Which one of the following is a good index of the severity of an acute disease ?: (A) Cause specific death rate, (B) Case fatality rate, (C) Standardized mortality ratio, (D) Five year survival
Answer is B. Case fatality rate is a proportion and not a rate or ratio.

Case fatality rate (ratio)

CFR represents the killing power (severity) of a disease.

CFR = Total no. of deaths due to disease / Total no. of cases of the same disease x 100