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| Tuberculin Skin Test (PPD) -Photo: CDC |
As an infectious diseases physician and hospital epidemiologist, I have heard over and over how difficult it is for the hospital’s employee health to TB screen our employees yearly with a PPD skin test.
Enter a new tuberculosis screening strategy for healthcare workers recently published in the Journal of Hospital Infection.
Japanese investigators integrated chest CT scans and the QuantiFERON®-TB Gold (QFT-G) test into their healthcare worker TB screening program. First, contacts were tested using the QFT-G test. Those positive for the QFT-G test were investigated by CT and classified as having active, latent, or old TB. A total of 512 healthcare workers with close or high risk contacts were identified, and underwent screening. Out of those, 34 (6.64%) were QFT-G positive, whereas 478 (93.36%) were negative. Of the 34 QFT-G-positive HCWs, four had CT findings compatible with active TB and received multidrug treatment; 24 showed no findings of active TB and received isoniazid for six months. All completed their regimens without any adverse effects.
Sounds excellent, however, several questions remain.
- How many healthcare workers with latent TB would have been missed by the traditional PPD skin testing?
- How many cases of active TB would have been missed by PPD testing, chest X-ray and symptom review?
- What is the cost/benefit of this new approach?
- Perhaps the Japanese are more disciplined and compliant with mandated employee screening. We cannot even get many of our healthcare workers to receive an influenza vaccine or have a PPD placed and read. How are we going to convince them to have serum drawn and undergo a CT scan?
I am by no means a big fan of the PPD skin testing. As a screening test, the PPD is insensitive and unreliable.
This new approach may be much more sensitive yet not feasible.
