Specific mortality rates may be calculated for population subgroups defined by age, sex, race, or other demographic factors.
Combinations of factors are often used.
For example, the mortality rate attributed to HIV among 25-to-44-year-olds in the US in 1987 was:
This is an example of a cause- and age-specific mortality rate.
Case Fatality Rate
The case fatality rate is often used as a measure of the severity of an infectious disease. It is the proportion
of known cases who died of the disease in question. For example, in an outbreak of 20 cases of invasive meningococcal
disease on a large university campus, 3 patients died. The case fatality rate was 3/20 or 15%.