Tuberculosis screening at the Sainte-Anne Hospital in Paris – results of first and second IGRA

INTRODUCTION Healthcare workers (HCWs) are exposed to Mycobacterium tuberculosis (MTB) and therefore are screened for tuberculosis (TB). Results of TB screenings with the Interferon-γ Release Assay (IGRA) in a French psychiatric hospital without a TB ward are described. METHODS At the Sainte-Anne Hospital, a referral centre for psychiatric patients throughout the municipal region of Paris, IGRA screening is performed during pre-employment and general health examination or after potential contact to MTB. The QuantiFERON Gold in tube (QFT) is used and data on TB history are assessed in a standardized manner. RESULTS Between August 2008 und August 2013 in total 1.192 HCWs were tested and the QFT was positive in 265 (22.2%). Probability of a positive QFT increased with age. A second QFT was performed in 144 HCWs with a positive QFT and 53 (36.8%) HCWs had a reversion. With a positive QFT close to the cut-off (e.g. 0.35-0.7 IU/ml) the odds ratio for a reversion was 4.6 compared to an INF-γ concentration of ≥3.0 IU/ml. Probability of reversion was not influenced by preventive chemotherapy, which was completed by 28 (19.4%) HCWs with a positive QFT. No active TB was detected. CONCLUSION Prevalence of positive IGRA is high in French HCWs as is the number of reversions in IGRA. Reversion rate is particularly high around the cut-off of the IGRA. A borderline zone will therefore reduce the influence of test variability.