Question

Question:
20% of participants have a disease. The exposed group has a 95% higher risk of this disease compared to the group that with no exposure. What is the relative risk?

Answer 1

Relative risk is given by

RR = a/(a+b) / c/(c+d)

where , a b , c,d are given by

	cases	control
exposed	a	b
control	c	d

Let there be 100 participants (50 exposed , 50 unexposed)

Out of which 20 have the disease (20%)

Let X be the number of people in the exposed group who have the disease

then 20-X is the number of people in the control group who have the disease

According to given information

number of people in the exposed group who have the disease =19.5

number of people in the control group who have the disease = 0.5

The contingency table

	cases	control
exposed	19.5	30.5	50
control	0.5	49.5	50
	20	80	100

Thus , relative risk

RR= (19.5/50) / (0.5/50) = 39

Exposed group has 39 times greater risk than control group

relative risk =39  

X-(20-x) /20 =0.95

2x-20 = 19

x=19.5