:

Limitation:

3.Researchers wanted to investigate ergonomic hazards for workers, specifically back pain. They recruited current workers from the Automobile Manufacturing Union. Workers were asked about chronic (prevalent) back pain symptoms, their job duties, and demographics (e.g., age, race, etc.).

Study Design:

Name one strength and one limitation of using this study design.

Strength:

Limitation:

4.Scientists wanted to evaluate innovative breast cancer treatments involving cryotherapy. They designed a study that compared two treatments of breast cancer. Women with stage 1 breast cancer were randomized to receive either cryotherapy (the new treatment) or the traditional lumpectomy. The women were then followed for 5 years to determine whether there were any differences in breast cancer recurrence and survival between the two treatments.

Study Design:

Describe the primary strength of this study design:

5.A researcher wanted to investigate the effects of early drinking (alcoholic beverages) on academic development and performance. They enrolled participants from 10 different schools in two neighboring states and obtained self-reported data on alcohol intake and school performance from students beginning in grade seven, and then again in grades 10 and 12 and then at age 23 for an overall follow-up period of 10 years.

Study Design:

Name one strength of this study design:

6.A team of epidemiologists began a study in 2010 to investigate the relationship between exposure to chest irradiation and the subsequent risk of breast cancer. Women who received therapy (either radiation or non-radiation) for postpartum mastitis in the 1950s, and who were free of breast cancer at the time, were enrolled in the study. The women were followed for 60 years to determine the incidence rates of breast cancer in each group.

Study Design:

Name one strength and one limitation of using this study design.

Strength:

Limitation:

7.A common problem with HIV is that mothers infected with HIV can pass the virus on to their infant at birth. A group of scientists conducted a study to evaluate the effectiveness of a drug (Zidovudine) in reducing maternal-infant transmission of HIV. They enrolled 363 pregnant women with HIV; 180 of these women received the Zidovudine treatment. A total of 53 infants tested HIV positive; 40 of the 53 infants who tested positive received the placebo instead of the treatment. Create and fill in a 2×2 table (OPTIONAL) to help you answer the following questions:

a.What is the cumulative incidence of HIV in infants who received the treatment (exposed)?

b.What is the cumulative incidence of HIV in infants who received the placebo (not exposed)?

c.What can you conclude from this?