Which one of the following is a good index of the severity of an acute disease ?
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
Cause specific death rate
Case fatality rate
Standardized mortality ratio
Five year survival