Question

2. Two simple and inexpensive screening methods have been developed to identify individuals with HIV infection at routine medical check-ups. To study the sensitivity and specificity, both methods were tested on 12860 persons who underwent a simultaneous and thorough clinical examination that was considered to give an accurate diagnosis. There were 1900 cases of disease as diagnosed by clinical methods. The Screening test #1 was positive for a total of 1000 people, including 800 with active HIV infection. The screening method #2 was positive for 2444 individuals. This method also detected 800 individuals diagnosed with active HIV as positive.

a) Calculate the sensitivity of each screening method.

b) Calculate the specificity of each screening method.

C) What is the positive predictive value of each screening method?

d) What is the negative predictive value of each screening method?

3. With respect to the above question, which screening method would you recommend be used in routine medical checkup. Give your reason for this recommendation.

Answer 1