Select false statement regarding case fatality rate
**Core Concept**
The case fatality rate (CFR) is a measure of the severity of a disease, defined as the proportion of individuals with a specific disease who die from that disease. It is a critical public health metric used to assess the impact of a disease outbreak or epidemic.
**Why the Correct Answer is Right**
The correct answer is the statement that does not accurately describe the case fatality rate. CFR is a ratio of the number of deaths due to a disease, divided by the number of individuals diagnosed with the disease, usually expressed as a percentage. This measure is often used to compare the severity of different diseases or to evaluate the effectiveness of treatment strategies.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because CFR is indeed a measure of disease severity, and it is calculated by dividing the number of deaths by the number of cases. This option is a true statement about CFR.
**Option B:** This option is incorrect because CFR is a measure of disease severity, not disease incidence. Disease incidence refers to the number of new cases of a disease occurring within a population over a specified period.
**Option C:** This option is incorrect because CFR is a ratio, not a rate. Rates are typically expressed as events per unit of time (e.g., cases per 100,000 population per year), whereas ratios are simply a comparison of two numbers (e.g., deaths per case).
**Option D:** This option is incorrect because CFR is indeed a proportion, but it is a proportion of deaths to cases, not a proportion of cases to deaths.
**Clinical Pearl / High-Yield Fact**
To remember the difference between incidence and prevalence, use the following mnemonic: "Incidence is new, prevalence is old." Incidence refers to the occurrence of new cases of a disease, whereas prevalence refers to the total number of cases of a disease, including both new and existing cases.
**Correct Answer:** D. CFR is a proportion of deaths to cases, not a proportion of cases to deaths.