ELISA for HIV testing (Biostats Q)

[acciddropping]

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hey guys,
Can you please explain why In HIV testing, ELISA screening is sensitive (which I understand) and has a high FP rate (why? how?) with a low threshold (how?)?

My thinking is that since ELISA is a screening test as supposed to Western which is a confirming test, ELISA has a higher SN (that means it has higher TP and lower FN) ==> that's where the confusion comes where they talk about FP which I thought had to do with the SP test. Hope you can clarify this concept. Thanks.

 

[HatWobble]

ELISA is A. Western Blot is B.

 

[dyspareunia]

hey guys,
Can you please explain why In HIV testing, ELISA screening is sensitive (which I understand) and has a high FP rate (why? how?) with a low threshold (how?)?

My thinking is that since ELISA is a screening test as supposed to Western which is a confirming test, ELISA has a higher SN (that means it has higher TP and lower FN) ==> that's where the confusion comes where they talk about FP which I thought had to do with the SP test. Hope you can clarify this concept. Thanks.

ELISA is not as specific as Western blot. Higher sensitivity only means low false negative.

In other words, if you have a negative result from a highly sensitive test, then you likely don't have the disease. However, a positive result from a high sensitivity test (ELISA) must be confirmed by a high specificity test (western blot).