Clinical experience of QuantiFERON(®) -TB Gold testing in patients with psoriasis treated with tumour necrosis factor blockers in Taiwan

Abstract

Background: In Taiwan, an intermediate tuberculosis burden country, around 9·3% of patients with rheumatoid arthritis treated with adalimumab develop tuberculosis despite prescreening with the tuberculin skin test. Within the Asia-Pacific region, the tuberculosis risk in patients with psoriasis who use tumour necrosis factor (TNF) blockers is unknown.

Objectives: This study reports the use of QuantiFERON(®) -TB Gold (QFT-G) (Cellestis, Melbourne, Vic., Australia) as a screening method for latent tuberculosis infection (LTBI) in patients with psoriasis.

Methods: This retrospective review evaluated 216 patients with psoriasis in whom TNF blockers were considered between 2004 and 2009 in a tertiary referral hospital in Taiwan. Beginning in 2007, QFT-G was performed on all patients who were candidates for TNF blockers.

Results: Seventeen patients who used TNF blockers for less than 4 weeks were excluded. Of the 147 assessed patients receiving TNF blockers, 110 (75%) underwent QFT-G tests. A total of 126 (86%) patients used etanercept and 40 (27%) patients used adalimumab. Nineteen patients switched between both. Overall, patients had a median of 24 weeks (range 4-307) exposure to TNF blockers. Twelve patients (11%) who were treated with TNF blockers and eight (15%) without TNF blockers had positive QFT-G results. Of all TNF blocker users, only one patient (0·68%) developed tuberculosis.

Conclusions: QFT-G can be used to screen for LTBI in a tuberculosis endemic area where bacille Calmette-Guérin vaccination coverage is high. Isoniazid prophylaxis is recommended for those who have positive QFT-G test results.