Background:In the recent decades, biological disease-modifying antirheumatic drugs (bDMARDs) have significantly improved management and quality of life in patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA).However, bDMARDs have also a strong influence on the immune system, leading to a risk of serious infection. Reactivation of hepatitis B (HBV) and C (HCV) virus is one of the most redoubtable complications of these immunosuppressive agents.Objectives:The aims of this study were to determine the screening rate for hepatitis B and C before starting a biological treatment and to examine the prevalence of their markers in patients with RA or SpA.Methods:Our study evaluated all patients included in the Tunisian registry BINAR (Biologic National Registry) since 2018 who had RA (ACR/EULAR 2010) or SpA (ASAS criteria) aged with more than eighteen years old and receiving their first bDMARDs during the two past years.The following information were retrieved from the registry: demographic data on the patients, disease parameters, medication, HBV surface antigen (HBs Ag), antibody to HBs Ag (Anti HBs), antibody to HBV core antigen (Anti HBc), HBV-DNA, antibody to HCV (anti HCV) status and liver function tests (AST: aspartate aminotransferase; ALT:alanine aminotransferase).Results:A total of 298 patients was included, 111 men and 178 women, with a mean age of 49.2 ± 14.1 years old [18-79]. Among them, 58.7% were diagnosed with RA and 41.3% were diagnosed with SpA. The mean disease duration was 6.7±3.5 years [1-12] in patients with RA and 6.5±3 [1-12] in patients with SpA. The mean Disease Activity Score (DAS28) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) were respectively of 4.9±1.5 [1-8] and 4.1±1.8 [0-9].Therapeutically, 167 patients (56%) were on Prednisone at a mean daily posology of 8.2±5.4 mg [4-60] and 70.3% on conventional synthetic disease modifying antirheumatic drug (csDMARD) in association with bDMARDs. It was about Tumor Necrosis Factor alpha antibodies (anti TNF a) in 87.9% of cases, Tocilizumab in 10.4% of cases and Rituximab in 5% of cases.A screening of HBV was performed in 286 patients (96%). Ag HBs was positive in two cases (0.7%), and anti-HBc was positive in 16 cases (6.4%) which indicate a prior HBV infection. Fifteen patients (6%) were immunized with positive anti HBs. HBV-DNA was measured in 177 cases (66.8%) and was positive in 15 patients (6%).HCV infection was searched in 282 patients (94.6%) and anti-HCV was negative in all cases.AST and ALT mean rates were respectively of 18.3 [2-108] and 17.9 UI/l [2-74]. A perturbation of these liver function tests was observed in 13 patients (4.4%).Conclusion:Screening for hepatitis B and C were performed respectively in 96% and 94% of our Tunisian patients before receiving any bDMARDs. This should be systematic to avoid HBV reactivation which can lead to fulminant hepatic failure with a severe prognosis.Disclosure of Interests:None declared