[Update of the guidelines of the Israeli Association of Rheumatology for the prevention of tuberculosis in patients treated with TNF-alpha blockers].

The use of TNFalpha blockers is associated with reactivation of tuberculosis (TB). The previous guidelines of the Israeli Association of Rheumatology were based on the tuberculin skin test (TST), chest X ray and a questionnaire on possible previous exposure to TB. The growing use of Interferon-gamma released assay (IGRA) has prompted the need for an update to these guidelines. All patients who are candidates to receive TNFalpha blockers should be screened for active or Latent tuberculosis. The screening includes: Tuberculin Skin Test (TST), interferon-gamma release assays (IGRA), chest X-ray and a questionnaire about possible exposure to tuberculosis. TST > or = 10 mm is considered positive; TST < or = 5 is negative; in case of TST = 0, a 2-step screening is recommended. If TST is > or = 5 mm but < 10 mm or in heavy immunosuppressed patients with TST = 0, an IGRA test should be performed and the diagnosis of latent TB taken accordingly. If the IGRA test is indeterminate, the decision should be taken based on the TST and patient's characteristics. 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 (300 mg/d) or a 4 month course of rifampicin (600 mg/d) or for 3 months with a combination of 300 mg. isoniazid and 600 mg. rifampicin daily. The committee recommends postponing treatment with TNFalpha blockers until completion of anti-tuberculosis therapy. If the clinical condition requires the urgent use of TNFalpha blockers, these may be initiated one month after starting treatment for latent tuberculosis.