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P096. Interferon-gamma release assays (T-SPOT.TB and QuantiFERON-TB GOLD in tube) versus tuberculin skin testing for detection of latent tuberculosis in patients with inflammatory bowel disease

R. De Francisco1, M. Arias2, A. Pando2, J. Palacios3, P. Escalante4, I. Perez-Martinez1, L. Rodrigo1, L. Molinos2, S. Riestra1

1Inflammatory Bowel Disease Unit, Hospital Universitario Central de Asturias, Oviedo, Spain; 2Respiratory Service, Hospital Universitario Central de Asturias, Oviedo, Spain; 3Microbiology Service, Hospital Universitario Central de Asturias, Oviedo, Spain; 4Pulmonary and Critical Care Service, Mayo Clinic, Rochester, MN, United States

Aim: The screening for latent tuberculosis infection (LTBI) in patients with inflammatory bowel disease (IBD) is mandatory prior to the start of anti-tumor necrosis factor-α (anti-TNFα). In Spain, official recommendations include chest-X ray and tuberculin skin test (TST); the role of interferon gamma release assay (IGRA) remains unclear in IBD patients. The aim of the study is to assess concordance between the two IGRA with TST in IBD patients.

Material and Methods: We aimed to evaluate the results of TST (retesting if the first one was negative) and two IGRA (T-SPOT.TB and QuantiFERON-TB GOLD In Tube) in 123 IBD patients recruited through an IBD outpatient clinic in Oviedo (Northern Spain). The three tests were performed simultaneously by the same trained nurse. Epidemiological and clinical data were recorded. Concordance between IGRA and TST was evaluated using kappa test.

Results: 123 patients were enrolled (92 CD and 31 UC); there were 66 women and 57 men with a mean age 42.6 years, smokers 43 (34%), mean disease duration 11.6 years and previous hospitalizations 98 (79.7%). In CD patients: previous surgery in 49 (53.3%), and CDAI at screening 122±90 (mean ± SD). In UC patients: extension was E2 (32.3%) and E3 (67.7%), with a Truelove score at screening 12.4±3.4 (mean ± SD). Treatment at the time of the screening was: no therapy 17, immunomodulators (IMM) (azathioprine or methotrexate) alone 46, IMM + steroids 19, IMM + anti-TNFα 6, anti-TNFα alone 14, anti-TNFα + steroids 3, steroids alone 15 and triple therapy 3. TST was positive in 36 (29.3%) out 123 patients. T-SPOT.TB was positive in 11 (8.9%), negative in 105 (85.4%) and indeterminate in 7 (5.7%). QuantiFERON was positive in 9 (7.3%), negative in 110 (89.4%) and indeterminate in 4 (3.3%). The concordance between TST and T-SPOT.TB was very low (kappa: 0.129, p: 0.076), between TST and QuantiFERON was low (Kappa 0.277, p < 0.001), and between T-SPOT.TB and QuantiFERON was moderate (Kappa 0.562, p < 0.001). Positive TST is more frequent in patients without treatment that in those receiving any type of treatment (41.4% vs. 27.4% [OR 1.86, IC 95%: 0.65–5.34]), p: 0.245. TST positive patients were older than negative (47±9 vs 40.8±14 years, p = 0.003), as well as positive QuantiFERON (49.4±14.9 vs. 42.5±12.8 years, p: 0.05).

Conclusions: In IBD patients of Northern Spain, TST is positive in 29.3% of them; there is a low concordance between TST and IGRA tests, and moderate concordance between the two IGRA studied (T-SPOT.TB and QuantiFERON).