Changing rate of serious infections in biologic-exposed rheumatoid arthritis patients : data from South American registries BIOBADABRASIL and BIOBADASAR

Most reports on serious infections (SI) in rheumatoid arthritis (RA) patients treated with biological disease-modifying antirheumatic drugs (bDMARDs) are from the USA and Western Europe. Data from other regions are largely missing. We report data from South American countries with different backgrounds and health-care systems but similar registries. We merged 2010-2016 data from two registries, BIOBADABRASIL (Brazil) and BIOBADASAR (Argentina), which share the same protocol, online platform and data monitoring process. Patients with active RA were included when they began the first bDMARD or a conventional synthetic DMARD (csDMARD, control group). The SI incidence rate (IR) per 1000 patient/years and adjusted IR ratio (aIRR) were estimated for bDMARDs and csDMARDs. Data were analysed for 3717 RA patients with an exposure of 13,380 patient/years. The 2591 patients treated with bDMARDs (64% tumour necrosis factor-alpha inhibitors (TNFi)) had a follow-up of 9300years, and the 1126 treated with csDMARDs had an exposure of 4081 patient/years. The SI IR was 30.54 (CI 27.18-34.30) for all bDMARDs and 5.15 (CI 3.36-7.89) for csDMARDs. The aIRR between the two groups was 2.03 ([1.05, 3.9] p=0.034) for the first 6months of treatment but subsequently increased to 8.26 ([4.32, 15.76] p<0.001). The SI IR for bDMARDs decreased over time in both registries, dropping from 36.59 (28.41-47.12) in 2012 to 7.27 (4.79-11.05) in 2016. While SI remains a major concern in South American patients with RA treated with bDMARDs, a favourable trend toward a reduction was observed in the last years3882129213