{"id":293,"date":"2009-03-04T18:05:21","date_gmt":"2009-03-04T23:05:21","guid":{"rendered":"http:\/\/blogs.nejm.org\/?p=293"},"modified":"2015-06-04T15:31:13","modified_gmt":"2015-06-04T19:31:13","slug":"taqman-hiv-rna-assay-be-careful-what-you-wish-for","status":"publish","type":"post","link":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/taqman-hiv-rna-assay-be-careful-what-you-wish-for\/2009\/03\/04\/","title":{"rendered":"TaqMan HIV RNA Assay: Be Careful What You Wish For"},"content":{"rendered":"

\"\"<\/a>At our hospital lab, we recently switched from the bDNA viral load assay to the new Roche TaqMan real-time PCR test.\u00a0 The virologist in charge of our lab and the tech both agreed the assay was more accurate, more sensitive, and easier to do — so much so that we could increase the frequency of the test being run, a huge benefit for patient care.\u00a0 I was all for it.<\/p>\n

So what’s the problem?\u00a0 As noted here in this paper<\/a> from Vancouver — and anecdotally throughout the world\u00a0 — there’s a new epidemic of intermittent low-level viremia picked up by this assay.\u00a0 Every week, another one of my long-term successfully treated patients has a result come back at 125, 94 or — most cruelly — 49.\u00a0 (The lower limit of the assay is 48.)<\/p>\n

Plus, there’s that issue of “<48 (viral RNA detected but below the quantifiable range of the assay)” vs “Target not detected.”\u00a0 Try explaining that <\/em>to an obsessive patient who heretofore had been happily receiving “undetectable” viral load results through a decade of meticulous pill taking.<\/p>\n

One view is that these are not “false positives”, but rather represent actual detection of virus though this more sensitive assay.\u00a0 (The Vancouver group is not so sure — read the discussion section in their paper.)<\/p>\n

But if these small detections of HIV RNA are real, is there a clinical significance to it?<\/p>\n

Based on the kinds of patients in whom we are seeing these results — many on first regimens, many with no history of treatment failure — I suspect the answer will be no<\/em>.\u00a0 These low-level detectable results could be analagous to the low-level detection picked up by the single-copy assay — just a harmless release of virus from long-lived chronically productive cells, and not actual viral replication.<\/p>\n

Or to quote my esteemed colleague<\/a>:<\/p>\n

I believe we will eventually come to recognize two related but distinct situations–patients may be “fully suppressed” — that is, have no actively replicating virus — but may or may not be “aviremic”.<\/p><\/blockquote>\n

So I feel a bit better.\u00a0\u00a0 Nonetheless, if you’re planning on introducing TaqMan into your clinic, prepare yourself for some significant patient education, reassurance — and stress management.<\/p>\n","protected":false},"excerpt":{"rendered":"

At our hospital lab, we recently switched from the bDNA viral load assay to the new Roche TaqMan real-time PCR test.\u00a0 The virologist in charge of our lab and the tech both agreed the assay was more accurate, more sensitive, and easier to do — so much so that we could increase the frequency of […]<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,5,8],"tags":[106,195,213,345,423,444,498,546,700,818,846,895,911,956,978],"class_list":["post-293","post","type-post","status-publish","format-standard","hentry","category-hiv","category-infectious-diseases","category-patient-care","tag-bdna","tag-clinical-significance","tag-colleague","tag-false-positives","tag-hiv","tag-hiv-rna","tag-infectious-diseases","tag-lab","tag-patient-care","tag-roche","tag-sensitive-assay","tag-taqman","tag-test","tag-undetectable-viral-load","tag-viral-replication"],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/wp-json\/wp\/v2\/posts\/293","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/wp-json\/wp\/v2\/comments?post=293"}],"version-history":[{"count":0,"href":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/wp-json\/wp\/v2\/posts\/293\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/wp-json\/wp\/v2\/media?parent=293"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/wp-json\/wp\/v2\/categories?post=293"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/wp-json\/wp\/v2\/tags?post=293"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}