Prednisolone treatment does affect the performance of the QuantiFERON in-tube test and the tuberculin skin test in patients with autoimmune disorders screened for latent tuberculosis

Background: During screening for latent tuberculosis infection (LTBI), before anti-TNF-alpha treatment, most patients are already receiving immunosuppressive therapy. Objective was to evaluate the performance of the QuantiFERON In-Tube (QFT-IT) and the Tuberculin Skin Test (TST) in these groups Methods: We included 248 patients with Ulcerative Colitis, Crohns disease, rheumatoid arthritis, and spondylo-arthropathy. Results: QFT-IT was positive in 7/248 (3%), negative in 229 (92%), and indeterminate in 12 (5%). TST was positive in 54/238 (23%) patients. Chest X-ray was suspect in 5/236 (2%), and 35/167 (21%) had risk-factors. We found a pronounced negative effect on QFT-IT and TST performance associated with prednisolone treatment; the IFN- response to mitogen stimulation was impaired (median IFN- response 4.9IU/ml (IQR0.8-10.0)) compared to patients a) not receiving corticosteroids (median 10.0 (IQR 5.0-10.0) (p=0.0015) or b) receiving long-acting corticosteroids (median 10.0 (IQR 9.7-10.0) (p=0.0058). Prednisolone treatment was strongly associated with negative TST, AOR 0.22 (0.1-0.8 (p= 0.018), and with an increased risk of indeterminate QFT-IT results AOR (16.1-69.0) p=0.001). No negative effect was found for long-acting corticosteroids. Prednisolon doses above 10 mgresulted in 27% indeterminate results. Conclusion: Oral prednisolone severely suppressed QFT-IT and TST performance whereas long-acting corticosteoroids, Metotrexate, Azathioprin and 5-ASA did not have similar detrimental effect. Patients should be screened for LTBI with QFT-IT or TST prior to initiation of prednisolone.