In public health, how do prognosis and case fatality rate differ?

• A. Prognosis is the probability of recovery; case fatality rate is the rate of new cases.
• B. Prognosis is the expected outcome for an individual; case fatality rate is the proportion of cases that die.
• C. Prognosis measures resource use; case fatality rate measures infection rate.
• D. Prognosis and case fatality rate are interchangeable.

Answer: (B)

The central idea here is distinguishing an individual’s expected disease outcome from a population-level measure of disease severity. Prognosis refers to what can be expected for a specific patient with a disease—their likely course, including chances of recovery, progression, complications, or death over a defined time, and it often uses factors like age, stage, comorbidities, and treatment. Case fatality rate, by contrast, is a descriptive statistic about a group: the proportion of people diagnosed with the disease who die from it within a certain period. It describes how deadly the disease appears in that population, not what will happen to a particular person. So prognosis is about an individual’s likely outcome; case fatality rate is about the share of cases that result in death across a group. This isn’t a rate of new cases (that would be incidence), and they aren’t interchangeable—one informs personal clinical expectations, the other informs public-health understanding of disease severity in a population.