Effectiveness of a tuberculosis screening program in rheumatic patients treated with immunossuppressants

Background: Immunosuppressants, including new biological therapies, enhance the risk of developing active tuberculosis (TB). An effective screening program is essential. Aim: To investigate the impact of a TB screening program on the development of active TB in rheumatic patients treated with immunosuppressants. Methods: Retrospective analysis of patients followed at Portuguese Institute of Rheumatology, screened for latent or active TB in the Pulmonology Diagnostic Center, since february 2005. The evaluation included clinical history, tuberculin skin test, chest x-ray, interferon gamma release assay and chest CT according to protocol. If any of these was positive, 9 months isoniazid (INH) and piridoxin was prescribed. If all were negative, patients remained under biannual monitoring. Results: The study had 641 patients with 471 females and mean age 52±13 years. The average length of follow-up was 2,8±1,4 years. Main rheumatological diagnoses were rheumatoid arthritis (n=394), ankylosing spondylitis (n=104) and psoriatic arthritis (n=70). 173 were candidates to biological therapy and 468 were proposed or already treated with classic immunosuppressants. 532 patients were prescribed INH, of whom 14 refused and 10 suspended for intolerance (9 hepatotoxicity and 1 medullar aplasia). The remaining 109 were proposed only for clinical monitoring. No patient developed TB after the screening program. Conclusion: In this population, 80% required chemoprophylaxis with INH and only 0,02% developed intolerance. The TB screening program used was effective, with no cases of TB reported, however these results did not allow calculating its impact in reducing the risk of TB.