{"id":5584,"date":"2014-11-10T18:13:52","date_gmt":"2014-11-10T23:13:52","guid":{"rendered":"http:\/\/blogs.nejm.org\/?p=5584"},"modified":"2015-06-04T14:31:59","modified_gmt":"2015-06-04T18:31:59","slug":"common-curbsides-the-tuberculin-skin-test-and-igra-that-dont-agree","status":"publish","type":"post","link":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/common-curbsides-the-tuberculin-skin-test-and-igra-that-dont-agree\/2014\/11\/10\/","title":{"rendered":"Common Curbsides: The Tuberculin Skin Test and IGRA That Don’t Agree"},"content":{"rendered":"

\"louie<\/a>Here’s one I’ve received twice in the past week, plus my answer.<\/p>\n

As always, names\/some details changed to protect patient confidentiality, plus my annotations in brackets\/italics.<\/p>\n

Hey Paul,
\nQuick question [Need I even comment about the “quick question” phrase, and how this unintentionally devalues what ID docs\u00a0do? OK, I’ve commented, and yes I’m hypersensitive]<\/em>\u00a0— one of my patients, a 38-year-old woman from Serbia, is about to start biologics\u00a0for rheumatoid arthritis [you can see this is going to be a latent tuberculosis testing question from miles away].<\/em>
\nShe’s not sure if she got BCG as a child [yep, called that one]<\/em>, so I did\u00a0both [uh-oh]<\/em> a PPD and sent a quantiferon gold [note this is not the crazy alphabetizing\u00a0of the branded interferon gamma release assay (IGRA) products, which for some reason is “QuantiFERON<\/span>\u00ae-TB\u00a0<\/span>Gold<\/span>“<\/span>\u00a0or the other one, which just goes with all-caps, “T-SPOT.TB”, and\u00a0throws a period in the middle — jeeze, marketers]<\/em>. The PPD is positive at 20 mm, but the quantiferon is negative [of course — otherwise there’s no question].<\/em> Her CXR is negative.
\nMy conclusion is that she does not have TB and therefore does not need preventive therapy prior\u00a0to starting biologics [that’s notable — putting your money down!]<\/em>. Is that the correct conclusion?
\nI’m sure this is a very easy question\u00a0[ah, not so easy after all]<\/em> as you must get it all the time [second part is most certainly true].<\/em>
\nThank you very much sir [so formal! or maybe he was in the military]<\/em> for your time.
\nArchie\u00a0[not his real name, but\u00a0it was the name of a dog we had growing up, a long-haired dachshund]<\/em><\/p>\n

As noted above, nope, not so easy. Let’s consider the variables:<\/p>\n