Guidelines of the Israeli Association of Rheumatology for the prevention of tuberculosis in patients treated with Tnf-Á blockers

The use of TNFa blockers is associated with reactivation of tuberculosis. The Israeli Association of Rheumatology nominated a committee to determine guidelines for the prevention of tuberculosis in patients taking TNFá blockers. The risk of reactivation of tuberculosis is higher with monoclonal antibodies to TNFá (infliximab, adalimumab) in comparison with the soluble receptor of TNFá (etanercept). All patients who are candidates to receive TNFá blockers should be screened for active or latent tuberculosis. The screening includes: Tuberculin Skin Test (TST), chest X-ray and a questionnaire about possible exposure to tuberculosis. Two-step screening should be used as recommended by the Ministry of Health. The reaction elicited in the second test (if applied) should be used. In the general population latent tuberculosis is diagnosed when the TST response is 15 mm. or above; a reaction of 10 mm. or above is positive in populations with a history of definite or probable exposure to TB and 5 mm. is the threshold for populations who are immunosuppressed or if chest radiography reveals old tuberculosis without clear documentation of previous treatment. Patients with a TST less than 5 mm. should be questioned about prior exposure to tuberculosis. Latent tuberculosis should be treated with a 9 month course of isoniazid (300mg/d) or a 4 month course of rifampicin (600mg/d) or for 3 months with a combination of 300 mg. isoniazid and 600 mg. rifampicin daily. The committee recommends postponing treatment with TNFá blockers until completion of anti-tuberculosis therapy. If the clinical condition requires the urgent use of TNFá blockers, these may be initiated one month after starting treatment for latent tuberculosis.