Question

You are testing the effect of a new drug to treat severe viral pneumonia. To do this you conduct a randomized controlled trial. You enroll 200 participants in your study; 100 are allocated to the intervention arm (they receive the drug) and 100 receive the current standard of care. 7 of the participants in the intervention arm and 15 of the participants in the standard care arm die of pneumonia.

a)Calculate the RR of survival. Round to the nearest hundredth.

b)Calculate the OR of death. Round to the nearest hundredth.

c)Calculate the OR of survival. Round to the nearest hundredth.

Answer 1

Solution:

From given information, we have following data:

	Died	Survived	Total
Intervention	a = 7	b = 93	a+b = 100
Standard	c = 15	d = 85	c + d = 100
Total	a+c = 22	b+d = 178	200

a) Calculate the RR of survival. Round to the nearest hundredth.

RR of survival = Risk of survival for intervention / Risk of survival for standard care

RR of survival = (93/100)/(85/100) = 0.93/0.85 = 1.094118

(Use formula, RR = (b/(a+b))/(d/(c+d)), formulas are constructed according to above table. Formula may be change if we change the order of letter a,b,c,d.)

RR of survival = 1.09

b) Calculate the OR of death. Round to the nearest hundredth.

OR of death = (a/b)/(c/d) = (7/93)/(15/85) = 0.075269/ 0.176471 = 0.426523

OR of death = 0.43

c) Calculate the OR of survival. Round to the nearest hundredth.

OR of survival = (b/a)/(d/c) = (93/7)/(85/15) = 13.28571/ 5.666667 = 2.344538

OR of survival = 2.34