The nurse is conducting research on the relative risk of acquiring lung cancer as a result of being exposed to secondhand smoke. The nurse is studying two different groups

Question

Group A includes 400 adults who do not smoke but are exposed to secondhand smoke in their home on a daily basis. Group B includes 400 adults who do not smoke and are not exposed to secondhand smoke in their home. Over the course of 10 years, 20 subjects in Group A are diagnosed with lung cancer, whereas only 2 subjects in Group B are diagnosed with lung cancer. Which is the relative risk ratio that would result from this study?
A) 0.5
B) 1
C) 5
D) 10

Answer 1

Ans: D
Feedback:
Relative risk ratio compares the incidence rate of a group exposed to a certain risk factor with the incidence rate of a group not exposed to the risk factor. It is calculated by dividing the incidence rate in the exposed group by the incidence rate in the nonexposed group. In this case, we need to first calculate the separate incidence rates for Group A and Group B and then divide to find the relative risk ratio. The incidence rate for Group A is calculated as follows: 20/400 = 0.05 × 1,000 = 50 cases per 1,000 population. The incidence rate for Group B is calculated as follows: 2/400 = 0.005 × 1,000 = 5 cases per 1,000 population. The relative risk ratio, then, is calculated as follows: 50/5 = 10.