ORIGINAL ARTICLE The frequency of infections in patients with juvenile idiopathic arthritis on biologic agents: 1-year prospective study Deniz Aygun 1 & Sezgin Sahin 2 & Amra Adrovic 2 & Kenan Barut 2 & Haluk Cokugras 1 & Yıldız Camcıoglu 1 & Ozgur Kasapcopur 2 Received: 1 August 2018 /Revised: 2 November 2018 /Accepted: 12 November 2018 # International League of Associations for Rheumatology (ILAR) 2018 Abstract Introduction The most effective and concurrently the safest treatment regimen selection is important to provide early control of juvenile idiopathic arthritis (JIA) and to have an acceptable quality of life. The effectivity of biologic agents as well as standard disease-modifying drugs is well documented in treatment of JIA. In spite of their high benefit, these drugs have the risk of serious infections. Herein, we conducted a prospective study to investigate the infectious complications of biologic agents in patients diagnosed with JIA. Methods Patients on biologic treatment regimen were examined by the pediatric infectious disease specialist in every 2 months during 1-year long. Results Throughout the study period, 57% (n:175) of the patients developed infection and 43% (n:132) of them completed this period without any infection. Upper respiratory tract infections which were treated in outpatient clinic were the most common infection. Only three serious infections (two pneumonia, one pleural effusion), which required hospitalization, developed. The infection rate was highest in systemic JIA and lowest in enthesitis-related arthritis (p < 0.001). The total rate of infection development after 1-year period was lowest for etanercept; it was highest for the patients on infliximab treatment (p < 0.001). Conclusion We comment that the altered immune system of JIA can be responsible from the serious infections irrespective of immunosuppressive therapy. Biologic agents can be safely used in JIA evaluating the loss and benefit statement. Keywords Biologic agents . Etanercept . Infection . Juvenile idiopathic arthritis Introduction Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease of childhood having significant physi- cal disability with high morbidity and mortality. JIA is a clinically heterogeneous condition with seven categories that have different characteristics and outcomes, which are based on the number of joints affected during the first 6 months of disease and extra-articular involvement. The cause of JIA still remains unclear, but the autoim- mune and autoinflammatory processes are held to be responsible. Dysregulation in cytokines that mediate in- nate immune responses is also a strong evidence [1–5]. Selection of the most effective and concurrently the safest treatment regimen is important to provide early disease control and to have an acceptable quality of life and to decrease the systemic complications of the disease [6]. The biologic agents as well as standard disease-modifying anti-rheumatic drugs (DMARDs) are highly effective thera- peutic choices in JIA. In spite of their high benefits, biologic agents have the risk of serious bacterial and viral infections as they act as immunosuppressant and immunomodulator thor- ough cytokine pathways. There are a number of studies eval- uating reliability of biologic agents, with various results and counter-view [7–12]. Currently, the association between the increased rate of infection and biologic agent treatment is un- clear due to scarcity of clinical and observational data regard- ing the infectious complications of biologic agents particularly in children with JIA. Besides, there is not also any report yet in our country. In this study, we conducted a prospective study to * Ozgur Kasapcopur ozgurkasapcopur@hotmail.com 1 Department of Pediatric Infectious Disease, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey 2 Department of Pediatric Rheumatology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey Clinical Rheumatology https://doi.org/10.1007/s10067-018-4367-9