The Nurses’ Health Study, a cohort study investigating the relationship between
ID: 3203440 • Letter: T
Question
The Nurses’ Health Study, a cohort study investigating the relationship between hypertension and the subsequent incidence of heart attacks among women, found that of the 13,422 women with hypertension 117 had a heart attack. They also found that out of the 106,541 women without hypertension, 106,416 did not have a heart attack.
Organize the data in a table that will be used to determine relative risk (also called risk ratio) for a heart attack. Label the table columns and rows. The shaded area represents the main portion of the 2 X 2 table.
Exposure:
Outcome:
Total
Yes
No
Yes
117
13,305
13,422
No
125
106,416
106,541
Total
242
119,721
119,963
A.Calculate the relative risk (RR) for a heart attack among those with hypertension as compared to those without hypertension.
B.Explain your answer to (B) above in narrative form.
C.Compute the risk difference for women with hypertension. Then, express your answer per 100,000.
D.Explain your answer to (D) above in narrative form. Do not simply give the definition of risk difference, rather explain the interpretation of risk difference in the context of this specific problem.
E.Calculate the attributable proportion among total population (APt).
F.Explain your answer to (F) above in narrative form.
Exposure:
Outcome:
Total
Yes
No
Yes
117
13,305
13,422
No
125
106,416
106,541
Total
242
119,721
119,963
Explanation / Answer
A.) Relative risk=RR
= (risk of heart attack for women with hypertension)/(risk of heart attack for women without hypertension)
risk of heart attack for women with hypertension = 117/13442 = 0.0087
risk of heart attack for women without hypertension = 125/106541 = 0.00117
So RR = 7.4359
B) The above calculation shows that women with hypertension are about 7.44 time more likely to get a heart attack compared to those without hypertension.
C) Risk Difference
=risk of heart attack for women without hypertension - risk of heart attack for women without hypertension
= 0.00753
D) The calculation of the risk difference shows that on an average women with hypertension have a higher risk of getting a heart attack than those without hypertension. The risk of getting a heart attack increases by 0.753 % with hypertension.
E) Attributable proportion =
(Risk Difference)/(risk of heart attack for women with hypertension) = 0.8655
F) The above mean that 86.55% of the risk of getting a heart attack for a woman with hypertension can be attributed to their having hypertension.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.