Use of interferon gamma release assay to assess latent tuberculosis infection among healthcare workers in Hong Kong
DNC Tsang, CKC Lai, WC Yam, JWM Chan, YW Mok, WH Seto, SC Fung, CM Chu, BHS Lam, TK Ng
Department of Pathology, Queen Elizabeth Hospital
Key Messages
1. Overall baseline interferon gamma release assay positivity was 20.7%.
2. The conversion to interferon gamma release assay positivity at 3 months was 8.85% in the exposed group and 4.54% in the non-exposed group using the conventional cut-off of 0.35 IU/mL.
3. When grey zone results (0.2I-0.7 IU/mL) were included, the proportion of non-specific conversions and reversions could be reduced.
4. Interferon gamma release assay can be an adjunct tool in contact investigation of latent tuberculosis infection in healthcare workers.