P124. Use of interferon-gamma release assay (IGRA) and tuberculin skin test (TST) for tuberculosis screening in patients candidates for anti-TNF terapy in inflammatory bowel disease (IBD)
S. Fernandez1, J. Riera1, N. Balza1, M. Garcia2, A. Serrano2, M. Trelles1, H.J. Canaval1, R. Chachi1, C. Dolz1, 1Hospital Son Llàtzer, Gastroenterology, Spain, 2Hospital Son Llàtzer, Internal Medicine, Spain
Both the Food Drug Administration (FDA) and the European Medicines Agency (EMEA) recommend performing screening to rule out latent tuberculosis infection (LTI) in patients who are treated with anti-TNF. The IGRA Quantiferon-TB-Gold in Tube® test (QFT-G-IT) in combination with the TST may be useful in detecting LTI in an intermediate-incidence country as ours. We intend to evaluate the use of QFT-G-IT in combination with the recommended tests in Spain (TST, TST retest, clinical data and Chest X-Ray) for LTI diagnosis in patients with IBD.
Observational study of all patients with IBD candidates for biologic therapy in our hospital from June 2008 to October 2012. Informed consent was obtained and the protocol was approved by the hospital ethics committee. The following data were collected: age, sex, immunosuppressive therapy, history of tuberculosis, history of vaccination (by scar on arm or buttock), TST, TST retest, QFT-G-IT and chest X-ray.
87 patients were recruited, 40 men (46%) and 47 women (54%) with a mean age of 39.84 years (range 16–74 years). The 62.1% had Crohn's disease, 35.6% had ulcerative colitis and 2.3% indeterminate colitis. The 96.6% had received immunosuppressive therapy. 23% were BCG vaccinated, 50.6% non-BCG vaccinated and 24.1% did not know. The TST was positive in 9 patients (10.3%), the TST retest became positive in 1 patient, and 3 patients (3.4%) were positive for QFT-G-IT (one of which had been negative TST retest). 11/87 had at least one of the two test positive, so LTI rate in our patients was 12.6%. Chest X-ray was normal in all cases. The index of agreement (Kappa) between TST and QFT-G-IT was low (Kappa = 0.121; standard error 0.261; 95% CI −0.391; 0.634). Among the 10 patients with a positive TST, there were 7 BCG vaccinated cases, all of them with a negative QTF-G-IT test.
There was a low rate of LTI in among IBD patients in our setting. The concordance between the two tests in IBD patients in our series is poor, especially in vaccinated patients. 2 of 11 patients have been diagnosed of LTI only by a positive QFT-G-IT. QFT-G-IT can be a useful tool that can optimize the diagnosis of LTI.