Background/Purpose: Anti-TNF agents have emerged as an important treatment for rheumatic diseases, particularly for ankylosing spondylitis (AS). Screening and treatment of latent tuberculosis infection (LTBI) is essential before the use of these drugs. However, current recommendationsfor this screening and treatment and their efficacy are still not well established in endemic regions. The purpose of the present study is to evaluate, in an endemic area, the efficacy of LTBI screening and treatment in AS patients under anti-TNF. 

Methods: One hundred and ten AS patients eligible for anti-TNF agents were initially screened for LTBI by tuberculin skin test (TST), chest X-ray and history of contact. Patients were regularly followed at 1-3 months interval, from June 2004 to January 2013.

Results: LTBI screening was positive in 48 (43.6%) patients. TST positivity accounted for majority of LTBI diagnosis (46; 95.2%): 39 (81.2%) solely positive TST, 6 (12.5%) with positive TST and history of contact, 1 (2.1%) with positive TST and abnormal chest X-ray and 2 (4.2%) with isolated history of contact. These patients received at least 1 month isoniazid before starting anti-TNF treatment and all of them completed 6 months of isoniazid treatment.Two patients developed TB in spite of LTBI treatment: one was a medical doctor with proven exposure to TB after 8 months receiving adalimumab, and the other became symptomatic right after the second dose of adalimumab, and probably had active TB that was misdiagnosed as LTBI. Sixty seven (60.9%) patients were treated with one anti-TNF, 33 (30%) with two and 10 (9.1%) with three (86 infliximab, 49 adalimumab and 75 etanercept). Thirty three (30%) patients were under prednisone, mean dose 10.6 mg/day. No difference was observed in TST positivity rate in this group comparing with the patients without this drug (48.5% vs. 39%, p=0.40). TST was repeated in 9/64 (14%) patients initially screened negative in case of prolonged discontinuation and reintroduction of biologic treatment (n=2) or clinical tuberculosis (TB) suspicion (n=7). In the latter group, TST conversion was observed in 3 patients diagnosed with active pulmonary TB. Median duration of anti-TNF treatment (2 adalimumab e 1 infliximab) in these three patients before the diagnosis of TB was 1.8 (0.6 – 3.5) years. 

Conclusion: Our study provides evidence that TBLI screening and treatment is also efficient for endemic areas. In addition, we report that new exposure accounts for nearly all cases of TB infection and further demonstrate that symptom guided TST repetition is very effective for TB diagnosis during anti-TNF therapy in high TB incidence region.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/latent-tuberculosis-screening-and-treatment-in-ankylosing-spondylitis-patients-eligible-for-anti-tnf-therapy-in-endemic-area/