A93 LATENT TUBERCULOSIS SCREENING PRIOR TO BIOLOGICAL THERAPY IN INFLAMMATORY BOWEL DISEASE PATIENTS: IS THE CHEST X-RAY ALWAYS NEEDED?

Abstract Background Inflammatory bowel disease (IBD) patients undergoing treatment with biological therapy are at increased risk of developing opportunistic infections such as tuberculosis (TB). Screening for latent tuberculosis is mandatory before initiating biological therapy such as Anti-TNF alpha. Most IBD guidelines include QuantiFERON Tb Gold (QTF), Tuberculin Skin Test (TST) and/or chest X-ray as screening methods. Aims The primary objective of this study was to compare if the chest X-ray in combination with QTF or TST is better in screening latent tuberculosis than QTF or TST alone in our IBD population. Methods We performed a retrospective descriptive monocentric study including in our source population all patients who started a biological treatment, followed at the IBD clinic of the CHUM between 2016 and 2018. We used the local IBD clinic database to collect the data. The study population included all patients who had a chest X-ray and QTF or TST done in the days, weeks or months preceding the institution of a treatment with biologics. The primary objective was to compare the sensitivity and specificity of a screening with QTF or TST alone as opposed to the gold standard (a combined screening that includes a chest X-ray). Results All patients in our source population were included in the study (n=164). Among them, 144 patients were screened with a chest X-ray plus QTF and 20 patients with a chest X-ray plus TST (53% men, 72% with Crohn’s, 82% Caucasian). All patients in the TST group (n=20) had a negative screening with both TST and chest X-ray. In the QTF group, 132 had a negative result, 10 had an indeterminate result and 2 had a positive result. Among patients with a positive QTF, the chest X-ray was negative and were considered positive for latent tuberculosis by the treating team. No cases of latent tuberculosis were found in the negative and indeterminate QTF groups. The sensitivity, specificity, PPV and NPV of the QTF test were all equal to 100% compared to the gold standard. A median follow up of 11.4 months after initiating biological therapy did not highlight any new cases of active or latent tuberculosis within our population. Conclusions In our population including mostly Caucasian patients without other risk factors for latent TB, the chest X-ray in combination to QTF or TST was not better than QTF or TST alone. These results should make us think over the current clinical practices that include chest X-ray in all patients for latent TB screening. Funding Agencies None