Background Biologic agents have led to a sea change in the management of inflammatory arthritis however higher risk of opportunistic infections particularly tuberculosis (TB) is well recognised. This has led to the development of TB screening guidelines.
Objectives The aim of this study was to investigate the prevalence of latent TB in patients prescribed biologic therapy in a TB endemic area (prevalence 50/100,000) and to assess the risk of subsequent reactivation.
Methods Retrospective case note review of all patients with inflammatory arthritis ever prescribed biologic therapy between 1998 and 2014 at our centre.
Results 299 patients (109 men: 190 women) who have had biologic therapy over sixteen years were included. Mean age upon commencing the biologic was 51 years. 203 (68%) participants had rheumatoid arthritits, 30 (10%) psoriatic arthritis, 48 (16%) axial spondyloarthropathy and 18 (6%) juvenile idiopathic arthritis. 218 (73%) patients were Caucasian, 59 (20%) Asian, 15 (5%) Afro-Caribbean and the remaining 7 were mixed race. 239 (80%) prescriptions were issued for TNF inhibitors (98 for etanercept and remaining for monoclonal antibodies). 33 patients had rituximab, 17 had tocilizumab and 3 were initiated on abatacept. Seven had stopped TNF inhibitors. Median duration of biologic therapy was 4.2 years for those who remained on treatment prior to stopping or switching therapies.
Prior to the implementation of TB screening in the unit in 2007, 112 patients underwent clinical assessment, chest x-ray and check for BCG scar. One patient of Asian origin developed extra-pulmonary TB within six weeks of adalimumab initiation. Following a year of antiTB treatment, he restarted the biologic therapy with no ill effect. 187 participants underwent additional interferon gamma release assay (IGRA) testing as part of new protocol (T Spot test). 18 (10%) had positive test with normal chest xrays. Six patients were white, 9 of Asian origin and 3 others. Three Caucasian patients had borderline result. All had 3 months of isoniazid and rifampicin with simultaneous prescription of biologic agent (13 had TNF antagonist, 5 rituximab and 3 tocilizumab). No cases of active TB infection were observed.
Conclusions Prevalence of latent TB in patients with inflammatory arthritis prescribed biologic therapy in an endemic area is 10%. The risk is independent of ethnicity and warrants careful screen and monitoring in all patients. Adherence to strict screening protocol reduces the risk of active TB infection irrespective of the biologic therapy employed.
Disclosure of Interest None declared