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.