Estimation of incidence of tuberculosis infection in health-care workers using repeated interferon-gamma assays.
The aim was to estimate the incidence of Mycobacterium tuberculosis (Mtb) infection in health-care workers (HCWs) in Japan. We repeated cross-sectional surveys of HCWs with QuantiFERON-TB Gold (QFT-G) in 2003, 2005 and 2007 at a hospital with tuberculosis (TB) wards, and 311 HCWs who underwent QFT-G testing two or three times were included in the study. Five HCWs (1.8%) converted from negative to positive. Incidence of new TB infection was estimated to be 0.6/100 person-years by the CDC's definition. Thirteen positive persons (41%) reverted from positive to negative. Multivariable logistic regression analysis identified a significant association between QFT-G conversion and working in TB wards. The IFN-gamma levels of all but two subjects with reverting or converting QFT-G results were close to the test's cut-off. The incidence of Mtb infection in HCWs at our hospital was higher than that estimated for the general population in Japan. Criteria for defining QFT-G conversion and reversion need further investigation considering the high proportion of reversion, as the incidence of infection would have changed if we had applied other definitions.
Yoshiyama
T
T
Fukujuji Hospital, Matsuyama, Kiyose, Tokyo, Japan. yoshiyama1962@yahoo.co.jp
Harada
N
N
Higuchi
K
K
Nakajima
Y
Y
Ogata
H
H
D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006282:Health Personnel; D006761:Hospitals; D006801:Humans; D015994:Incidence; D007371:Interferon-gamma / Q000097:blood*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D014376:Tuberculosis / Q000453:epidemiology*; D055815:Young Adult
D007371:Interferon-gamma