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June 28th, 2014

CDC Nixes HIV Western Blot in Latest Testing Guidelines

Finally, it’s official — the Western blot is no longer recommended as a confirmatory test for HIV infection. From the latest Laboratory Testing for the Diagnosis of HIV Infection, updated June 27:

The HIV-1 Western blot and HIV-1 immunofluorescence assay, previously recommended to make a laboratory diagnosis of HIV-1 infection, are no longer part of the recommended algorithm.

It’s been clear now for years that the Western blot’s sensitivity for early HIV infection was markedly inferior to the latest generations of HIV screening tests; this difference became even starker with the approval of the combined “fourth generation” antigen/antibody tests.

This put clinicians in the bizarre situation of having to ignore, or disregard, the test that’s supposed to be more accurate than the screening test. Essentially every patient with a positive ELISA and negative Western blot would need a follow-up HIV RNA test of some sort to exclude early HIV. Read here for more information.

I’ve pasted the new recommended algorithm below. Let’s hope that labs that still use the old “reactive ELISA –> Western blot confirmation” practice quickly move to this new approach. And kudos again to HIV Testing Guru (yes, that’s his official title) Bernie Branson for getting this important change into the guidelines.

HIV Testing Algorithm 2014 jpg

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HIV Information: Author Paul Sax, M.D.

Paul E. Sax, MD

Contributing Editor

NEJM Journal Watch
Infectious Diseases

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