Question

A study was conducted to determine association between physical fitness and overall mortality among adults between 40 and 70 years of age. Researchers identified 500 study participants who exercised 3 or more times per week (exposed) and 500 study participants who exercised less than 3 times per week (unexposed). The study participants were followed over time until they died, were lost to follow-up, or up to a maximum 10 years of follow-up. The high exercise group had 26 deaths and accumulated 3,876 person years of follow up. The low exercise group had 41 deaths and accumulated 2,997 person years of follow up.

Create the appropriate 2 x 2 table for the data. Include appropriate row and column labels and complete the table with information provided in the scenario.

Calculate the mortality rates for the high exercise group (1 point) and the low exercise group (1 point). Express per 1,000 person-years?

Calculate the rate ratio for the relationship between high exercise and mortality?

Answer 1

	DEATHS	NO DEATH	TOTAL
EXPOSED	26	474	500
NON EXPOSED	41	459	500

EXPOSED = individuals exercising 3 or more times a week

NON EXPOSED= individuals exercising less then 3 times a week

This is the 2X2 table for the data given.

Answer 2

Mortality rate for high exercise group =
Mortality in high exercise group

Person year follow up

= 26

3876
=  0.0067 person year

= 0.0067 X 1000

= 6.70 per 1000 person year (Answer)

Mortality rate for low exercise group -

=Moratlity in low exercise group X 1000

Person year follow up

= 41
2997

= 0.0136 Person year

= 0.0136 X 1000

= 13.6 per 1000 Person year ( Answer)

Answer 3

Rate Ratio = Incidence in exposed

Incidence in non exposed

​​​​​​​ Incidence in exposed = 26/ 500

Incidence in non exposed = 41/ 500​​​​​​​

​​​​​​​SO, Rate Ratio = 26/500

   41/500

= 0.634

Answer- Rate ratio is 0.634

NOTE:

If

Rate ratio = 1 then Incidence in exposed and unexposed is same and exposure is not associated with disease.

Rate ratio < 1 then Incidence in exposed is lower then unexposed and exposure is negatively associated with disease.

Rate ratio > 1 then Incidence in exposed is higher then unexposed and exposure is positively  associated with disease.