Question

Suppose that you began a one-year study of tuberculosis (TB) on January 1st, 2013. You enrolled 500 residents in your study and checked on their TB status on a monthly basis. At the start of your study on January 1st, you screened all 500 residents. 30 residents already had existing cases of TB on January 1st. On February 1st, 5 residents developed TB. On April 1st, 5 more residents developed TB. On July 1st, 10 of the residents who had existing TB on January 1st died from their disease. The study ended on December 31, 2010. Assume that once a person gets TB, they have it for the duration of the study, and assume that all remaining residents stayed healthy and were not lost to follow-up. What was the case-fatality rate among residents with TB over the course of the year? a. 0% b. 25% c. 50% d. 100%

Answer 1

Case fatality rate is the proportion of people who die from a specified disease among all individuals diagnosed with the disease over a certain period of time.

Here number of residents who had TB is 30+5+5=40

And number of residents who had TB and died is 10

Hence by definition the rate is

${10\over 40}\times 100=25\%$

Option B) is correct