Why choose a 2-step TB skin test vs. TB blood test?

[micheljd]

For anyone who has had a TST (TB skin test), I am curious what advantages a TST test has over an IGRA (TB blood test).

It seems like, in general, TB skin tests are more painful than a blood draw (although many people don't experience too much pain). A person needs two skin injections (for a 2-step test), as opposed to one blood draw.

There are also more side effects for a TB skin test, such as blistering, itchiness, and a risk for allergic reaction (many places require epinephrine available just in case). Although those side effects doesn't happen to everyone, it seems much more likely than a side effect to a blood draw.

The IGRA is generally more accurate than TB skin testing, and the test can be completed in one visit, instead of four. Many studies have shown IGRAs to be more cost-effective long-term for employers.

I know many people don't find two skin tests to be a big deal, but I am interested in why a person would choose two skin tests over one blood draw. The CDC has stated the two are always interchangeable, and I am not aware of any place that only accepts skin tests (even if they don't mention the other options). If an employer or health insurance is paying, why do people choose a 2-step skin test?

[brillohead, ADN, RN]

I got a TB blood test because i kept forgetting to go back and get it read in Time. Cost ended up less for me. TB test for admin and reading at CVS was over 50 bucks and i had to get 2 of them. I ordered the TB blood Test online through Order any Lab Titers, Wellness Labs, STD test and more online. – LabReqs.com and cost for TB blood test was $129.00. C

I don't understand your math. Skin test @ $50 x 2 = $100. Blood test = $129. How is the blood test cheaper?

[Nurselizzy757]

I've always heard that getting TB skin tests will, over time, cause one to eventually test positive, because of the repeated exposure. Then would need to get a CXR to rule out latent infection. Anyone have an opinion on this?

[TriciaJ, RN]

I've always heard that getting TB skin tests will over time cause one to eventually test positive, because of the repeated exposure. Then would need to get a CXR to rule out latent infection. Anyone have an opinion on this?

This is news to me. I think when people eventually test positive it's because they've had an exposure. That's why high risk workplaces require yearly testing. It's not their yearly tests that cause them to convert.

[chare]

I don't understand your math. Skin test @ $50 x 2 = $100. Blood test = $129. How is the blood test cheaper?

When you compare going once and having blood drawn (cost $100 - $200), and viewing results online via patient portal with getting PPD ($50) going back in 48 - 72 hours for results, then doing this again ($50) in 2 - 4 weeks. For me, it's worth the additional $100 for the time and aggravation saved.

[JBMmom, MSN, NP]

I had the quantiferon gold for school because of a past positive with PPD, and they wouldn't accept a 4 month old chest x-ray. Apparently that test can also be challenging to ship/process correctly and my first one came back inconclusive because the controls failed. So, I had to eat the cost for two tests, at least now I have an employer that will cover it annually. I would definitely prefer the PPD if I weren't going to be flaming positive annually.

[CharleeFoxtrot, BSN, RN]

Another reason to go with the blood draw is that a person may have to have the blood test because they are immune compromised and the Mantoux test is contraindicated.