Tuberculin test conversion in patients with chronic inflammatory arthritis receiving biological therapy

The blockade of inflammatory mediators produced by biological therapies is associated with an increased risk of opportunistic infections, as for example Mycobacterium tuberculosis (MT). Given the endemic situation of tuberculosis (TB) in some countries and immunosuppression/anergy of patients with chronic inflammatory arthritis, we wonder whether it is necessary to monitor the MT infection after starting the biological treatment. To evaluate the frequency of the tuberculin skin test (TST) conversion and its association with an active TB infection and other disease variables.

Patients with rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), and spondyloarthritis (SpA) receiving treatment with anti-TNF, tocilizumab, and/or abatacept agents were included into the study. Patients had to have a negative TST (<5 mm) at the baseline, and a second TST was performed 2-22 months after the initiation of biologic therapy. The TST conversion was considered as a variation ≥5 mm between the two TSTs performed within an interval between 2 months and 2 years.

A total of 85 patients were included into the study, and 78.8% were women, with a median schooling duration of 12 years. A total of 74.1% of patients had RA, 16.5% psoriatic arthritis, and 4.7% AIJ and ankylosing spondylitis. Regarding treatment, 75.3% received anti-TNF therapy (31.8% etanercept, 21.2% adalimumab, 17.6% infliximab, 3.5% golimumab, and 1.2% certolizumab), 15.3% tocilizumab, and 9.4% abatacept. Eight patients (9.4%) developed a TST conversion. The shift was more frequent in men (62.5%) than in women (37.5%) (p=0.009), and in those with a prolonged disease duration (X 226±109 vs X130±105 [p=0.017]). This association remained after adjusting for other variables. All patients who developed a TST conversion received prophylactic isoniazid, and only one patient with other risk factors developed active TB.

The frequency of a TST conversion in patients with chronic inflammatory arthritis was low and was associated with male gender and longer disease duration.