Background:Involving patients affected with rheumatoid arthritis or ankylosing spondylitis in clinical trials may be highly challenging: in a worldwide context of competitive rheumatoid arthritis and ankylosing spondylitis clinical research, patient engagement is key to optimize medical research and increase participation rates.Objectives:The aim of this study was to identify patients’ motivations for and hindrances to joining a trail in order to increase participation rate by implementing tailored services and information.Methods:An online questionnaire was submitted from August 2017 to October 2017 to Carenity’s French members affected with rheumatoid arthritis or ankylosing spondylitis.Results:136 patients affected with rheumatoid arthritis (n = 55, 40%, mean age = 55 y/o, 71% of women) or ankylosing spondylitis (n = 81, 60%, mean age = 48 y/o, 80% of women) participated in the study. 10 patients (7%) already participated in a clinical trial.Non-participants (n=126) exposed the incentives that may increase participation rate: reimbursing the expenses related to the clinical trial can improve their motivation (median weight on motivation to join a trial = 10/10) as well as a better medical follow-up (8.0/10) or leveraging the trial’s investigator notoriety (8.0/10). Patients’ healthcare practitioners could be leveraged as well: their favorable opinion turns patients on to clinical trials (7.0/10). On the contrary, a doctor’s negative opinion may strongly deter patients from joining a trial (median weight on reluctance to join a trial = 8.0/10). Communication should aim at reassuring them about side effects (9.0/10), potential risks for their health (8.0/10) and more generally the risk that the new treatment would not be better than their current one (8.0/10). Logistic challenges should also be taken into account: the trip between patients’ home and the site of the clinical trial is perceived as an important burden (8.0/10).Implementing tailored services and information would be an efficient way to reassure patients and increase their willingness to participate. 81% of non-participants would be enticed to participate if they had access to a website to exchange with healthcare professionals or to follow the results of the trial. 79% would be interested in participants’ testimonials and 74% in a 24-hour phone helpline. Spreading and clarifying information before the trial is also critical: 6/10 patients who participated in a clinical trial did not understand clearly if they will have out-of-pocket costs and 5/10 patients were also unclear on the terms and conditions for leaving the clinical trial.Informing patients via convenient channels is key: 88% of participants and non-participants think that an online patient community is a relevant medium to convey information about clinical trials and 81% of non-participants would like to have access to an information brochure about the trial process.Conclusion:This real-world study allowed to identify concrete levers to reassure patients affected with rheumatoid arthritis ...