How useful is chest X-ray in addition to routine QuantiFERON® in the detection of latent tuberculosis prior to biologics?

Screening with QuantiFERON®/interferon-γ release assay (IGRA) and chest X-ray (CXR) for latent tuberculosis (TB) infection is recommended by the British Association of Dermatologists prior to commencing some biologics. QuantiFERON is highly sensitive, while CXR is poorly sensitive and poorly specific. In our cohort of 995 patients, 2.3% had a positive IGRA and 8.7% had any abnormality on CXR, with only 0.8% suggestive of TB. Patients were just as likely to have an abnormal CXR if they had a positive or negative IGRA (P = 0.93). We suggest that routine screening with IGRA alone is sufficient in the dermatology population, particularly in the setting of a low TB incidence country such as the UK.