testing (SENSITIVITY VERSUS SPECIFICITY)
Feb 9, 2008
On previous posts you say that the western blot test is more sensetive and other informaton that I have read says it is the more specific test. What is the difference between the western blot and the elisa test? Thank You
Response from Dr. Frascino
You are correct. I was using the word sensitive in its generic sense. That is trying to reassure the questioner that the Western Blot was the test to rely on to confirm a positive ELISA or determine the ELISA was falsely reactive.
The technical terms sensitivity and specificity are defined below:
The specificity is the number of true negatives (disease-free) divided by the number of all negative cases in the population.
The sensitivity is the number of true positives (with disease) divided by the number of all positive cases in the population.
Consequently, using the technical definitions, what you read is correct. Western Blot (WB) tests would be more "specific." They would be able to determine "true negatives" better than an ELISA, which is more sensitive (i.e. able to determine more true positives than the WB).
Hope that helps. I know it's a bit confusing.
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