Latent tuberculosis infection screening prior to biological treatment in Tunisian patients

The screening of latent tuberculosis infection (LTBI) is necessary to prevent infection in patients with chronic inflammatory disease (CID) undergoing biological treatment. We aimed to assess the efficacy of LTBI screening prior to biological treatment in Tunisia, considered as a high-incidence area of active TB disease.

We conducted a retrospective study over a period of 8 years [2007-2014] including patients with chronic inflammatory rheumatism receiving biologic agents since at least 6 months. The screening of LTBI was performed according to national Tunisian guidelines.

There were 35 men and 78 women. The mean age was 47.67±13.50 years. Rheumatoid arthritis (70.8%) was the most common cause of CID. The diagnosis of LTBI was established in 23 cases. Among these 23 patients, 12 patients had negative tuberculin skin test (TST) associated with positive QuantiFERON-TB Gold (QFT-G), 10 had TST more than 10mm, one patient had a TST between 5 and 10mm associated with positive QFT-G and one patient had a history of tuberculosis inadequately treated. Preventive anti-tuberculous therapy was prescribed before biological therapy initiation in cases of LTBI. During the follow-up period (3.91 years), no case of tuberculosis reactivation has been reported among patients diagnosed with LTBI. However, 2 cases of active pulmonary tuberculosis were reported in patients with initially negative TST and QFT-G.

Our study showed that the Tunisian recommendations allowed detecting a LTBI in 20% of biologic therapy candidates. Preventive measures including screening of LTBI and eventually a prophylactic treatment improve the safety of biological treatments.