Question

Study 4

In a study of people with Hypertension, 65,000 people with hypertension were followed for 5 years. All were screened negative for Parkinson’s diseases (PD) when they entered the study. To control their hypertension the population was taking either calcium channel blockers (CCBs), angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs). 25,000 people were taking CCBs, 20,000 were taking ACEIs and 20,000 were taking ARBs. This study wanted to look at the exposure to CCBs and ARBs and if it led to PD. The incidence of PD in those taking CCBs was 27/1000 and the incidence for those taking ARBs was 22/1,000.

Label the table and fill it in.

1. What type of study is this?

a. cross-sectional

b. case report/series

c. ecologic

d. case-control

e. cohort

f. clinical trial

g. community intervention

2. What is the most appropriate measure of association?

a. odd ratio

b. relative risk

c. Attributable risk

d. none of these

3. Calculate the measure of association (use two decimal places).

4. How would you best describe the relationship between the exposure and the outcome?

a. no relationship

b. positive relationship

c. negative relationship

5. If appropriate, calculate the attributable risk per 1000 people (use 2 decimal places).

***would you mind showing all of your work? Thank you!

Answer 1

Sol:

1).

This is a type of prospective Cohort study. Since, a specific group of individual with the same characteristics are taken, it is known as a cohort and they are divided into groups, based upon the drug treatment they are given and outcomes and risk for Parkinson's Disease compared.

2).

Relative Risk is the most appropriate indicator of association in this type of study. It assess the risk of development of a disease in particular situation with another.

3).

Incidence of PD in group taking CCB's= 27/1000. Total Number of people taking CCBs is 25000. And hence total number of people who developed PD with CCBs was 27*25000/1000= 675 individuals.

Incidence of PD in group taking ARBs= 22/1000. Total number of people taking ARBs is 20000. And hence total number of people who developed PD WITH ARBs was 22*20000/1000= 440 individuals.

Risk percentage of PD with CCBs= 675*100/25000= 2.7%

Risk percentage of PD with ARBs = 440*100/20000

Risk percentage of PD with ARBs = 2.2%

Relative risk of PD with CCB and ARB = 1115*100/45000

Relative risk of PD with CCB and ARB = 2.47%

Relative Risk with CCBs = 2.7/2.47

Relative Risk with CCBs = 1.09

Relative Risk with ARBs= 2.2/2.47

Relative Risk with ARBs = 0.89

4).

. Relative Risk is more than 1 for CCBs i.e. CCBs can be a causative factor for development of PD in HTN.

Relative Risk is less than 1 for ARBs i.e. ARBs can be considered as a protective factor for development of PD in HTN.

5).

Attributable Risk cannot be calculated because the cohort has been divided into two separate groups and attributable risk as a whole cannot be evaluated. Calculating attributable risk of individual exposure will give false result. It is already mentioned, if appropriate.

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