Prevention of Tuberculosis in Patients Treated With Biological Therapies: 20 Years' Experience in a Specialized Tuberculosis Clinic in a Low-prevalence Country

BACKGROUND: This study builds on previous evidence to assess the risk of tuberculosis (TB) in patients treated with biologic therapies (BioT), the role of the interferon-γ-release assay (IGRA) QuantiFERON-TB (QFT) Gold as a stand-alone screening test, and whether periodic re-testing is warranted for patients with a negative pre-BioT screening. METHODS: A total of 1368 patients starting BioT were screened for TB infection using 4 screening strategies over 4 consecutive periods: (1) 2-step tuberculin skin test (TST); (2) 2-step TST plus QFT Gold In-Tube; (3) single-step TST plus QFT Gold In-Tube; and (4) QFT Gold In-Tube (or QFT Gold Plus) alone. All patients with TB infection were offered preventive therapy. RESULTS: TB infection was diagnosed in 327 (23.9%) patients (40.8%, 39.5%, 25.3%, and 14.8% in the first, second, third, and fourth periods, respectively; P = .000). The adjusted odds ratios (ORs) with respect to the first period were 0.89 (95% CI, .55-1.44), 0.49 (95% CI, .33-.73), and 0.23 (95% CI, .15-.36) for the second, third, and fourth periods, respectively. During follow-up, 11 patients (0.8%) developed TB. The probability of remaining TB-free after 11 years of BioT exposure was 99.1%, with no significant differences between screening periods (P = .372). All TB cases in patients with negative baseline screening occurred within the first year of BioT exposure. CONCLUSIONS: Although BioT-associated TB can be significantly reduced, it is not completely preventable. Neither dual testing nor periodic systematic re-screening for TB infection is warranted after a negative pre-BioT test.