Question

Researchers at a cardiovascular institute are concerned about the association between exercise and hypertension among their patient population. Suppose in order to assess this relationship, the researchers conducted a cohort study where a population of 35-55 year old participants were enrolled and followed for a period of 10 years, and required to submit weekly diary submissions about their exercise routines. The researchers then conducted clinic visits where blood pressure was measured and hypertensive status was confirmed. Suppose the following table illustrates the relationship when exercise habits are categorized into the following groups.

	Hypertension	No Hypertension	Total
No Exercise	105	115	220
Exercise 1-2 x Week	101	305	406
Exercise more than 2 x per Week	13	143	156
Total	219	563	782

A) Calculate the incidence of hypertension in the participant population.

B) Calculate the relative risk for hypertension using the “No exercise” group as the reference category.

C) Carry out a formal test to determine if there is a difference in the outcome between the various exercise categories. Write out your null and alternative hypotheses and interpret your results with 95% confidence.

PLEASE CHOOSE THE MOST APPROPRIATE OPTION ( Please do not post calculations that do not match the options given, I must choose one of the options and I cannot get to the right answer, thank you.

		OPTION 1               A) incidence=28.0% B) RRi(None vs >2x/wk):5.73, RRii(None vs1-2x/wk)=1.92 C) Ho: no association between exercise group and hypertension status in the source population Ha: association exists between the variables. Xi-Square stat=74.35 2 df Pvalue ~0 Reject the Ho that there is no association between exercise group and hypertension status.
		OPTION 2 A) incidence=42.3% B) RRi(None vs >2x/wk):7.73, RRii(None vs1-2x/wk)=3.22 C) Ho: no association between exercise group and hypertension status in the source population Ha: association exists between the variables. Xi-Square stat=89.26 1 df Pvalue ~0 Reject the Ho that there is no association between exercise group and hypertension status.
		OPTION 3    A) incidence=85.0% B) RRi(None vs >2x/wk):2.56, RRii(None vs1-2x/wk)=1.23 C) Ho: There is an association between exercise group and hypertension status in the source population Ha: There is no association exists between the variables. Xi-Square stat=55.47 3 df Pvalue ~0 Accept the Ho that there is an association between exercise group and hypertension status.

Answer 1

from above incidence =219/782 =0.28 ~ 28%

RR =(105/220)/(101/406)=1.92 as well RR2 =(105/220)/(13/156) =5.73

correct option is 1:

A) incidence=28.0%

B) RRi(None vs >2x/wk):5.73, RRii(None vs1-2x/wk)=1.92

C) Ho: no association between exercise group and hypertension status in the source population

Ha: association exists between the variables.

Xi-Square stat=74.35

2 df

Pvalue ~0

Reject the Ho that there is no association between exercise group and hypertension status.