Question

4) Dr. Jackson took a trip to a remote island that has 750 residents because she was interested in studying kidney disease within the population. She took a blood tests on all residents to determine if they had kidney disease. If 50 of the residents tested positive for kidney disease, what would be the prevalence of kidney disease?

Answer:  Prevalence of kidney disease = Number of residents tested positive / Total number of residents

= 50 / 750

= 0.067

Extra credit - Use the information from question 4 to answer the following question:

Dr. Jackson wanted to estimate the incidence of kidney disease in the population over the next 12 months (after her first round of test). She did another blood test and found that 25 people had kidney disease. What is the incidence

Answer 1

The incidence rate is basically the amount of newly reported cases with a given timeframe. Here on the above example, 50 out of 750 size population already developed the kidney disease at the beginning of the test, so we can exclude this number and concentrate only on (750-50)= 700 size population.

Now out of this 700, at the end of 12 months, 25 more was found to be infected with kidney diseases. So we can conclude that 25/700= 0.0357 or 3.57 per hundred over a period of 12-month is the incidence rate.