City A has a population of people who are exposed to HIV, whereas ...

[Mollykgkg]

City A has a population of people who are exposed to HIV, whereas City B has a population of people who are considered nonexposed to HIV. There were 3,267 new HIV cases in a given year for City A, with a population (exposed) of 10,000,000.
 
  There were only 5 new HIV cases in the same year for City B, with a population (nonexposed) of 150,000. Which is the attributable risk of HIV occurring in City A in terms of cases per 100,000 population?
  A) 3.33
  B) 13.55
  C) 29.34
  D) 32.67

Question 2

In reviewing a study that considered the sensitivity of a particular screening test for HIV, the nurse found 21 true positives, 853 true negatives, 3 false positives, and 5 false negatives. What is the sensitivity of this test?
 
  A) 80.8
  B) 87.5
  C) 93.7
  D) 99.6

[courtney_bruh]

Answer to Question 1

Ans: C
Feedback:
Attributable risk is calculated by subtracting the incidence rate in a nonexposed population from the incidence rate in an exposed population. In this case, we first need to calculate the individual incidence rates for City A and City B and then subtract to find the attributable risk for City A. The incidence rate for City A is calculated as follows: 3,267/10,000,000 = 0.0003267  100,000 = 32.67 cases per 100,000 population. The incidence rate for City B is calculated as follows: 5/150,000 = 0.0000333  100,000 = 3.33 cases per 100,000 population. The attributable risk for HIV occurring in City A, then, is calculated as follows: 32.67  3.33 = 29.34 cases per 100,000 population.

Answer to Question 2

Ans: A
Feedback:
Sensitivity is calculated by dividing the number of true positives by the sum of the number of true positives and false negatives. In this case, the sensitivity would be calculated as follows: 21/21 + 5 = 21/26 = 0.808 = 80.8.

[Mollykgkg]

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