The prevalence of tuberculosis (TB) in rheumatoid arthritis (RA) patients is higher than that in the general population, and RA patients are considered a high-risk group. Currently, TB screening of RA patients receiving immunosuppressive therapy such as tumor necrosis factor-α (TNFα) antagonists is performed by the tuberculin skin test (TST) in Japan. Interferon-gamma release assays (QuantiFERON®-TB Gold In-Tube [QFT] and T-SPOT.TB®) are new alternatives to the TST to diagnose latent TB infection (LTBI) and active TB, and offer higher specificity and no cross-reactivity with Bacillus Calmette-Guérin (BCG) vaccine. We evaluated the cost effectiveness of QFT versus TST in non-BCG-vaccinated and BCG-vaccinated RA patients.
We constructed a Markov model to evaluate the cost effectiveness of QFT and TST. The target population is a hypothetical cohort of 1000 RA patients, using a societal perspective and the lifetime horizon. All costs and clinical benefits were discounted at a fixed annual rate of 3%.
In base-case analysis, the QFT strategy was the most cost effective ($US1044.52; 23.03499 quality-adjusted life-years [QALYs]) compared with the TST strategy for non-BCG-vaccinated RA patients ($US1824.61; 22.98153 QALYs) and for BCG-vaccinated RA patients ($US2096.34; 22.98153 QALYs) [year 2009 values]. The incidence of TB in RA patients with TNFα antagonist therapy influenced the cost effectiveness. When the incidence of TB in RA patients with TNFα antagonist therapy is under 0.00066, the TST strategy is more cost effective than the QFT strategy.
QFT screening is more effective and less costly than the TST for both BCG-vaccinated and non-BCG-vaccinated RA patients prior to TNFα antagonist therapy in Japan. These findings may be applicable to other countries when choosing optimal LTBI screening of RA patients.