Health Medical Homework Help

Question 2

Researchers conducted a prospective cohort study to investigate whether the use of oral contraceptives increases a woman’s risk of stroke. 3500 women between the ages of 18 and 35 with no history of stroke were asked about their oral contraceptive (OC) use in January 2016. 1180 women reported current OC use and 2320 did not. At the end of the 3-year follow-up period, 130 of the OC users and 195 of the OC non-users had suffered from a stroke.

1. Based on the information provided above, please fill-in the 2×2 table below.

	Stroke	No Stroke	Total
OC use
No OC use
Total

1. What was the cumulative incidence of stroke over the 3-year period for the entire cohort? Show all of your work and round your final answer to 2 decimal points.

1. What was the cumulative incidence (risk) of stroke over the 3-year period among OC users? Show all of your work and round your final answer to 2 decimal points.

1. What was the cumulative incidence (risk) of stroke over the 3-year period among OC non-users? Show all of your work and round your final answer to 2 decimal points.

1. Calculate the risk ratio for stroke comparing OC users to OC non-users. Show all your work and round your final answer to 2 decimal points.

1. Interpret the risk ratio calculated in (e) above.

1. Based on the risk ratio you calculated in (e) above, is OC use potentially harmful or potentially protective? Please explain your answer.

1. Suppose some women were lost to follow-up during the 3-year study period. Calculate the incidence rate for stroke among OC users and OC non-users assuming OC users were observed and at risk for 21,311 person-months and OC non-users were observed and at risk for 52,702 person-months. Show all your work for each calculation. Express your final answers per 1,000 person-months and round your final answers to 1 decimal points.

1. Calculate the rate ratio for stroke comparing OC users to OC non-users. Show all your work and round your final answer to 2 decimal points.

1. Interpret the rate ratio calculated in (i) above.

Question 3

BACKGROUND

It has been suggested that vaccination against measles, mumps, and rubella (MMR) is a cause of autism.

METHODS

In 2005, we conducted a cohort study of all children born in Denmark from January 1991 through December 1998. The cohort was selected on the basis of data from the Danish Civil Registration System, which assigns a unique identification number to every live-born infant and new resident in Denmark. MMR-vaccination status was obtained from the Danish National Board of Health. Information on these same children’s autism status was obtained from the Danish Psychiatric Central Register, which contains information on all diagnoses received by patients in psychiatric hospitals and outpatient clinics in Denmark. We obtained information on potential confounders from the Danish Medical Birth Registry, the National Hospital Registry, and Statistics Denmark.

RESULTS

Of the 537,303 children in the cohort (representing 2,129,864 person-years), 440,655 (82.0 percent) had received the MMR vaccine. We identified 316 children with a diagnosis of autistic disorder and 422 with a diagnosis of other autistic-spectrum disorders. After adjustment for potential confounders, the relative risk of autistic disorder in the group of vaccinated children, as compared with the unvaccinated group, was 0.92, and the relative risk of another autistic-spectrum disorder was 0.83.

1. What kind of cohort study is this, prospective or retrospective?

1. What are two benefits of this type of cohort study versus the other? (Would give full credit if answers make sense. They don’t need to be specifically these two.)

1. Were children already classified as developing the outcome (Autism) prior to investigators starting this study?

1. Were children already exposed (vaccinated) prior to investigators starting this study?

1. Do the study results provide evidence that vaccination was a risk factor for autism?

Question 4

The table shows whether a person survived a snakebite or not depending on whether they were administered antivenom.

	Death from a snakebite	Survived a snakebite	Total
No Antivenom (exposed)	132	140	272
Antivenom administered (unexposed)	80	340	420

1. Calculate the incidence of death attributable to not having antivenom. Round answer to three decimal places.

Formula: (Incidence in those without antivenom) – (incidence in those with antivenom)

1. In every 1000 snake bites, how many deaths are prevented by administering Antivenom?

1. Calculate the percent of incidence of death attributable to not having antivenom (attributable risk percent)

1. Explain what the answer calculated for 4C means. (2 sentences of less)

answer the following questions in the attached document

Question 1

Please indicate within in the table below whether the statements are true or false.

	Answers:
A. Cumulative incidence cannot be estimated from a retrospective cohort study
B. Prospective cohort studies are good for studying rare diseases
C. Multiple diseases can be studied in a cohort study.
D. For studying rare exposures, it is best to select a general population cohort.
E. Temporality can be established in any type of cohort study