Question

Researchers are interested in the effectiveness of a new anti-retroviral medication at increasing 5 year survival for HIV infected persons with Hepatitis C. In order to test the efficacy of the new study drug, the researchers randomly assigned participants to receive either the new medication or a placebo. The following table summarizes preliminary results of the trial.

Deceased Non-Deceased Total

New Vaccine 55 84 139

Placebo 61     67 128

Total 116 151 267

A) Calculate the relative risk for mortality among those treated with the new vaccine versus the placebo.

B) Interpret the relative risk measurement.

1.

A) RR=0.33 B) Those that are provided the new vaccine are at a 0.33 times decreased risk for 5 year mortality compared to those receiving the placebo.

2.

A) RR=0.83 B) Those that are provided the new vaccine are at a 0.83 times decreased risk for 5 year mortality compared to those receiving the placebo.

3.

A) RR=0.65 B) Those that are provided the new vaccine are at a 0.65 times decreased risk for 5 year mortality compared to those receiving the placebo.

Answer 1

relative risk for mortality =(55/139)/(61/128)= 0.83

Correct option is:

2) A) RR=0.83 B) Those that are provided the new vaccine are at a 0.83 times decreased risk for 5 year mortality compared to those receiving the placebo.