[Can an individual with a positive baseline QuantiFERON test result develop active tuberculosis?].
OBJECTIVE
QuantiFERON-TB Gold (QFT-G) test has been recommended as a new tool for the diagnosis of latent tuberculosis (TB) infection. However, the risk of development of active TB in the future depends on the period after the infection. The aim of this study was to evaluate the risk of development of active TB in individuals who have been infected.


METHODS
Clinical development of TB in subjects with positive baseline QFT test results was retrospectively analyzed. The subjects included healthcare workers, since 2003, at the Fukujuji Hospital who were examined at employment.


RESULTS
In total, 667 subjects were examined using the QFT-2G test, and 62 subjects were QFT positive at the first examination. One was treated using isoniazid, and 61 subjects were followed up for an average of 4.7 years (286 person-years). None of the subjects developed active TB during the observation period, and the probability of clinical breakdown (95% confidence interval) was 0-0.0104/person-year.


CONCLUSIONS
The risk of development of active TB among subjects with positive QFT-G test results at baseline was low. Treatment of latent TB infection is not recommended, unless an individual has been recently infected.
Fukujuji Hospital, Japan Anti-Tuberculosis Association. yi-lina@hotmail.com
Lina
L
Yi
Takashi
T
Yoshiyama
Masao
M
Okumura
Hideo
H
Ogata
Shoji
S
Kudoh
D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis*; D055985:Latent Tuberculosis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014374:Tuberculin Test / Q000379:methods*
D007371:Interferon-gamma