Question

Results of a study comparing cancer mortality in Boston, MA, and Miami, FL were published in a national newspaper.

• In Boston, the crude death rate from cancer was 150 / 10,000 persons per year and the age-adjusted death rate from cancer was 175 / 10,000 person per year.
• In Miami, the crude death rate from cancer was 220 / 10,000 persons per year and the age-adjusted death rate from cancer was 108 / 10,000 person per year.

A. Is age-standardization needed to make a fair comparison? YES OR NO? (0.5 Point)

B. Why or why not in ONE SENTENCE (1 point)

Answer 1

A. Yes, age-standardization is needed to make a fair comparison.

B. To avoid misleading comparison as the death rate can depend hugely on the confounding factors like age.

Elaborated Reason: When comparing two or more populations with respect to a health outcome, it is tempting to compare crude rates of disease, i.e., the number of disease events divided by the size of the population. However, comparisons of crude rates can be misleading because of confounding if the populations being compared have different distributions of other determinants of disease, such as age which has an important effect on many health outcomes, such as mortality, heart disease, cancer, etc. As a result, differences in age can distort other comparisons between populations, and this distortion is called confounding. This gives birth to standardization that allows one to compute summary rates of health outcomes that are adjusted to take into account differences in confounding factors like age in order to provide a less distorted comparison.

Direct standardization applies a standard age distribution to the populations being compared in order to compute summary rates indicating how overall rates would have compared if the populations had had the same age distribution.