Enter only numbers into your answer. Round to two decimal places after completin
ID: 78873 • Letter: E
Question
Enter only numbers into your answer. Round to two decimal places after completing mathematical operations. Express your answer as a percent with two decimal places, but do NOT place a % sign after your answer.
St. Broncoville Regional Medical Center is evaluating whether to replace annual the current HIV blood test which is sent out to the reference laboratory with a new HIV rapid test which can be done in house. Approximately 5.5% of the 40,000 Broncoville population is HIV positive. The new HIV rapid test is 98% sensitive and 96% specific. Develop a 2 x 2 table.
1. Calculate the Positive Predictive Value (PPV) for the new rapid HIV test.
2. Calculate the Negative Predictive Value (NPV) for the new rapid HIV test.
Explanation / Answer
Answer:
Condition(HIV)-->
Test
Condition positive
Condition negative
Total
Test Positive
TP- 220
FP-1658
1878
Test Negative
FN-4
TN- 39780
39784
Total
224
39780
True positive(TP) as per the data 5.5% of 40000= 220
Rest will be true negative=40000-220=39780
Sensitivity-TP/TP+FN=98
So TP+FN=220*100/98=224
So FN=224-220=4
Specificity= TN/FP+TN=96
So FP+TN=39780*100/96=41438
So FP=41438-39780=1658
Positive predictive value for new rapid HIV test
= TP / (TP + FP)
= 220/1878*100= 11.71
Negative predictive value for new rapid HIV test
= TN / (FN + TN)
= 39780/ 39784*100 99.98
Condition(HIV)-->
Test
Condition positive
Condition negative
Total
Test Positive
TP- 220
FP-1658
1878
Test Negative
FN-4
TN- 39780
39784
Total
224
39780
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