1. A cohort study is conducted to assess the associa- tion between clinical char
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Question
1. A cohort study is conducted to assess the associa- tion between clinical characteristics and the risk of stroke. The study involves n = 1250 participants who are free of stroke at the study start. Each participant is assessed at study start (baseline) and every year thereafter for 5 years. Table 3-8 displays data orn ypertension status measured at baseline and hyper- tobe identical or cumulative erson-time data pring. Censoring ase status) is not time constraints bjects are lost to ady). In epidemi- of censoring that tension status measured 2 years later. a. Compute the prevalence of hypertension at baseline. b. Compute the prevalence of hypertension at 2 years c. Compute the cumulative incidence of hyperten sion over 2 years. TABLE 3-8 Hypertension at Baseline and Two Years later Two Years Later: Not Hypertensive Two Years Later: Hypertensive Baseline: Not hypertensive 850 148 Baseline: hypertensive 45 207Explanation / Answer
Solution:-
a) The proportion of participants has optimal blood pressure is 0.16667.
Total participants = 390
Number of participant who have optimal blood pressure = 65
The proportion of participants has optimal blood pressure = 65/390 = 0.16667
b) The proportion of men has optimal blood pressure is 0.14667.
Total number of mens = 150
Number of participant who have optimal blood pressure and mens = 22
The proportion of men has optimal blood pressure = 22/150 = 0.14667
c) The proportion of participants with hypertension is men is 0.4583.
Total number of participant who have hypertension = 120
Number of participant who have hypertension and men = 55
The proportion of participants with hypertension is men = 55/120 = 0.4583
d) No, hypertensive status and male gender are not independent.
To prove that two variables (Hypertension and Male gender) are independent, we must show that
P( H and M) = P(H | M) * P(M) = P(H) * P(M)
55/390 = 55/150*150/ 390 = 120/390 *150/390
0.14103 = 0.14103 = 0.1183
Hence not independent.
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