Question

A five-year prospective cohort study has just been completed. The study was designed to assess the association between supplemental vitamin A exposure and mortality and morbidity for measles. The relative risk for incidence of measles was 0.75 and the relative risk for measles mortality was 0.5. Regarding the relative risk, which statement is correct?

a. Exposure to vitamin A appears to protect against morbidity and mortality for measles.
b. Exposure to vitamin A appears to be a risk factor for morbidity and mortality for measles.
c. Exposure to vitamin A is not associated with morbidity and mortality for measles.
d. Exposure to vitamin A is a risk factor for morbidity and a protective factor for mortality for measles.

Answer 1

Assessing the association between supplemental vitamin A exposure and mortality and morbidity for measles:

Regarding the relative risk, the correct statement is:

a. Exposure to vitamin A appears to protect against morbidity and mortality for measles.

Explanation:

Relative risk for incidence of measles = 0.75

Relative risk for measles mortality = 0.5

Relative risk for mortality and morbidity for measles = 0.375 (0.75 * 0.5)

The combined relative risk is less than 50%

The association is weak because RR is less than 1.

Therefore, there is no association between supplemental vitamin A exposure and mortality and morbidity for measles.