BACKGROUND: The reactivation rate of tuberculosis in patients with chronic inflammatory arthritis (CIA) on TNFα inhibitors (TNFi) and baseline negative screening for latent tuberculosis infection (LTBI) is higher than in the general population.
OBJECTIVE: To compare the performance of tuberculin skin test (TST), TST-Booster, ELISPOT (T-SPOT.TB) and QuantiFERON-TB Gold in tube (QFT-IT) to detect LTBI in patients with CIA on TNFi.
METHODS: A total of 102 patients with CIA [rheumatoid arthritis (RA), n = 40; ankylosing spondylitis (AS), n = 35; psoriatic arthritis (PsA), n = 7; and juvenile idiopathic arthritis (JIA), n = 20] were prospectively followed-up for 24 months to identify incident LTBI cases. Epidemiologic data, TST, T-SPOT.TB, QFT-IT and a chest X-ray were performed at baseline and after 6 months of LTBI treatment.
RESULTS: Thirty six percent (37/102) of patients had positive TST or Interferon Gamma Release Assays (IGRAs) tests. Agreement among TST and IGRAs was moderate (k = 0.475; p = 0.001), but high between T-SPOT.TB and QFT-IT (k = 0.785; p < 0.001). During the 24-Month follow-up, 15 (18.5%) incident cases of LTBI were identified. In comparison to TST, the IGRAs increased the LTBI diagnosis power in 8.5% (95% CI 3.16-17.49). TST-Booster did not add any value in patients with negative TST at baseline. After 6-Month isoniazid therapy, IGRAs results did not change significantly.
CONCLUSIONS: Almost 20% of CIA patients had some evidence of LTBI, suggesting higher conversion rate after exposition to TNFi. TST was effective in identifying new cases of LTBI, but IGRAs added diagnostic power in this scenario. Our findings did not support the repetition of IGRAs after 6-Month isoniazid therapy and this approach was effective to mitigate active TB in 2 years of follow-up.

The interferon-γ release assays as potent adjunct tools for the quick detection of TB in high burden countries is feasible. In this retrospective study, we aimed to identify the risk factors for negative T-SPOT results in confirmed active tuberculosis.
We consecutively enrolled 1,021 patients who were positive for acid-fast bacilli smear staining or culture-confirmed mycobacterial infection and simultaneously tested with the T-SPOT.TB assay. All of the included specimens were used to discriminate the Mycobacterium species using the biochip assay. We collected basic clinical characteristics and laboratory results for further analysis.
Of the 1,021 patients enrolled in the study, 89 patients were identified as having nontuberculous mycobacteria (NTM). Ninety-nine patients were excluded from the analysis because of indeterminate T-SPOT.TB results, while the remaining 833 patients were identified as having Mycobacterium tuberculosis infection. In total, 159 patients had false-negative T-SPOT.TB results (19.1% of 833). The concordance rate between the T-SPOT.TB results and final diagnoses in females was always lower than that in males. Multivariate logistic regression analysis showed that female sex (OR 1.81; 95% CI 1.19, 2.7; p = 0.006), age (OR 1.02; 95% CI 1.01, 1.03; p = 0.003), acid-fast bacilli (AFB) smear-negative (OR 5.45; 95% CI 3.62, 8.19; p < 0.001), HIV coinfection (OR 6.83; 95% CI 2.73, 17.10; p < 0.001) were associated with negative T-SPOT.TB result.
Female is another independent risk factor of negative T-SPOT.TB results, besides to elder, HIV co-infection, acid-fast bacilli (AFB) smear-negative who are suspected of having active TB infection.

BACKGROUND: The extent to which anti-tumor necrosis factor (TNF)-associated tuberculosis can be prevented is unclear, and there is no established guidance on the optimal screening strategy for latent tuberculosis (LTBI) in patients about to start anti-TNF therapy. We aimed to determine the effectiveness of a comprehensive program for the prevention of anti-TNF-associated tuberculosis, and to evaluate 3 LTBI screening strategies and the need for retesting patients with negative results at baseline.
METHODS: In total, 726 patients were screened prior to anti-TNF therapy using 1 of 3 diagnostic strategies over 3 consecutive periods: first, a 2-step tuberculin skin test (TST); second, a 2-step TST plus QuantiFERON-TB Gold In-Tube test (QFT-GIT) (2-step TST/QFT); and third, a single-step TST plus QFT-GIT (TST/QFT). Infected patients were offered preventive therapy. We assessed differences in the incidence of tuberculosis between anti-TNF exposed and nonexposed patients, and between the 3 study periods.
RESULTS: Tuberculosis developed during the first year in 2.85 per 1000 exposed patient-years (3/1052 patient-years) and 1.77 per 1000 nonexposed patient-years (1/566 patient-years). No cases occurred beyond the first year of treatment. LTBI diagnoses decreased with the single-step TST/QFT (26.5%) compared with the 2-step TST (42.5%; P < .001) and 2-step TST/QFT (38.5%; P = .02); the incidence of tuberculosis among exposed patients did not change significantly across the 3 periods (2.63/1000, 3.91/1000, and 2.4/1000 patient-years, respectively).
CONCLUSIONS: Although anti-TNF-associated tuberculosis can be reduced, some risk remains during the first year of therapy. Neither the 2-step TST nor systematic retesting after negative baseline testing is justified.