Assessment and management of tuberculosis infection in patients due to start anti-TNF-a treatment

Abstract number: 1732_310

Casas S., Gasch O., Lora-Tamayo J., Reina D., Joanola X., Gonzalez L., Guerra M., Santin M.

Objectives: To evaluate a protocol for assessment of tuberculosis (TB) infection in patients due to start treatment with anti-TNF agents and to evaluate the efficacy and safety of chemoprophylaxis in anti-TNF treated patients.

Methods: Prospective evaluation of all patients referred to the Tuberculosis Unit of a third-level teaching hospital (Jan 2003–Oct 2006), for assessment of TB infection prior to initiation of anti-TNF treatment. Diagnosis of TB infection was based on anamnesis for TB risk, two step tuberculin skin testing (TST) and chest X-ray. Patients were followed up throughout the period of chemoprophylaxis and adherence was monitored by determining isoniazid metabolites in urine (or urine colour when appropriate). A positive TST was defined as an induration ≥5 mm.

Results: 210 patients, 64% women, mean age 52 years, were evaluated. Baseline illness: 60.5% rheumatoid arthritis, 13.8% cutaneous psoriasis, 13.3% psoriatic arthritis, 11% ankylosing spondylitis, and 1.4% Crohn's disease. Thirty-eight (80.2%) patients were on immunosuppressive treatment. Thirty-one (14.9%) patients had BCG-vaccination, 6 had been treated for TB, and 2 had prior positive TST. Of 201 patients who underwent TST, 84 (41.8%) resulted positive (59 and 25 in the first and second test respectively), and 117 (58.2%) resulted negative. Chemoprophylaxis was given to 79 (39.3%) patients: 78, isoniazid for 9 months and 1 rifampin for 4 months. Three patients (3.8%) experienced a 5-fold increase of transaminase level above the ULN. After a 237 patient–years follow up, one of the 130 patients who finally received anti-TNF treatment developed TB (0.42%; 95% CI: 0.01–1.71). His two-step TST resulted negative and he began on adalimumab. Five months later, TB developed.

Conclusion: Systematic and protocolised assessment for TB infection and its treatment when indicated is a reliable and useful method to prevent anti-TNF-associated TB. Our data show that two-step TST is helpful to detect TB infection in a significant number of patients. Prolonged treatment with isoniazid seems to be safe in anti-TNF treated patients.